Welcometothe
Space
TOUR OF THE
UNIVERSE Once upon a time. a man named Neil Armstrong stepped onto the surface of the Moon claiming it to be ·One small step for man, one giant leap for mankind." Join us as we take you
further than ever imagined across our Solar System and into deep space. Explore the Milky Way from Earth's natural satellite, the Moon. to learning all about the star at the centre of our Solar System. Further your understanding of how the human race is exploring the universe, as we search for life and prepare to become tourists in space. Learn about the science of space with the formation of the planets and the Space Junk Crisis. Finally, you will head into the deepest
depths of the universe touring alien worlds and uncovering the power of supernovas. In this book. you will also discover some of the wonders of the universe. and what mysteries they hold. Jump on board. and get ready to tour the universe.
space TOUR OF THE
UNIVERSE Ai; _ _ IrnoIIno ""*'IisI1inIlt
-
3 3 _ ....
Do
(Oll202~200
W_o: TwItlor: ........ IrNor;.... _ _~.
o
r..
. . ron_ ---
-= -...faceIlooO.-«
..... EdIt..
~~ _Atl£dll.. ,~-
....'
-_. -~
KaIloMapoos
w_~.
2tl--,. _. W;.......... wes'ld_•. WV13 lX! --~
.......,._.<0,"".bI'
010"-011110''''' ."..... ~ Lt~.........
~K &
Eire
Ttl 01202 S8e2OO
Dlo'_odln .....,,_ bI'
Go
~
c.otre, 18 ~ _ . Foo-' ""'ost,
NSW 2OB6. '01.6129972 8800
--
II.- RNt 01 _!or
The pef <:anrMlI """"pi
",~!
tho W_ "
Stfe<'\. London. SE1 OSU
~
_
_or .... _
thO _
.. n _ _
n the
LoItnls_....,. -'01""' _ _......""1"..'''....
kil«l matetioIlost
_t .... l<>.I_..,lis\l>t_ic"IoI .......... """..... Ltll.~.....
be _<>*lin
used ","""",.-rIO'"", WPOM'oIcri1l<;i$m..-.l _ . "'tho\.I(l1 tho _ _ "".
_to..- .. _ I s wtO
01~
.... ...- "poc. TOIl'
Jlf'us_ ...-.,......,.""""...
_ w i t h " " ' ~ _here..
oIl1lo ~ 02010lmaiint
PuOIiSIW\I ltd
ISllN 978-1909758971
Part of the
Space bookazine series
I.AG' • • PUILISHIN(j
the
on ers
• of the
From exploring our Solar System to the mysteries of deep space, find out what makes our universe so amazing 9
Discover the wonders of the Universe
Like reguLn Tl1iItler, 3D models like this Hubble survey pJedIct that dalk mailer is distributed unevenly throughout the universe The chilling discovery came to light in the Nineties
when astronomers realised the universe's expansion was accelerating instead of slowing, as they'd predicted. So little is currently known about the mystery. the tenn
'dark matter effectively exists dS a placeholder - a means to explain an unfathomable problem in a barely more
comprehensible way. Thanks to more recent discoveries we do at least have a rough idea of where dark matter resides.
Finding dark matter • Dark matter mapping The Hubble Telf:'S(opl:' helpl:'d create a 3D map that provides the fir5t dire<;t look at the large·scale distribution of dark matter in the universe
The globular image above depicts the distribution of dark matter across the universe. The COSMOS survey, a Hubble project studying the relationship between large scale
structure (LSS) in the universe and dark mattel. as well as the formation of galaxies - hdS offered the most compelhng l'VidellCl' yellhat known matter tends to cohabit the same space as the densest concentrations of dark matter. lust don't ask anyone what it is.., .
Gravity
cannot be
explained Gravity is a mind-boggling conundrum Despite being able to predict its effect with enough scientific accuracy to chart the locations of celestial bodies millions of years into the future, we haven't yet entirely grasped what makes it work. We know that gravity operates at the speed of light and attracts clumps of matter with a lorce directly proportional to their mass and is unlike the other three forces of nature, because it has a fundamental relationship With tIme and space, What we don't know is what particles are actually responsible lor creating the force of gravity, Researchers at particle accelerators on (,;arth like the Large Hadron Collider near Geneva, Switzerland are hoping to find the answer soon,
Discover the wonders of the Universe
Mining asteroids James Cameron and Google's Eric Schmidt and Larry Page establish the first asteroid-mining company
It might sound and look like somethmg OUt of a seW film, but asteroid mining Is very much a reallly, and one that could
Who's
greatly ~nefit humanity_ for dec.-.d($ it has been nothing but a pipe dream and. until recently, nobody had been able to devise a clear plan for long·term minmg of an asteroid
Tholl all changed whc!n a new company called Planetary RE'SOUfCeS. Inc outlined a clear goal In eally 2012 to mme near-Earth asteroids for valuable minerals 5eI up by some familiar and rich names. mcludll\8 James Cameron and Goog1e's Eric Schmidt and Larry rage. the company aims to supplement the E.1rth's nalural resources by developing and depIaying robol:ic asterold·mlning vehicles, RJghI now. Planet.lry Resources IS still in lIS very early planning stages. oIltempung to ldenllly lhe key teehnoklgies mal will allow lito produce the necessary machmery 10 forge tl1ese large minlng droids. However,lhe ulumate aim - and
one In whKh its b.x:kefs readIly accept is $lIn a number at decades iWiay - is 10 survey numerous asteroids for their mmefil] and water COOlent. before disp':llehing aulomated
"The aim is to survey asteroids for mineral and water content before dispatching" automated mmers 12
~
,---w Eric Schmidt Schmidl is lhe exerullve ch.airman of Google. He Is i1lso a celebrilted 50ftwilre engineer. mmers 10 harvesl them. Up 10 five Ofbuallelescopes are eXpecled (() be launched by 2014 10 begin lhe survey. Indeed. lhe exIStence of A.nelary Resourc:rs is fasemaung because il is ltl il fOf lhe long haul. creating a oomplel:e1y conceIVable roodmap 10 assel extr.JCIlOfl. If successtullhe endeavour could prove very profilable Iof the company, wnh suxlJes IndICating lhal mosl: a5111'fOOs are nch in mlllll'rais such.as iron. niclceland Ulanium • which are in resr.riellve SUPIXY on Earth. II these eiemenlS could be eXtracted and iAoc ed il would proYl" invaWble for fulure IndUSIry. Whal ts mosIfasanatll18- though. is lhalln ils mlSSlOfl (() mine asll'fOids. A.net.uy Resourc:rs could
, larry Page Piige is the CEO of Google and also its co-founder. He sped.alises in
computer sdence.
James Cameron Director 01
~
and Tenni"1aror 2. C.arTM!fOfl 41Iso helped buildthe~
Ch.allencet·
Peter Diamandis ~ndl5isa
............ .., ~e-llisht
expertin~
spICe
vehides.
Firing
lasers on Mars
The Science Laboratory mission to land the Curiosity rover on Mars blasted off on 26 November 2011 and is a simply phenomenal project Once 11 has parachuted down to Mars, the state-of-the-art vehicle has only one purpose - to help assess the habitdbilily of the Red Planet It will do this by performing various tests in its onboard laboratory. including large-scale chemical analysis of its rocky surface. using a ChemCarn laser to '1apoUlise pieces of the terrain for more effective study. •
Book a ftightto the ISS
Sp.JCeX·s Dragon sp3Cl'Craft is
exciting for all the fight reasons. As discussed earlier (see pilge 12) it has already begun cargo missions 10 the International Space Station. and in the next fl'W YCdrs it is set to begin manned expeditions to sp;!ce, the first private sp
to do so, It hilS already received funding from NASA under the COmmercial Crew Development programme. and by lOIS olt the earhest it is expected to stolrt ferrying up to seven astron
First visit to Pluto
Currently en roote to the dwarf planet Pluto, NASA's New Horizons spacecralt holds the record for the highest-velocity ejection speed from Earth's atmosphere of any human·made object. It was fired directly into an E,;arth·and-solar escape trajectory with the equivalent speed of S8,536 kilometres per hour (36.373 miles per hour)! Upon re
13
Titan's Earth-lil
occunence.lndetod. its surface ~n has simiLilr fe.uures, 100. such..s und dunes. riYerS,1akes and sus - ahhough the lauer's Woller' is most likely liquid metha~ and ethane. As such. il Is thought by scientists 10 poIentially be a habit.ll in which microbial extulenestriallife could survtve. or 011 the very 1N5l, act as a rich pl'ebiotk environment for their future cre.lIion. •
Discover the wonders of the Universe
Discovering new Earths Scientists are busy in their search for new, Earth-like planets outside of our Solar System and new advances in technology may help us find one soon Planet hunting is a new and exciting area 01 astronomy barely two decades old that, thanks to missions such as NASA:s Kepler telescope. is revealing more ,lnd more data about intriguing
detailed imagery of direct exoplanet observations, projects like NASA's James Webb Space Telescope and the European Extremely Large
new worlds outside of OUT Solar
exoplanets into view and {'\I('n study
System, known as extrasolar planets or exoplanets. Only in the Mst 20 years has suffident technology been
the composinon of their atmospheres.
available to allow us to categorically prove the existence of these planets. While we're still some way of! seeing
40-metre mirror . - Not only wilt the E-ELT's 40m (131ft) mirror take pictures of larger known ex1fasolar planets, it's also hoped il will observe Earth-sized exoplanets, 100
Telescope (I-.:-ELT) will bring Earth-size
The number of bizarre and familiar new worlds just waiting to be discovered is staggering. if estimates prove to be accurate. In our Milky Way alone there could be hundreds
of billions of planets, and so far we've found just a lew thousand. The ullJmate goal for planet hunting is to filld an Earth-analogous planet that could help ascertain whether hIe could
potentially grab a foothold outside of our Solar System. The key to discovering an Earth· like plalll't is to find those that are within the habitable or 'Goldtlocks' zone of a star, the area within which the conditions are thought to be 'just right" for water to form. l(epler-22b was the first such planet to be foulld and, while it is now thought to have a thick atm05phere that may be mhospitable to life, it was very influential in helping to spur the discovery of new Earth-like planets. One example of these was Gliese 581 g. a planet no mOle than
"Projects like the James Webb Telescope will bring Earthsized exoplanets into view"
Discover the wonders of the Universe four I.Jmes the mass of Earth silting right in the middle 01 the habitable zone of its host red dwarf star. While a year on this plalll't is only 37 days. observations suggest that GHese 581 g may be a suitable planet on which life could reside_ Another potentially life-harbouring planet is tiD 85512 b, a so-called 'Super-Earth', like Gliese 581 g. with a mass at least 3.6 times that of our home planet but with a temperature that could potenl.Jally allow for the existence of liquid water, which is thought to be one of the key components for HIe to form or survive. Over the next few years, as our methods of finding and characterising exoplanets become more allCl more sophisticated, irs likely that more Earth-like planets like these will be discovered all over the Milky Way.•
3 amazing Earth-like planets
" :"';
m .. massoftheEanh radius of the Earth
I·
,
Ii~ \...;;.~~,~.
"~
-
-
",,"
~-<.,..; ~~
•
:t~,;,.,
...
~,
C"ese581g DIIUnce 19Iw: if'1"" from brth: 20
Stu: (""Ioe"e SIll Constf:~n: lb. DI!Icovf!red: XlIO Mua:37mbdl.... l3r Tf:lllperature: .20"(
1ID85512b
DlsWKf: from £uth' 36lsh!,.,... Stu: liD 85512 ConstelLation, ""'" DI!Icovf!red: Xlll Mus: 3 lim bdlus: lXlIo:n
Kepler-22b
DlsWlCf: rrom brth: 620 iBhI)@ills StM: ~~22 Constf:l1lltlon:(~
........... """
MDs, IFl
10 fascinating
space facts you need to l
event could see the star reach a comparable brightness to that of a full moon.
TIle S~ce ShutUe Is _ more
NASA's youngest Space Shullie. Endeavour. having flown its last
mission in May 2011 is now on dIsplay
at the California Science Center in LA. There'.lI1Oft willer on Europ;l .... EMtb Data acquired by NASA's Galileo
spacecraft suggests there is up to three times morl.' water under the surface of Saturn'S moon "urapa than on Earth.
The clgnce of extRlenutlUl We Is 100 per ceDt ThaI's accordmg to the Drake equation,
a mathematical equation used to estimate the number of extraterrestrial civilisations in our Milky Way galaxy. Mr Drake's own estimate came to over 10,000 alien civilisations.
Vtrpn Gmct1c set to bke tourbb mto Ip;aee From late 2012 Spaceport America
began hosting the first-evcrspace
tourism fllghlS court<'Sy of Vilgin Galactic. It has 400 accepted rescrvalions already on the books.
A I4ap un', wortb o( ~ neulroa 'lou would -Icb More tUa the MoonllM1( Aneutron staris formed when a star 01 between eight and ten solar masses dies. Ateaspoon of it would weigh more than everyone on Earth. while d soup can would weigh morethan the Moon. World', blUftlldncope uny HI (Of completion In 2012 the Alacama Large Mill!mcter{ sub-millimeter Array (ALMA) m Chile was complete
movin.
Humans are:.oln& to Marl
NASA olnd Lockheed Martin hope to send humans to Mars by 2035 with the jointly created Orion spacecraft. TIN: S_lose, a billion ldlop;lDll everyHCoad The sun burns through a billion kilograms of its own mass each second. Tholt works out olt olbout three Empire State Buildings every second!.
Explore the Galaxies At the inner limit of the spiJal arms, the b.lr and hub are surrounded by a structure known as the
5·kHoparsec Ring (one Idloparsec is around 1260 light years). Although we cannot see it in visible light.
the ring seems to contain huge concentrations of starforming nebulas and young stars, it's probably the mam generator of new stars in the Milky Way. Above and below the main disc lies a relatively empty regIon known as the halo. Many faint,
long-lived stars pass through this region on tilted orbits, but the h.1la's most obvious occupants are
globular clusters - dense balls containing many tens of thousands of old, red and yellow stars that are generally found above and below the galactic hub. Similar led and yellow SldfS dominate the hub and
bar - they are relatively poor in heavy elements. which allows them to shine for billions of years
without evolving significdntly. As J result they are
known as 'Population J]' stars, in contrast to the younger, fastel·evolving and heavy·element·enriched 'Population [' stars in the galactic disc. Among aU these stars, the huge maJOrity are Jaw. mass red and orange dwarfs - stars with a fraclion of the mass of the Sun, which shine so faintly that they Cdn only be seen when they are relatively nearby, Brighter and more massive stars are much larel, but tend to shine out over huge distances and so appear mOIl' plOminemly in our skies. SimiLlrly, ageing but brilliant red and orange giants are common among the naked·<'YC stats seen from Earth, but in fact fal rarer than they might appear at first glance. What's more, stats In our galaxy seem to be gregarious - although they gradually drift apart from the open clusters in which they form, many stars
"The Milley Way is a major component of the Local Group - a small galaxy cluster some 10 million light years across"
26
remain together in binary 01 multiple stal systems. Recent research also suggests thai planetary systems all' also common· there may be at least as many planets as there are stars m the sky. Within the hub, statS become mor{" densely packed towards the centre of the Milky Way· the galactic core. Only X·rays. radio waves and some infrared waves can pass through these dense star clouds unaffected, but Ihey leveal an intriguing picture of the strange and violent conditions in the core Itself, Al radio wavelengths. the core is marked by a complex radIO SOUI«' known as 5.lgittarius A it consists 01 a bubble·like structure (SagittariUS A West) a few 1l'ns of light years across - probably the remnant 01 an enormous supernova explosion. Embedded within this is a three·armed spiral called Sagittarius A East roughly ten light years across. The middle of the spiral coincide-s with the densest concentration of stars In the Milky Way, and a third, point·like sourer of radio waves known as Sagittarius A' that is believed to mark the Milky Way's cemre. X'Tay emissions reveal huge bubbles and twisted lobes of superhol gas across Ihe region' a mix 01 supernova rt'mnants and the effects of hot stellar
Explore the Galaxies
The 1969 Lunar lander
Ascent stage This 2.8m (9.2ft) high and 4.0m x 4.3m (13.2ft x 14.lft) wide, Irreguiilr·shaped stage is mounted on top of the descent stage. It carr;es the astronauts to and from the surface of the Moon
lDsidethe Apollo lander
Antenna
Fuel tanks
The parabolic S·biInd steerable antenna provides a voice and data communications link with the Manned Space Flight Network. The parabolic rendezvous radar antenna is used when docking with the Apollo Command Module
An oxidiser (nitrogen tetroxide) lank and fuel (aerozine SO) tank power the ascent engine
Reaction control thl\JSter assembly Four cll.lSters of thrusters C
Crew compartment The pressurised compartment h
Descent stage
Ascent engine
The lower stage of the spacecraft has an octagonal prism shape, 3.9m (12.8ft) across and 2.6m (8.6ft) tall
Produces 3,SOOIb (16kN) of lixed thrust to launch the ascent stage olf the descent stage, and enables it to rendezvous with the Apollo Command Module
Storage compartments Egress platform
A quadrant of compartments contain lunar surface experiments, spare batteries and equipment. On the Apollo 15, 16 and 17 missions, the Quadrant 1bay carried the lunar Roving Vehicle
This allow<; the astronauts to crawl out of the ascent module ~fore descending the ladder attached to one of the landing legs
landing legs The four legs have large landing pads, and hokl the lunar Module 15m (4.9ft) above the lunar surface
Fuel tanks Two fuel (aerozine 50) tanks and two oxidiser (nrtrogen tetroxide) tanks power the descent engine
Descent engine Can be gimballed, and throttled between 10,1251b (4S.04kN) and 1,0501b (4.7kN) of thrust to enable the craft to descend from lunar orbit. hover and land on the lunar surface
Explore the Galaxies programme on ice. In 2003, just days after finalising a plan to bring CNN reporter Miles O'Brien to the International Space Station (ISS). the Columbia disaster brought the programme to a stop again. The era of true space tourism began in 2001, when multimillionaire entrepreneur Dennis Tito, a former NASA engineer. became the first private cilJzen to pay his own wayan a spaceflight. The American space tourism company Space Adventures bro~ered the deal wllh the Russian government to the reponed tune of $20 million (£12.7 million). Against NASA's wishes, Tito flew with two cosmonauts aboard a Soyuz rocket for a seven·day vISit to the ISS.
On his safe return, Space AdventUll'S got busy lining
up more would·be astronauts. It has since arranged ISS visits for six more ddventurers, mcluding billionaire Cirque du Solei! CEO Guy Laliberte, who
flew in 2009. While Russia was happy to sell an extra Soyuz seat when it had one available. it wasn't looking to make space tourism its primary business, All signs indicated the future of space tourism would be privately owned spacecraft. The private spacecraft era began with the Ansari X Prize, a $10 million (£6.3 million) reward for the first private team who built a 'ship thai could carry three
people to space twice in three wreks. Inspired by the early 20th Century prizes for aviation advances, the X Prize Foundation issued the challenge to move lhe world towards low-cost sparenight. The plan worked_ Backed by funding from Microsoft co-founder Paul Allen, a team led by aerospace engineer Bun Rutan completed !he challenge on 4 October 2004, The winning vessel SpaccShipOne, employed a number of Innovations to minimise the danger and cost of launch and re-enlry, Most notably, instead of launching !he 'craft vertically from the ground, the team built a jet-powered mothership to carry SpaceShipOne into high altitude,
Space tourism Rek>ased at about 15 kilometres (nine miles). the 'ship needed much less rocket IXIwer to reach space. The X Prize Foundation set the bar at the Karm.1n line, the conventional 'edge of space', While there's no real specific borderline, an altitude of 100 kilometres (62 miles) puts you slightly above the point where the atmosphere is too thin for aeroplanes to generate enough lift to fly. As difficult as It is to reach this region of space, known as suborblt. it's far simpler than climbing into orbit. The added thrust alld fuel requirements make it much more challenging. [t's no surprise then that most burgeoning space tourism companies are fonowlng SpaceShipOne's lead
alld setting their sights on suborbital trips. Billionaire entrepreneur Richard Branson was so impressed with SpaceShipOne that he parmered with Burt Rutan to make the concept the backbone of a new commercial spaceflight company: Virgin Galactic. Branson foullded the company in 2004 and predicted his first customers would fly in 2007. He pushed back the timeline, when he and Rutan opted to create a larger version of the spacecraft alld its mothership. dubbed SpaceShipTwo and WhiteKnightTwo respectively. After training exercises with the first 100 customers, Virgin Galactic has deemed the two-hour
trek safe for an adults in good health. The company expects to begin commerdal flights by 2014. at $200.000 (£127.000) a seat. It has already taken $70 million (£44.4 million) in delXlsits, from more than 536 astrollilut hopefuls. Branson offered William Shatner a free ride on the inaugural flight. but he declined. citing an aversion to vomiting and fiery crashes. Branson has, however, mallilgcd to sign up Tom Hanks. Brad Pitt. Angelina Jolle alld Katy Perry. The American company XCOR Aerospace is developing a promising commercial space plane as well. Its design. the Lynx, forgoes the mothership strategy. opting instead for a rocket-powered
Explore the Galaxies has been charging, While Sp.1ceX is currently focused on serving government and fC'scarch clients, its vehicles may be the future of commercial spdC(" travel. The designs cxcro:! NASA safety standards, With mnovative features such as a launch pad release system thal keeps the vehkJes grounded until all first-stag<" engines are workIng correctly. NASA also awarded Sierra Nevada Corporation $21.2.5 millton (EllS million) to continue work on the Dreilm Chaser, a vertical-takeoff. horiWnlal-ianding spa<:eC"liIf1 resembling iI scaled-bilck Space Shuttle. The spacecraft will serve as a backup in case the larger Boelns .lnd SpaceX projects don't work out. The Shutt.le-Iike Spill'e plane approach could prove a great fit for commercial flights to orbit.
horizontal takeoff. Wllhin a mmute of starting the rockets. the Lynx will reach supersonic speeds. before
wring up for a 7S-degree shot to subOlbit. XCOR is designing 1m.> 'ship for cargo and spact'
tourism missions, wIth space for one pilot, one pass("nger and multiple payload areas The nonprofit
group Citizens in Space has already reserved 100m 101 both payload and passengers on len Lynx flights. Its plan is to lake 100 or so cil.Jzl'n·sc!ence experiments Into suborbit in
Astrium annoullCt"d its own space plane project In 2007. Its CO~1 indudt'S the unique combination of jet
engines and rocket motors on a single spacecraft.
During takeoff. initial climb and landing. the 'craft would operate Ilk!' a conventional private jet. At high
altitude, rockets would propel It through the upper atmosphere to suborbit Astrium initially announced pla.ns to begin flights in 2012, but the ecOl1Omk downturn led to the project being put on hold. While the immediate focus of space tourism is reaching suborbit, trips U1IO orbit may not be far behInd. Several plivate companies are working on vertical·takeoff spacecraft to bring p.lssengers to space stations and beyond, When NASA shut down the Shuttle programme. it lost its means of g<'ttlng astronauts to the [55. opening lhe door for private firms to liIltlle void. [n August 2012. NASA awarded contracts to thret' comp.lnies to develop manned sp,u'Cfalt to replace the Shuttle programme wlthm the next five y<-aTS, Boemg received $460 million ([290 mil1ion~ but relative newcomer Sp.Kt'X wasn't far behind, wlth S440 million ([280 million), Founded In 2002 by Elon Musk (of PayPal fame), the company has already seen greal success with its Falcon launch vehICles and Dragon spacecraft. In May. SpaceX becolme the first private company to bring Colrgo to the ISS, SpaccX expects to launch Its first manned sp.1ceflight in lOiS. Musk s.:tys l! WIll be olble to bring seven J5!Tonauts to the ISS at a ume, at a cost of $.20 million (£1.2.7 million) pcr seat a roTlSlderable discount over the $63 million (£40 million) Russia
"SpaceX's Elon Musk has vowed to mount a manned expedition to the Red Planet in the next 10-20 years" When routine orbital flights are finally feJsible, tourists wnl nro:! somewhere to go. The ISS is the prime destination today. but it can only hold six people, and those spots are typIcally reserved for reseilrl:hers on offjcial business, Bigelow Aerospace hopes to add many more station options. After the successful launch of its orbillng sp.lCe habirat modules. Genesis I ilnd II, it's developing a production version Qlled the RA 330. Nilmed for its 330 cubiC metres (11.650 cubic feet) of useable space, the BA 330 is an expandable stallon that inflates once in orbit. Each BA 330 will be able to support six visitors at a tlme. or clients can l"Onnect multiple units to create a la.rger station Aecause lounder Robert Bigelow owns the hotel Chain Budget Suites of America, reporters often
assume the new stations will be 'space hotels'. But for the immediate future, the company is catering to government and corporate chents lookmg for microgravity research spilre. Another tourist optton Imght be a tnp around the Moon_ Spac:l' Adventures says it's already designed a 17-dily tnp to the far side ilnd bilck. In May 2011, it reported tha.t one pilssenger had alreildy signed up for the $150 million ([95 milhon) tour, and thilt. it hoped to begIn trips as early as 2015. US company (,:xcaltbur Almaz, bilsed on the [sle of Man, Is offering lunar trips on board refurbished Soviet-era spilcccrilit. Tickets will cost around $158 million (£100 mi1lion~ and it hopes to begin flights in 2015. Beyond the Moon the next logical destination is Mars.SpaceX"s Elon Musk hilS vowed to mount a manned expedition to the Red Planet in lhe IlI'Xt 10-20 years, with 01 Without NASA's help. While some experts estimate a Mars mission would cost $5 to $30 billion (£3 to £19 billion), Musk believ('s SpilceX can get the ticket price down to $500,000 (£317.000) within ten years 01 the first tlip. Throughout the commercial space exploration industry, people share Musk's vision: that PJivate companies will have the motivation and me.,ms to advance space exploration laster than government programmes, This is the reoll promlSI' of Sp.K(' tourism. And with so much recent progress, there's fC'ason to be optimistic about tcchnological advancemenls. The buslfless model shows promise, too. A 2012 study funded by the US Federal Avl.allon Administlation and Space Florida predicted that the space tourism industry could g<'nerate $600 million (£380 millton) In liS first decade_ Of course, we've had that just-on-the-cusp feeling for a while now. In 1968, the airline Pan Am created a lunar reservation desk in antkip.1tion of a new Sp.1Cl' diVISIOn. More than 100,000 people reserved a spot. and the airline sent them an a numbered 'first Moon Flight' card, The tlekets arc worth a lot to collectors, but they won't get you on a lunar cruise Pan Am's been OUI of huSIllCSS lor over lO years, With any luck todais astronauts in waiting will fare better..
Tourist destination What tourists can expect from their trip to space
• :v
38
• •
Space station
Transportation
Incredible views
Crew
Excalibur Alman spilCC station, based on Soviet Almaz designs, would enable paying tourists to live al'ld operate in space for extended periods
This transport capsule would take the ailronauts to the space station and. at the end of their mission, it would bring them back
Alarge wil'ldow at the bottom of this section would prO'llde incredible views of Earth for the residents on the space station
Three crewmembers will be able to live lor periods on the station, performing both scientific al'ld recreational activities
Space tourism
"There are ten billionaires now investing in private space tourism companies" John Spencer, founder and president of the Space Tourism Society Why did you decide 10 get involved in space tourism in the first place? [always Joved science. space and
and In 1978, ll'Nlised J couJd be a space architect - one of the first In 1982, Irealised that the way to sdmulate
1=
Spencer created the first interior designs for NASA's SpaceHab Module
••
space exploration and development was to create d spaa' tourism indusuy so ITlOfl' and more people wouk:! have a chance to go - to have that life-ehanging space experience. So I JUst started it Never looked back.
What are the main advantages or commercial space expIoratiOD over government space programmes? Actually. wa-king together like we are doing now with NASA paying SpaceX to supply CaTlP to the ISS is d great thing. The map- advantage for !Xivate space enterplise! tourism companies lSthat they ~ profit motivated so very eUkient. and [here is no limit to how large they can grow. The space industry is totally SCillable and had limitless potential for bolh profit and prestige. What's the biggest misconception about space tourism? That it's in the future, On 28 April 2011. our Space Tourism Sodery (S'1'S) hosted a dinner in LA ce1ebrating the ten'year anniver.>ary of the liftoff into Earth orbit of
aspect aOOlt space traveVexperiefK.'e. By going out we
have a unique perspective inward.
Dennis Tiro, the work.!'s first private space travellet.lle
spent over a week on board the ISS. Since then. there have been seven other private space traveller flights to the ISS, with one person nying twice. There is a waiting list of people who can pay the $45 million (£28 million) for a night but there is no room Cf1the ISS any 1l'lClre.
What is the biul'st obstacle for space tourism at this moment in time? Passenger vehicles to orbit and places to stay. There is a waiting hst plus kltteres. and there wIll soon be suborbital flights. Ir"s not the Il1OI"lt'Y orthe regulations, it's just doing iL There are ten bUlionaJl'l'S now investing in and building private spaa:- enterprlSel 10unsm companies. What aspect of space tourism is most exciting to yourightnow? First, the fun designing realspact' tourisms!llps (yachts and cruise ships) and lunar resorts and spas, I Iovc desigmng forzerogravity.lt's what I cdll pioneering the design frontier. Second. the f.xt that going to space is a tl"U{' hle-changing CKpcrience, and a grl.'al one. Almosl ('V('ryorlC who has gone wants to go back and has d far gn>aWl appreciauon 01 how bedutilul our home work! IS and how we nrod to work more clasl.'fy together. This 'Overview' ('fft'dls in my opinion the most impondnt
or
What's next for space tourism? BJgl'low"s lIlflat.lble space habltdt with SpaceX providing space access to assemble it and then the people iPng to and from iL A really big deal will be Space Adventures COIlducting the first private lunar nyby mission with tWO prIVatesp
from Earth orbit could someciay become an Olympic sport, and my concept for 'Ille Great wnar RcM!r Race' Will be in the works. How about inlOOyears?
Beyond belief. Mars tourism will be in full swing. and private exploratIOn of the outer planets w1l1 be the new adventure for the rich and the bold. What advice do you have for anyone who is looking to work in space tourism? Move to LA. Or join the Sp
adventure tr.lvel groups and attend lTIE'l'tings. Just start!
What is the Space Tourism Society? Founded by lolln Spencer in 1995, the Space Tourism Society is the first Olganisation specifically focused OIl the space 10urism industry. Its goal is to open the possibiJny 01 space trd\ll!l up to as many people as possible by mtnxluctng the likes 01 the trd\ll!l and 10urism industry and the financial community 10 lhe idea of realistic space tourism.
41
Explore the Galaxies
TheArecibo message On 16 November 1974. astronomcrs Including Dr rrank Drake and Carl Sagan devised a message
10 send Into thl' distant leaches of space. The message was Intended to show the possibilitIeS of
communlc
•
•
1. Numbers
4. Double helix
The numbers ooe to ten
written in binary.
A graphic of the double heli~ structure of DNA.
2. DNA
5. Population
These represent the atomic numbers of the elements that make up DNA.
A figure of a human and Earth's population.
These are the formulas for the sugars and bases in DNA.
44
international endeavour to discover Signals from an alien race drifling through the cosmos, Next is the search for elCOplanets (worlds outside our Solar System), an area of research that has only gained credence in the last couple of decades. The field of planet hunting may be young, but it is already providing us with fascinating results that may soon help us find an exoplanet just like Earth. The final area of research is the search for microbial life. foss!lised or alive, on other worlds inside our Solar System. Until now this has largely focused on Mars. but places like !:.uropa and Titan could also prove fruitful to explore. The oldest of the three areas of research is Sltl'l, using antennas around the world to look for alien signals, In 1959. Giuseppe Cocroni and PhilJp Morrison, two physicists from Cornell University in the USA, suggested for the first time that it might be possible to communicate with another intelligent race among the stars using microwave radio. "The probability of success is difficult to estimate: they wrote m the journal Nature, "but if we never search, the chance of success is zero: At around the same time a young radio astronomer named frank Drake came to the same conclusion, and in the following year he used a 26·metre (85· foot) telescope in WeSl Virginia, USA, to conduct the first se
"We can't be the only instance of a race, we just can't be" SirPatrickM""",
•
3. Formula
Every month we ht'JI of incredible new exoplanets in planetary systems seemingly llkc our own. and we leam more in the search for past 01 present microbial life as missions like Curiosity gain worldwide attention, but for some reason lhe nOlion that we might be just one intelligent race among many is yet to receive much support from the public atlargc, Many people today still seem to have the same opinion that was prevalent In the mid to late 20th Century, that aliens are something that belong only to the realm 01 science ficlion, but this is In the facc of ovcrwhclmmg evk!cnCt' to the contrary, With every passing yea!, every new discovery of an exoplanet. every observation of frozen or liquid watcr on othcr bodies in the Solar System, it lX'Comes harder
6. Solar System Agraphic depkting the Solar System.
7. Dish Agraphic oflhe Arecibo dish and its dimensiofls.
1.
III
1
\
'JJ
•
~f 14 1 3
1 •
•I
huge amounts of power that would be easy to spot, but this was not $0. It was widely believed that 510.,.1 had a good chance of success, though, $0 in the Seventies NASA threw its hat into the ring. It established SETI programmes in California at its Ames Research Center in Mountam VlI!'W and the Jet Propulsion Laboratory!n Pasadena to look for signals around stars like our Sun or otherwise.!n the mid·NinetK'S, however,lunding was cut. and the srn Institute was forced to go it alone. srI'! uses a number of antennas and arrays around the world. such as the Allen Telescope Array in California, to observe distant stars and discern whether they are emitting any artificial signals produced by an intelligent race. Within minutes 01 observmg a star they have an answer, but to this day they have yet to find any conclusive evidence of extraterrestnaJ Intelligence. Undeterred, workers at
SETI continue to search for signs of life, and they're extremely confident that they will find something. To aid in SEn's study, the hunt for habitable exoplanets might allow us to find worlds where life could reasonably be thought to reside. Finding habitable exaplanets that Slo.i'l can study for signals is something that will prove of great importance. Of course, planet hunting itself is an area of astronomy that IS not even two decades old - the first exoplanet was not discovered unti11995, But while planet hunting might still be in its infancy, the results we have obtained from lust a handful of telescopes are astounding. NASA's Kepler space telescope, which launched from Cape Canaveral in March 2009, has found thousands of planet candidates in b.arely four years of operations, and some of these offer tantahsing hints of being habltabk>. But KcplC'r is lookIng at just a tiny portion of our gIant Milky Way, which m turn is r!'latively
~
1
~ 12 .12 31 1
3
1
n
1~1
'ld
1
1
I
1 1 I
small m th!' grand schem!' of the univC'rst'. Ba5l"d on data from Kepler, astronomC'rs at the Harvard· Smithsonian Center for Astrophysics t'Stimated m January 2013 that there were at least 17 billion Earth· sized ('xoplanets in the MIlky Way, That's not a typo; billion. not mtlll0n, Consider that there are about 100 billion galaXlCS in the known universe. and things start to 8<'1 really cXClllng. Is It really possible that. out of 1.7 trillion trillion pot('nllal planets in the 13.7 bl11ion·yt'Jr·oId universe only one, Earth, had the necessary conditions 10 produce Intelligent life? Many leadmg scientists bellcve thiS to be unlikely. Kepler, holvt'vcr, can only reveal very basic data about an exoplanet. includmg its size, mass and orbit. Future telescopes. like NASA's Jamt'S Webb Space Telescope, wln allow us to study these planets 1fl even more detJil TIns giam space observatory, whkh will launch in 2018, might be able to directly image exoplanets and ('V('n rcvealthe composltlon of
47
their atmosphere, a viLaI clue in discerning whether they are habitable or llOt. Groundbreaking research into the possibility of measuring the atmospheres of exoplanets for signs of methane, oxygen and other elements, or even looking for signs of artifKialllghts (just as we can see the Earth at night from space) will bring us closer to finding alien civilisations, While we're searching for alien life, however, could it be possible that other extraterrestrial races are also doing the same thing? We've been broadcasting our position, both intentionally and unintentionally, by emitting radio waves for about a century. If anyone is within 100 light years of Earth, they will be able to hear us. In fact. in 1974 we sent out something called the Arecibo message, a broadcast of radio waves that, for the first time, contained data about humanity that could be interpreted by an alien race and understood to be a call from our civilisation to theirs. It's not incol"ICeivable to think that other races might have done the same thing; maybe there are thousands of Arecibo messages streaming through the galaxy, but we just haven't come across one yet. With all this talk of exoplanets, habitable worlds and aliens, however, you might be forgiven for having one question burning in your mind; if there really is intelligent life out there, then where is everyone? You're not alone in thinking this, Way back in 1950, astrophysicist Enrico Fermi asked this very question, which became known as the Fermi paradox, He argued that because the galaxy Isn't teeming with spacecraft, or that we've never been sent a message from aliens, then either interstellar travel must be impossible (therefore dashing our hopes of ever exploring the galaxy) or we are the only Intelligent civilisation in the universe, There are a number 01 explanations as to why this is so, but the mOS1 plausible relates to the history of a planet IJke Earth, Our pl.alK't is 4,6 billion years old, but only in the last scvcral hundred million years has it been inhabited by sophistIcated organisms, Only in the last several thousand years has Intelligent and senllentlife, namely humans, made its mark on the globe, And only mtlle past one hundred years have we seriously begun observing and exploring the cosmos, and also sending out signals of our own. Humanity won't be around forever: an extinction event either natural or man·madc, could cut short
Have we already
found life?
There have been several instances where controversial evidence suggested that we may have already found life elsewhere in the umverse
Allan Hills 84001 In Antarctica on 17 oe«>mber 1984, a team of American scientists found a meteorite named Allan Hills 84001 (AtH 84001) that shot to fame 12 years later when it was announced that it might conLain microscopic fossils of Martian bacteria. However, no conclusive evidence could prove whether this was so,
The Viking probes In 1976. NASA landed two probes on Mars, Viking 1and 2, which had instruments to perform biological experiments on the surface, Controversy surrounded the results; early indications sugges1ed they'd found evidence of organic compounds. but some claimed that the nature of the e~periment, which heated soil samples, would have destroyed organics, wggesting the results were erroneous
49
our ambitions to continue exploring. That would
mean that an intelligent civilisation hdS only a brief period to make a mark In the liretlme of their planet
If we're going to find one, we're going to need to
continue our extensive search. as it may be that every habltable planet has only a comparatively bnef window in which Intelligent life thrives, J lowever,
.~J
Get involved withSETI [f you're
jnr~ested
in 1)e(oming an alien hunter,
then there's never been iI beller time to gel Involved With the SET] lnslitule_ Head over to the website at WWW.seti0l8tofindOl.ll mOle, You c
50
searching for intelligent extraterrestnal
life isn't the only hunt currently on the go. As mentioned earlier, our robotic exploration 01 the
Solar System is looking .lIthe possibility of microbial Ufe residing on the surface of Mars, or perhaps one of the pOtentially habitable moons such as Europa, Ganymede or Titan. From Landl'rs to orbiters to probE's, we've barely scratchl:'d tl\(> surface of the secrets some of thl' orher destinauons In our Solar System might be hiding, In the mid·Sl'venties, NASA conducted the first asuoblology l'xperiment outside of Earth. sending Its Viking I and 2 landers to Mars to dig into the soil and look for signs 01 past Of prt'Sent life on the Red Planet. 11K' results proved to be inconclusive but they Sp.lrked a hunger to learn moreo; light now. the Curiosity rover is makmg its way across thl'
Martian surface to answer the very SJme questJon. And even here on Earth, research is provmg usl'fuL We've found life in the deepest. darkest and coldest places, whethel iI's dt the bottom of d frozen lake or in highly (lCldk l'nvironment5. Research like this could help us to one day look fOl life on hozen worlds ilkI.' Europa or llqllld·ocanng pI..Kcs like Titan. In this feg.nd. dstrobiologists ale hopeful of one day discovering microbial life. Thereforl." in our continued hunt to prove that Earth is IUS! one world where ute has mack> a mark in the universe, It Will be down to the work of various people around the globe to make the vllal discoveries that could mdicate the presence of intelhgcnt 01 baSIC liJe elsewhere. Whether it"s experts at NASA working on a high·profile, next·generatton planet·hunting machme such as the JanlCS Webb Space Te1csrope, or it's the valiant workers who are lookmg fOlslgnals outside of our Solar System at SET!, or even the asuobJologists searching for bactefia on another world. these dedicated people Will continue to work towards findmg alien life. They
The Dragon space capsule The first commercially produced and operated spacecraft to successfully enter orbit and return to Earth, and the first to deliver supplies to the International Space Station Elan Musk, founder of SpaceK, named
this spacecraft
regarded this v~nlUre as \)(>mg as credible as a the mythical beast. The Dragon is a reusable cone-
shaped space capsule. It has a pressurised compartment to carry cargo, which in future can be refilled to carry seven crew members. An unpressurised servIce module beneath that section contains navigational equIpment and propellant for the Draco thrusters that enable the 'craft to be manoeuvred in (,;arth orbit. Underneath it is a PICA-X heat shield
that can Withstand fe·entry from £
arrays, and inside It contains additional cargo. A nose cone covers the 'craft when It is launched to protect it from the aerodynamic lorces created during lift-off. The nose cone IS jettisoned when the Dragon enters orbit. and the trunk is discarded shortly before re-entry and is not recoverable. At the moment the Dragon capsuk> uses parachutes to land in the Pacinc Ocean. and IS recovered to be reused for futun:> missions. 1lK'n:> an:> plans, however. to fit SupcrDraco thrusters and L:mdmg gears to the capsule to enable ilto 1.meI on solkl ground. After being founded in June 2002, SpaceX developed the two-stage
52
Falcon 1liqUld-luelled rocket It W.lS the first commercial project olns tylJ'C' to put a satellite into Earth orbu on 28 September 2008. In the meantime. SpaccX began work on the Dragon CJpsulc concept in 2004, A year later, NASA announced its intention to lund privJte companies to build spacecraft to resupply the International Space Slatlon (ISS). Under this Commercial Orbital Transportation 5<'rviccs (COTS) developmenl programme. SpaceX was Jwarded $278 million USD (fJ7S million) as 'seed money' to develop the Falcon 9 rockl:'t. In Oe1:embcr 2008. NASA selected the Falcon 9 and Dragon spacecraft combmation 10 lcsupply lhe ISS under J $1.6 billion (£[ billion) Commercial Resupply Services (CRSj contract, ThiS would pay lor 12 r<'Supply missions that will take at leasl 20,000 kilograms (44.000 pounds) of CJrgo_ Further lunding was promised for .lny Jddltional missions. AboilerplJte verskm of Dr.tgOn was launched at Cdpe Canaveral. Florida on 4 June 2010, This tested how well the Falcon 9 rocket performed and eVJluated the eflectiveness of the Dragon deslgn. Afler}()() orbits the capsule re-entered lhe F.arth·s Jtmosphere on 29 Junl:' 1010. The NASA COTS schedule CJIIed for the IJunl;h of thl:' first Dragon demonstration nighl to occur in IJle
2008. However_ development delays meJnt thdt it wJsn't launched until 8 December 2010, when a Dragon spa~rafl was senr into Earth orbit. Alter rwo orbits it successfully re-entenxl the E;anh's atmosphere and splashed down in Ihe PaCIfic OCean. In nself this was a historic ~ent. as it WJS lhe firsl time a commercial company. as opposed to a government space agency, had launched, orbited and recovered Its own sp,lCecraft. The next Dragon demonstration missiOn was planned to rendezvous with the space stJtion and the third missiOn would actually rendezvous and dock with the ISS. After some dlscussion. NASA gave Jpprovalto SpdteX to combine the two missions so that the next Dragon could dock WIth the ISS, Asenes of engin~nng tests and other delays meant that instead of launching in the summer of 20U or early lOll, it
module, NASA's commander Sunila Williams said that it "looks 1I~ ~'ve tamed the Dragon: The 'craft dehv('[ed crew supplies. vehicle hardware, eXlJ'C'riments and Jn ultra·cold freezer for sclentinc samples. It returned to Earth on 28 October 2012 with 7'>8 kilograms (1,700 pounds) of cargo Three further missiOns to resupply the ISS are plJnned and these wlll include usmg the trunk compartment of the DrJgon, llowever. other exciting plans include the development of J Launch Abort System and a lIlesupport system th,lt woukl enable SpaceX to Sl'nd manned missions Into orbn and to the ISS in 2015. For Jongl:'r missions the DrJgonRider would be abll:' 10 carry seven crew members and be capable of docking with the iSS lor 180 days or more, Jnd It could Jlso incorporate a launch escape systl:'m that can be used to IJnd It on the ground rather thJn splashing down in the ocean. Unmanned DragonLab flights ale also planned lor 1014 and lOIS that will be able to cJrry pressuriscd or unpressurised payloads into orbit. Jnd beyond the immedlatl:' horizon there are ambitIOUS plans to usc lhe Dragon (apsull:' as an unmanned Mars l.meIer ·cralt. The RedDragon would be capabk> of delivering 998 kilograms (2.100 pounds) of payload to the surfaC(' and could search for water and signs 01 MJrtian life.•
The Dragon space capsule
The International Space Station's Canaclarm2 robotic arm grabs lhe Dragon capsule and manoeuvres it to
dock wilh the station's Harmony module
Inside the capsule
Nose cone
Trunk
The nose cone protecls the capwle during launch and Is jettisoned Thrusters before entering Earth orbit Nitrogen tetroxide! monomethylhydrallne propellant provide<> 40kgf (90Ibf) of thrust to 18 thrusters, to carry out orbital manoeuvres
This unpressurised 14m] (490ft') volume
Solar array There are two articulated
Hatch
solar arrays, each with four solar panels
(omp~rtment
carries
i1ddition
(an ~ enlarged to a volume of 34m] (I,200ft')
Docks with the International
Space Station
Pressurised compartment This section hilS a volume of 10m) (353ft l) and Is pressurised to enable It to carry specialised payloads or up to seven aew members
using a Pas~ve
(ommon Berthing
Pressurised
Mechanism
compartment
(PCBM)
In cargo mode
this is fitted with
Heat shield
a modular fade system to carry standard-sired payloitds
Service module Contains computers, guidance navigation equipment, eight propellant tanks and two pressurant tanks
sensor bay The door of this unpressurlsed comp.lrtmeot opens after it enters orbit and closes before re-entry
Backed by 5paceX Proprietary Ablative Material (5PAM), this is the best heat shield currently available for space capsules
Falcon 9 rocket The Falcon 9 is a two-stage rockellhat was spedfKally developed to launch
the Dragon space capsule. It measures 59.2m (227ft) high and has a diameter of 3.6m (12Ft) and can carry payJoad.s of 1360-6,BOOkg (3,OOO-15,OOOlb). The first stage is IXlwert'd by nine Merlin Ie engines that produce a thrust of600,OOOkgf (l,320,OOOlbf)
atlift·off with a burn time of 170 seconds, while the shorler second stage Is powered by a single Merlin englill'. It has a bum time of 345 seconds and can be reignited lor two extra bums. The Merlm engines draw upon the legacy of the rocket engines produced for NASA's Apollo programme, and
incorpor.:Jle numerous safety features. AtlJunch, the rockel is held down when the first SlagI' is ignited and it is only released if everything is workmg correclly.1f lhere is J faultlhe engines are ShUI down and the locket IS drained of propellant. After launch il can successfully operale even if one of the first·stage Merlin engines fails.
53
Explore the Galaxies •
neater space training How astronauts are prepared for danger-filled space missions in NASi\s Neutral Buoyancy Lab Training rOt the weightlessness of space IS a major undertaking on NASA's part thaI requires a dedicated test facility and a ballery of cutling· edge equipment. As zero gravity freefal1 on a specially adapted night isn't practical for long training periods and anti·gravity 'machines' are set to remain the stuff of sciell(e fiction. NASA uses the 23.S·mlllion-Htre (6.2·million·galJon) giant swimming pool at its Neutral Buoyancy Lab in Ilouston. Texas. Neutral buoyancy itself is a property of an object that gives it an equal tendency to float to the surface as it does to sink to the bottom, so that it
appears to hover in the same place In
water. This projX'ny of neutral
buoyancy is very simIlar to the
weightlessness endowed by the lack of gravity in space: an astronaut wearing a neutral buoyancy suit in the pool is easily manipulated, just like they would be in spdCt'. but there are some key differences. The water drags on the astronaut to make movement and certain actions (like keeping an objo:t still) more difficult than it would be in space. while makmg it casicr to sct an obJCCI in motion. Thc other problem is that astronauts aren't truly wcJghtlc-ss
and can still feel the weight of their bodies while in the suit. For both these
reasons, performing any tasks slowly and an awareness of the NBL pool can help minimise these limitations. The 12,2'metre (40·foot) deep pool is primarily used for extra·vehicular activlly (EVA) training. Astronauts, particularly those embarking on a mission to the International Space Station, practice full spacewalks lasting five hours at a time, manipulating objects and moving around Large·scale mock-ups of the craft they will be working on. The fully completed ISS, at 107 x 73 metres (350 x 240 feet). wouldn"l fit inSide the NBLS 52 x 31 metre (202 x 102 feet) pool. but smaller replicas 01 the module the astronauts will work on are effeclJve enough to !fain With. The curren! standard for NASA IS that astronauts. depending on th(' difficulty of the EVA. spend fil/{' to seven times the amount 01 lime
training in the NBL as they would for the actual EVA The suits each astronaut wears for the NBL pool are very similar to those used on an E,:VA. Many of the suit components hal/{', in fact. been salvaged from spacesuits that have already seen some EVA action in orbit on the ISS. Ap.m from the addition of weights and neats to gIl/{' the suit with its wearer Inside the properly of being neutrally buoyant while in the water, NBL suits are distinguished by their life support and environmental control systems. These are self-contained with space EVA suits but while traming in the pool, they're provided by an umbilical cord attached to an external machme that supplies electricity, water coolant arK! pressurised breathing gas Naturally, safety and the health of the astronauts·in·training is carefUlly observed while in the pool. Although the dives aren't partICUlarly deep (12 metres!40 feet. while deep for a swimming pool is considered a shallow dive) they arc for long penods of time. So the NBL has a full complement of medical staff on hand consisting 01 two physiaans, two paramedics and 12 physiology personnel. The NBL also has a hyperbaric chamber on·sue to treat any dil/{'r suffering from decompresSion sic1mess . otherwise known as 'the bends'. •
Destination Mars It was forme Apollo astronaut and second man on the Moon Buzz Aldrin who uttered the words, 'Forget the Moon, let's head to Mars!" This is something that mankilld has been working to achieve since the Sixties. ~leets of flyby missions, orbiters, rovers and Llndes have been sent on one·way missions to shape our ullderstanding of the Red Planet. setting down the groulldwork that will one day lead to the moment an astronaut sets foot on Martian soil. At an average distance of around 225 million kilometres (140 million miles). Mars might IlOt be as close to the Earth as the Moon or Venus. but the ruddy·coloured pLanet's potential to provide us with information to sate our appetites for knowledge as well as the opportunity to expand our species to allOther world, today encourages generations of scientists to overcome this distance with reLative ease. However, It was not always this way. The Soviet Union was the rlrst country to launch robotic missions to Mars, with a number of failed launches and probes in the Sixties. By the Seventies, howeve, they had compelllion from the Americans. With two countries setting their sights on I.hl' Red Planet, the race was wen and truly on, but who would get there first? On 19 May 1971. the USSR's Mars 2 successfully raced through the last of Earth's atmosphere with the Red Planet In Its sights. Russia was In with a good chance 01 winning this round of the Spare Race. With the suCC't'SSful launch of Mars 3 laking place a mere nme days later. thiS only reaffirmed i.hl' Soviets' confidence. However, on 30 May 1971 NASA released Mariner 9 mto Till' skies above Cape Canaveral. hot on the heels of Mars 2 and Mars lIt reached Mars by 14 November of till' same year, beating I.hl'sluggish Mars 2 and 3 by a few weeks. Even so, Mariner 9 had to walt out months of relentless dust storms raging across Mars before it could take any of the 7,329 clear Images of rhe Red Planet that it uillmately beamed back to anxiously waiting scientists on Eanh. It saw river beds, craters. canyons. grear extinct vokanoes such as Olympus Mons, as well as obvious signs of erosion from water and wind. Following Mariner 9's sllccessful visit. in 1975 NASA launched the twin Viking missions, each one combmlng an orbiter and landcr. But that was It until the mId· Nineties. Smce then sever.1I robors have been senr to Mars, determined to be the first ro underpin the principles which will
one day allow humans to set foot on the planet's Sllrface. Satellites have included NASA's Mars Glob.l.l Surveyor and Mars Reconnaissance Orbiter, and the ESA's Mars Express,
p.1rachute 100 rovers [to Mars] and you would IlE'Ver find a fossil: lubrin explains. "Fmding fossils involves hiking through lots of terrain, it Involves pick and pickaxing work and it involves diligent work such as carefully splitting open shells to rind preserved fossils. This is way beyond th€' abihty of robotic rovers and if you're talking about whether humans
could setlle on Mars, then clearly, you have to send humans.' So to Mars humans must go. And in a change of dynamic, agencies and organisations are looking p.1st unmanned missions and instead are focusing on landmg the first man on the Red Planet in a step that makes SCleJlce fiction a reality. The feat has become a race onc€' again.
The Orion module replaces lhe C now cancelled Constellation Program asourfurure hopes to send man to Mars
•
Explore the Galaxies Zubrln thinks he knows how to win
the race. In the
Nilll.'l~
he d~loped
the crew out to Mars and because the return vehicle is waiting on Mars, they
a daring plan that he called Mars
don't need to fly to Mars on a giant
Direct. lhe basic idea of the Mars
spaceship, they Just ny to Mars in a habitation module that lands in the vicinity ot th~ Earth-ri!turn vehicle: After 18 momhs on til<' surface, the astronauts then head home In the Edrth-Ietum vehICle, leaving the habitation module on the Red Planet. But then a serond manned miSSIon is LllffiChed, deHY<':ring another habitauon module to the surfaCt', and th('n a third .md a fourth, "&>fole long you have the first human seulemem on another wolld: says Zubrm. "TheI'C is nothl11g in this that IS bl:'yond our tcchnology: we can do this." Ind('('(\, other organisations al(' clamouring to be the first. SpaceX's Eion Musk has aheady staled that he intends to go to MJIs, while
Direct mission is to explore Mars With a travel-light philosophy: he says
'Rather than buildmg gl.lnt spaceships loaded with all of the food. watt'L air, fuel and C»lygen required for a roundtrip mission, we lry to make the most important of these on Mars,· ror example, Zubrin proposes thaI an ullmanned mISsion go ahead first, carrying with it an Earth·return craft and the ability to make rocket fuel on
Mars by reacting hydrogen with the carbon dioxide in Mars's atmosphere
to create the methalll' and oxygen rocket plOpellant and oxicllser. ·So now you have a fully fuelled Earthreturn vehicle walting on the MartJdn surface: he says. "Then you $hoot
Manned
missions to Mars The leading cand1dates m the new race to Mars
"I do favour sending robots to Mars... but they are just the advance scouts"
1. Inspiration Mars
3. NASA
Wllh thl' IIlll'llIl"n "I 'l'mJIIlJ' J mJll ,llld ,I W(l]ll,lIl Oil wh,.1 ha'i lilt' I1hl~IIl/:' 01 ,I hi,tOlil mi""i'>11 1,I,tlTl!, 501ll,IV,'i, 11l'llII,lllon M.H' Illtt'IId'i te, sMt'11' rl'lul n ih lH'W tf' LlTTh afTel Th~y Ilv Wllhlll IhO kil{)ITlt'TI~' (JOO lTlill's) of Ilw 11<;,1 PI,IIlt'1. L1,ing T,'('lmologw, dl'rlw'l! from i'I,\S,\ dl1d 11ll' Illlt'111,IIIOll,11 Sp,lll' Sldli"ll I'll<' pl"11 I' 10 lIW Tlw gr,lVll,IIIOlh.1 IIlfhlC'I1U' "f MJlS To Shll/:S)wl Ilwil I1hlTlIWd >"('hltlt' onTo.1 l<'tllrn (OUIS(' b,ll~ t" E,mh, Tlll'\' wlii llol 1,lI1d'm MJIs. Till' ship, mUaT,lbl.. h,.hltaT nHldlll~ "illl.... dt'plowd ,lft"l I,Hll1lh _'Ild dt'I,KI,..d prior 10 1('-.. IlIT\{ IIlto ollr pl"lwI's alllH''iI')wr..
I'h,' N,lti"llal Al'roll.l\lTllS am! SI'Jll' ,\dnlllll';tr,lllolt J"ASA, IS Iht' wuTld 1t',ldt'1 III M,n, '-'X~llp['IIIOIl.lh 1l1',,,T lell'nl d..velopl11"llt 10 ,...nd hum.IIl' I" M,n, III ,I 21HO llIllt'franw i, _.bn elml'IITlv ulldt'r rl'VI .. W, (JTW ~"",ihdily I' tht' Olioll Mlllri-Plll)1llS" Clt'W V.. hltl~ th,11 W,IS ,1ImOlllll't'd b\-' :- leturn T" M,utidll "Iblt lI,illg 1lll'lh.1I1C' pro)lt'11,1Il1 111''',1.. from Mdl''> ,;<'IL lmag,,' J .,Iwws Ilw l..n'nT (Jllnll dlop t... ,t wl,..l.. 'i<,wnTlsls \I~d ,I 1ll<.><.k-lIl' of till' (lll"n lIl'W modult' to Slllllll,ltt' '"lTIO''' ""lier-I,mdlllg ... ,'11.111'" t" "ll(Ollnt fPl II,.. t1ltr,'rl'lli \'!.'I"ull<'s, p,.r,ld]lll~ dl'plo.... ln.. nh t'nTIY "Ilgll", "H, .. Il..lghts ,IIId wlI1d COl1dltions on M.Hs.
2.SpaceX ~p.Kl'X IS till' WLlIId'S llist I'rlv,lkly )wld C"mp,1Il\' 1'-' ,...1l<1 l,1Ige,1 To Th.. Illtem,llloll,.1 Sp,Kt' SI,.llon ,md 1l0W Tht' '-',ll11p,lIW', l"Ulld.. 1 ,md CEO Llnll ~lLJs~ IIlh'mts 10 "'1)(1 •• miSSIOIl 10 M,II'_ Fil,T Will bc'" >.IIlII'It'-ll'tlllll ml>SIOIl tJlll'tlllt'd [)r,l/:oll, th.11 Will •• 1'0 loo~ 101 'Ign, of lif.., It> long-krill pl,IIIS, howl'ver,.H" Tn ,,-'nd ,l nlollllwd IlII",iOIl T" M,ns III ,I modlhl'd H'r,IOIl of It, ,.iTe,ld\-, t",i1T Ilr,lgon l,lp'lIlt', I Iw ill!<,lltl
The NDX-\ sp.KeSult designed by aerospace engineer Pablo de l.eon for possible use on Mars. was able to l"Ildure the Icy temperatures and battering windsduJinglesls in Antarctica
4. Mars One Adamant lhatlhl' ll'l'hnol"!,ll'S to 1,IIUI lht' filsi h"nhlll'i 011 M.HS nisI lJukh ,t,m,up M,HS 011'-' dum T" spt'nd .Ill e"TlIll,lll'd $f, hillioll 10 mill,llI ... s,'ml f"ullnt!l\'ldu,ll, I" lilt' Ikd PI,IIlt't. Tlll'v Will I", T,.sh'd WITh ,...ttm!' up .I h,lblt,lbl .. "Utpl"t b,l>t'd nil It',,,,I\"'Ill.ld~ ll.Hdw,m' Ih,.1 willi"" ,...Ilt to IIll' pl,lI11't III dtl'''1I1''', Mt~1 IIlSl,.lIl11g tlll'1I hahlt,.T, Ilw nWllllwr, p( till' (lI,t lok>n ... "Uhldl' "f Llith will bt' exp,"-.Wd to grow Ih"lf own IO"ll. lIllIl<' l)ll'lI own ''",It..1 ,wd oxygt'll, pt'lfolm 1""',lIcll ,HId, or lOUI>t', ,'~pkHl' ,I wholt' Ilt'''' pl,ll",t
"SpaceX's long-term goal is to colonise tfie Red Planet"
...
..,,;;::::.:--
History of Mars exploration
58
1971
1976
1997
Mars3 This was the first spacecraft to achieve a soft landing on the surface of Mars but a great dust storm (Jused a communications failure.
Viking 1 & 2 The Viking programme reWIIle
Sojourner Sojourner was the first rover to touch down on Mars, It analy~ the atmosphere, climate and make-up of the planet's rocks and soil.
2004
2006
2012
Opportunity
Mars Reconnaissance Orbiter (MRO)
Curiosity Curiosity is providing
With a suite of instruments, the MRO c:ontinues to analyse Mars's weather and surface conditions.
information on the past and present habitability of Mars, as well as taking hi-res images of the landscape.
The Opportunity rover has found Martian meteorites. looked into geological processes and studied surface composition.
59
Explore the GalaxIes
Destination Mars former pm'ate astronaut Dennis Tito has launched Inspiration Mars, an organisation that plans to send two humans - a male and female. likely married - on a flyby mission of Mars in 2018. It's a plan that Zubrin himself pltched to NASA in 1995. but they didn·t take him up on the idea. "Really the key question of whether Tito is going to pull this off is whether he can raise the $2 billion needed: says Zubrin. "NASA is funded to a level of $18 billion per year. Now $2 billion is nothing to the government but it is a lot in the private world. but really if NASA had the courage of Tito we would have done this when I proposed it to them In 1995.' Dr Gernot Gromer of the University of lnnsbruck and head of the MARSl013 project agrees with Zubrin. "This is a truly ambitious plan.' he says. "If you look at their papers where they describe the mission profile. it is well thought through and written by experts who are very good in their subjects. However, for trajCClory reasons they have to keep the 2018 deadline: That's the big problem. says Gromer. Dennis Tito is only lunding the first three years of that profCl=t untllthe really high financial demand kicks in. Will they then
be able to get [he- financial backing that they need in the time required? "Developing a transportation system which brings people to Mars and back safely is something that will probably take more than the few years left to the 2018 deadline: adds Gromer. ·1 honestly wish them all the luck. but I am pessimistic that they can really achieve the super-tight schedule: Another proposed privately funded manned mission is that of Mars One. a not-far-profit organisation based in the Netherlands that intends to establish a permanent human settlement on Mars by 2023. by sending astronauts there on a one-way trip. The-ir plan is to gel funding by turning the adventure into a reality TV show. However. Gromer is less convinced by their plans than he is 01 fnspiration MJrs·s. ·Unlike the team of Dennis Tito. the Mars One team lacks the expertise and knowledge how to approach such super-ambitious progrilmmes: he says. "Just simply recruiting and maintaining such iI Iilrge ilstronaut corps is well beyond their cilpabilities. not to speilk 01 launchers. hilbitats. spaCt'Suits etc. Having big players like SpaceX [behind theml certainly helps. but there is no indication these are doing it for free. Thilt meilns. that even
"The basic idea of the Mars Direct mission is to explore Mars with a travel-light philosophy"
61
Explore t
"Inspiration Mars is a truly ambitious plan. It is well thought through and written by experts who are very good in their subjects" large TV companies won't be able to alford such a multi-year programme, not to mention lhl' challenge of keeping the public interest going for such d long time: In the meantime, as the various
companies look to lind the funds to reach the Red l'Ianel. full-blown
simulated t'x(X'ditiOllS 10 M.us .Ile laking place. For example, Isolated lor 510 days in a mock-up spact'Crilft
in Moscow. IiV(' crcwmcmbNs got the full blunt 01 what )( would really be like to be making their way to Joothc-r planet. The Mars-5(X) project sImulated Ihl' Earth to Mars shuttle
spnt·dcsccnt
62
craft and the Martian surface- DelVing deep into the psychologkal and medical effects that long.aistance spaceflight would cause. Mars·5QO Identified possible prolJlems and solutions that cosmonauts were likely to encounter. Subjected to peculiarities such as a lag in communication between 'Mars' and 'Earth', ratloning of food and having to live in an enclosed space with others for a long period of time, thl'Sl' Martian explorers were tested to theIr limits, While several crewmembers experienced problems sleeping. avoided {'xerase to counteract the effects of spac!" trav!"l and would hide away from
theu crew mates, Mars-SOO, which r.an between 2007 and 2011 and admitted three separate crews, proved a success. with most volunteers reportedly being in good physical and psychological condition, However, with simulated missions to the Red Planet far from over. experts want to put potential astronauts to the test even more, How
would they deal with completmg actual scientific experiments and walkmg for miles across the tough Martian terrain? For such an occasion there was the aforementioned MARS2013 project. which took place in February 2013. The month·long simulation was initially based at Camp Weyprecht
in the Mars-like Moroccan desert. before a three-
"The Mars One team lacks the expertise and knowledge how to approach such superambitious programmes" 64
The V~ Marineris canyons. iIlustr.ded here. cook! be of interest to future Martian explorers
,
involving 23 nations and more th.:ln 100 scientists. The team performl'd 17 scientific experiments, as well as field·testing new spacesuit designs and deployable shelters, acting out an astronaut-injury situation and testing cHff.climbing robots. Like Mars·500, a 20·minute 'lime delay· was lncludl'd in all communications with 'I::arth', simulating the wait as radio waves travel at the speed of light from Mars to I::arth and then back again. Data collected from such simulations is important in planning and preparing for the real thing.
And when IS that 'real thing' likely to occur? The Mars enthusiasts at Inspiration Mars, Mars One, the Mars Society and SpaceX would argue that it could happen by the end of the current decade, or the beginning of next Others, howevel. are playing it safer, and suggesting 2030 or later as the most likely date for mankind to reach the Red Planet. In the end it will be decided by who can raise the necessary money and have the rourage that ZUbrin says is essential to make history by being the first to send people to Mars..
65
I' ,i
! 's ~
f ~
~
-
Discover the Solar System At about ISO million kilometres (93 mlllion mill.'s) from Earth lies a giant mcandl.'SCl'nt ball of gas weighmg in at almost 2,000 trillion trillion kilograms and emitting power equivalent to 1million times the annual power consumption of the United States in a single second. Since the dawn of Earth <1.6 billion years ago it has been the one ever·present object in the sky, basking our world and those around us in energy and light and providmg the means through whkh environments, and ultimately life, (In flourish. We see it every day and rely on its energy to keep our planet ticking, but what exad\y is this giant nuclear reactor at the centre or the Solar System that we call the Sun? Over 5 billion years ago a vast cJoud of dust and gas was located where our Solar System is now. Inside this nebula something huge was happening gravity was pulling together the debris, likely the remnants of anothel star going supernova. Into one central mass. As the various metals and clements were brought together they began to fuse 1I1to an object at the heart of thIS nebula. This dense clump of matter, called a plOtostar: grew and grew in size until It reached a critlCal temperature due to fr\ctlon, aboul 1 mlllion degr('{'S Celsius (1.8 ml1lion degrees Fahrenheit), At thIs POint nuclear fusion kicked 111 and our Sun was born. At the heart of the Sun, hydrogm atoms fused together to produCt' helium. releasing photons of light in the process thal extended LhlOUghoul the Solar System, Eventually the hydrogen and helium atoms began to fuse and form heavier elements such as carbon and oxygen, which in tum formed key components 01 the Solar System. including humans. To us. it's the most important object in the sky, An observcl watchmg from afar, however. would see no discerning qualities of our star that would make it stand out from any of the ot her
70
hundreds of billions of stars in the Milky Way. In the grand scheme of things irs a fairly typical star that pales
in comparison
(0
the size of others.
For instance Sirius, the brightest star m the night sky. is twice as massive as
the Sun and 25 limes more luminous while Arcturus, the fourth brightest object m the night sky 15 almost 26
times the size of our closest star The Sun is located at a mean dist
million mlles) from Earth. a dIstance known as one astronomical unit
AU). This giant nuclear furnace Is composed mostly of ionised gas and drives the seasons, ocean (l
currents. weather and climate on Earth. Over a milhon Earths could fit inside the Sun, which is itself held together by gravltational attraction, resulting in immense pressure and temperature at its COll". In fact the
core reaches a temperature of about 15 million degrees Celsius (1:7 milhon degrees Fahrenheit). hot enough for thermonucle"l1 fusion to take plaet>. The intense physical process taking plJCe in the Sun produces heat and light that radiates throughout the Solar System. It's not a qUICk process, though: it takes more than 170.000 years for energy hom the cole to radiate outwards towards the outer layers of the Sun. Our Sun Is classlrlCd as a yellow dwarf star and these stars range in mass from about 80 per (ent to 100 pel cent the mass of the Sun, meaning our star IS at the upper end of thIs group. There are also thre<' further groups IntO which stars arc claSSIfied: Population I, II and Ill. Our Sun Is a Population I star. whlCh denotes thilt it contains more heavy
elements compared to other stars (although still accounting for no more thiln approximately 0.1 per cent of 1\S total mass). Population 111 stars are those that formed at the start of the umvefSC, possibly just a few hundred million years after the Big Bang, and they are made from pure hydrogen and hellum. Although hypothesised. no such star has ever been found, as the maJOTity of them exploded as supernovae in the early universe and led to the formation of Population I and 1I stars. the laller of which .are older, less luminous and colder than the former.
By now you're probably thinking our Sun is insignificant. but that's anything but the case. Being our closest st.ar, Jnd the only one we can study with orbIting telescopes. it acts .as one ot the grealestlaboratones available to mankind. UndersJandlng the Sun allows us to .apply our findings to research here on F..m h, such as nuclear reactors, and our observ.anons of distant staTS. Over the next few pages we'll delve into the reasons why studying the Sun is so ImpCITlallt and explore some of the amazing physics gemg on inside and outside this vast nuclear fuma.ce.•
"The core reaches a temperature of about 15 million degrees Celsius, hot enough for thermonuclear fusion to take place"
-
Discover the Solar System
Like the Earth, the Sun has an atmosphere, but the two are very different. The Sun's can be incredibly volatile with powerful magnetic activity that causes phenomena referred to as solar storms here on Earth Solar storms ale violent outbUists
of activity on the Sun that interfere with the Earth's magnetic field and
inundate our planet with particles. They are the result of outpourings of energy from the Sun, either in the
form of a Coronal Mass Ejection (CME)
or a solar nare. The former is a release of a large amount of materia!. mostly plasma. from the Sun while the latter
is a sudden release of electromagnetic radiation commonly associated with a
sunspot. While no dlJ'l'C1 connl'Ction has been found between CMEs alld
solar flares. both are responsible for
causing solar storms on Earth. The reason why these two events occur is due to the Sun's atmosphere and its turbulent interior. with dll of Its components playing a part in bathing
our planet in bursts of energy. The lowest part of the atmosphere. the part dirl'Ctly above the Sun's radiative zone, is the photosphere. This is the visible part of the Sun that we can see, it is 300-400 kilometres (180-240 miles) thick and has a temperature of about 5530 degrees Celsius (9,980 degrees Fahrenhelt). This produces a white glow although
from Earth this usually appears yellow or orange due to our own atmosphere. As you travel through the photosphere away from the Sun's core the temperature begins to drop and the gases become cooler. in turn emining lesslighl. This makes the photosphere appear darker at its outer edges and gives the Sun an apparently clearly defined outer boundary, although this is certainly not the case as the atmosphere extends outwards much further. Once you pass through the photosphere you enter the
chromosphere. which is about 2.000 kilometres 0.240 miles) thick. The temperature rises to about 9,730 degrees Celsius (17,540 degrees Fahrenheit), surpassing that of the photosphere. The reason for this is that the conve<:tion currents in the underlymg photosphere heal1.he chromosphere above, producing shock waves that heat the surrounding gas and send it flying out of the chromosphere as tiny spikes of supersonic plasma known as spicules. The final layer of !he Sun's atmosphere is the corona. This huge
Particles ejected from the Sun can cause fantastic light dlspbys at Earth's pok's. known as the auron borealis (Of Nortlwm ~.md
All about the Sun
tl>e._
How solar stonns work Vast amounts of radiation heading for Earth
- - • Explosion A solar ~re can relea5e up 10 6~lO·25 joules of energy .n it explodes
tnc SlriKe of the
from
Sun. The giant clouds of r.lJon ¥Ill partick5 can wke up to two d.ys to
"Once you pass through the photosphere you enter the chromosphere, which is about Z,OOOkm thick" expanse ollTWteri.l1 can stretch as fal as Sf'\'eral milliOn miles outwards from ~ surface. Oddly. the templ!fiJlure 01 the corona averages 2 million degrees celsIUS 0.6 million degrees Fahrenheit), lar hoIter than that of the phol:osphere and chromosphere. The reason for this is unknown; as far as we are aware, aroms tend to ITl(;M! from hLgh to low temperatures and nor
va Vl'ISiL so the process oIlTWrenal moving out of ~ Sun beyond the photosphere is 1101 urdt:rstood. On ~ phoI:osphere, dar\: and cool known as sunspots appear in pairs as a result of Intense magnetic fields. The magnetic fields, caused by gases moving in the Sun's Interior, leave one sunspot and enter another. Sunspot activity rises and falls on an lI·year cycle, as discussed In the next section. Someumes clouds of gases from the chromosphere will follow these magnetic field lines In and out of a pair of sunspots, forming an arch of gas known as a solar prominence. A prominence can Jast up to three months and may extend up to 50.000 kilometres 00.000 mill'S) above the surface of the Sun. Onct' they reach theil maximum height they break and erupt. in turn sending massive amounts of material racmg outwards through the ccrona.. an ('Vcnt whICh IS known as a coronal mass ejection (eME). When the sun's magnet.ic lick! is concentrated In sunspot areas. the resultanl magnetic fick! hnes can extend and snap. causmg a violent explosion on the surface of the Sun called a solar flare. At the 1T1OtllCf1\ of eruptlOll vast amounts of radlatlOll are emitted mto space. wtuch we call a solar storm when It reaches Earth. The parudes within a solar storm often Intcr.JCI WIth panicles m the alll~lEle at pIancts In the SoLu System. c:ausmg fantasllC dISplays of lighl al then poles as the gases in the pl.anefs allllospl....e are heated by lhe pamcles.. On Earth we Jr;ooo,y these as the aurora borealIS m the Northern Hemisphere and the aurora australis In the SOJrhem HemISphere.. regIOllS
tr.Jvel to the Em.
----.Cyd. Solar flares peak.,
lI·~r·
Iona KtiYity~.
The these cydes is unknown. In petil;xh of
C~
of
inactivity there un be less thMI one flare ~ week but when the Sun is at its busiest there an be severall!Wf}' clay.
- - - • Intensity SOlar wind typiCally travels at 1.6 milliOn kph (one million mph). but the aplosive event that emits a solar flare can send it hlKtling towards t/l@ Earth up to four limes faster.
- . Magnetosphere The magnelic: fl'tld StnOUndinc the E
lum auWla ~ to form ill the poles.
73
_..:..Di::,:scover the Solar System
The SORa mission
The Solar and Heliospheric Observatory was launched in December 1995 and is helping us explore the Sun
erview SOHO project scientist Bernhard Fleck tells us why studying the Sun is important to Earth 1. Understand life "ThE> Sun provides lhe energy for ~I ~fe on Earth. It seems quite natural tl1
2. Understand dimate "SOlar radiation is the dominant @O@fgylnputlntotheterrestrial ecosystem. The Sun provides a nalurallnfkJen<:e on the Earth's atmosphere and Climate. To understand mankind's roles In
climate change. the Sun's Impact must be understood:
3. Predict space weather
ThL> Solar and HeI~ Ob:servalDry. also known as 50110. was bunched on 2 December 1995.11 was built In Europe by prime COOlJaCtOr Matra Marroru Space. whICh IS now !::ADS AslJium. The spacecraft is operated JOIntly by the ~ and NASA. It studll'S the Sun In depth. a.1I the way from its deep COIl.' to ItS oute1 corona and its soIa.J Wind. 50110 is ma.de of two modules, the Servire Module and the Payload Module. The lormer prov1des SOlID with power. while the Ianer houses aU of the mstrumeTtls on the spacecraft. Ovl'rallihere are 12 instrumeT1lS on board 50110. mne of which are run by Europe as well as Ihree from the
Umted srales. SOIlO is located nea.r to Lagrangian point I. which IS a point bel:ween the Earth and the Sun about 15 million kilometres (930.000 miles) from our planet. It is the point where the gravitational allraet.lon of the Sun and the Earth cancel out. so a telescope such as SOHO can remain In a stabl<' orbit to observe the Sun. SOHO is one of the only telescopes currently
capalje ol detoomg mcom1ll8 sola' flares lhal could be potenually ha.zardous 10 satelhle5 and OIheJ eleruomcs on E.uth. Of the 12 InstIUments on board SOHO one of tile' most InterestlJ18 is tile' Larse Angle and Specnomemc Coronagraph (LASCOl wlUch studies tile' Sun"s mona by creallllg an a.mrlCiaJ solar eclipse. The LASCO mSirumelll has been latJeIy responsible lor lnadvcrtCfltly dl.SOM'nJ18 many cometS near the Sun. wilh OYer 1.800 lound 10 date. 5OHO has three pnrnary ob,ectlve5 that It has been carrying OUI since ItS launch. One of these was to invesllgate the outer regions of the Sun. speorlCally the corona. At the momentlt IS still unknown why the corona is hotler than the photosphere and chromosphere of the Sun, so it is hoped thai SOHO might help to provide the answer in the future. $OHO has also been used to observe the solar wind. and also to study the interior struClure of the Sun through a process known as helioselSlllology.•
·Our Sun is very dynamic dnd produces the largest eruptions in the SOlilr System, The5t' solal
uorms can reach 01,11 planet and .x!wrsely affect technologies such OK satellites and power ,rids. Space weather becomes
incre~81y
imporUnt as our society depends more 011 modern technologies."
4. Learn about stars "If we want to under'sund the lriverse. we h.iWe to undefsUind the evolution fA plu:iei. To LRHnt.nt pLaxlft. we need 10
LRlersUnd the evolution of sun that IIWke up the p1aJties. If we WMlI to ~ sun. we betler tn1erst41Od the Sun. the only stM we can resolve In II'M ~:
5. Stel~r physics ~b ""Tht! Sun lets us study basic physbI pbsma pnxesses under conditions tNt can't be reproduced on EOIIth."
On the scak' of sa.ar fLues. X-dass storms are most pl7Ntfful. SOHO took this ima8e on Navember 2003 showing the most powerlul t'o'eJ ~ wflich reiIChed X28
-
Solar edlpses are.l popular time tD view tlR SUn but USinJllhe CU1t'Ct viewin& equipment is very
Discover the Solar System
ImpOl1anl for ~
Observing
the Sun
Hwnanity has been fascinated by the Sun for thousands of years and even primitive records still prove useful. Discover more about the past, present and future of studying the Sun
Qbse",ations of the Sun have been used lor both scientific and religious ~rvatjons lor mlllennia. Civilisations havt' used the Sun
to kPep an accurate count Of days. months and years since at least 3OOBC. while scientists such as G
provide J rudimentary solar calend.u through which the Sun can be traced.
The towers, ('Jell between 7S and 125 square ml'lres (807 and 1.345 square feet) in Slle, run from north to west along a ridge along a low IIlll from an observation (XltnllO the west
of the ridge the Sun call be seen to nse and set Jt different points along the ridge, which allowed ancient civilisations to track the number of days 11 takes the Sun to mO\!(' from lower to towel. Much later. In 161l. the renowned Italian astronomer Gahleo Galilei (1564·164l) use
The history of
plesent on the Sun's sUiface at any onetimt>. Fast forward to today and. aside from SCI-IO. one of the primary telescoPE'S used to abservt> the sun is the Japanese Jlinode spacecrafL Hinode is a telescope in sun· synchronous 8arth orbit, which allows for nearly continuous obS(>rvation of the Sun. It was launched on II September lOO6 and was initially planrK'd as a three·rlllssion study of the magnetic rlClds of the Sun, but itS mission has since been extended as it contInues to operate nominally. Another important Sun-
observing the Sun 7B
the Sun, approaching to within just 8.5 solar rawl (5,9 milhon km, 167 million miles. 0.04 AU) after its launch In lOiB. It will probe the outet corona of the Sun In unpr('('('(Jented detail while also becoming the fastest spaceClaft of aU time in the process at up to 200km per second (1l0 miles per second), Apart from million dollar tel~pes. many amateur asttonomers around the globe today observe the Sun either for entertainment or educational benefit, Using specially designed glasses people can look at tlK' Sun from Earth. although caution must be taken to lima time spent looking ar. the Sun and it should never be Jooked at with the naked eye. Other methods of SOlar obselVation include using a
telescope to produce a trace of the Sun, J method Similar to that used by AristOtle and his camera obscura in the 4th Century BC. Again, precautlOns muSt be taken hen', as under no circumstances should the Sun be directly observed through a telescope. Whatever the method. and whatever the mISsion. observations 01 the Sun have been a long tradition Jnd will continue to be so for the foreseeable future. ASllooomkal events such as planetary transits and solar eelipses provide amateur astronomers WIth opportunities to S('(' extraordinary solar phenomena, while agencies throughout the world will continlK' to study the Sun and learn more about how the fantastic star works.•
"Civilisations have used the Sun to keep an accurate count of days. months and years since at least 300BC
.400BC The world's oldest solar observatory, the Thirteen Towers of ChJnkillo, is built in Peru to track the motion of the Sun.
• 350BC Aristotle uses a CJmera obscura to project an imJge of the Sun and observe a partial eclipse,
.1612 Galileo Galilel uses his telescope to make one of the first observJtlons of sunspots on the surface of the Sun,
--
All about the Sun
Different ways to observe the Sun On Earth we ))elceive the- Sun to
the large majority of our images come
be (I yellow ball of gas in the sky but like anything as hot as the Sun. it is olCluiilly closer to being white hot when viewed from sp;:!Ce. The!e ,ne several telescopes currently observing the Sun but
from the STEREO telescope and
the solla observatory, both in orbit
around the Sun. By viewing the Sun in different wavelengths we can study its
different characteristics and see some of its main features in a diffe/entlight
Ultraviolet Images of the Sun in ultravHJ~t light are between wdvelengths of aboot 19.5 and 30.4 nanometres. Such an im
Sun's chromosphere,
Visible ViSible light images commonly refer to those viewing the Sun in white light. which shows the true colour of the whiu··hot Sun. In visible light images we can see the Sun's photosphere, which is about 6,000 degrees Celsius (10,832 degreE' Fahrenheit) and therefore appears whlte·hot. Here, we can see dark spots on the Stlrface of the Sun, known as Stlnspots.
X-ray Light with a wavelength shorter than ten nanometres (ten billionths of a metre) Is known as X·ray light. X·rays are emitted from the Sun's corona, the hottest visible layer of the Sun's atmosphere, The visible areas of brightness are places where more X·rays are being emitted, around areas of increased ilCtivity on the Sun's surf.lCe.
Infrared Infrared light is responsible for more than half of the Sun's power output, typically around wavelengths of 1,080 nanometres. Infrared Images show features of the Sun's chromosphere and corona. The dark features on the image are areas where the gas is more dense, absorbing more infrared light than in other areas.
I
.1749 Oaily obsef\/atlons of the Sun begin at the Zurich Observatory in Swiuerland.
I
.1849 New observatories around the world allow continuous obsef\/ations of sunspots to be made.
I
.2006 The Japanese telescope Hinode is launched to study the magnetic fields and atmosphere of the Sun.
I
.2010 NASA launches the Solar Dynamics Observatory. its primary goal being to study the Influence of the Sun near Earth,
.2018 NASA's new Sun·observing telescope Solar Probe Plus will launch and become the dosest spacecraft to the Sun.
79
. , ..• ~.
.. !".
•
..'"
-
·!;cover the,
Moon colonies "America's challen,ge 01 t0d3y has forged man's destiny of 1OlTlOrTOW: said Apollo 17 astronaut Gene ~l11iIn as he stepped back into the Lunar Mcxlule wllh fellow astronaut .Jack Schmllt on 14 December 1972. The Apollo llUSSlortS were expected 10
IOCkslart an • of human ~ explor.ltion. indudtng lunar colonies.
manned Mars missions an:! posstiy ventures beyond. But four decades Ial:et:. and IIx! PIPE' dll'ams of 2OI:h Cenl:ury V!SlOOo)nes seem funher away than that fateful firsl: Sl:ep in 1969
Irs no exagger.ltJOO to say thaI. in the year 2012. many had pt'dicred space to be teemmg WIth human hll!. The fact thaI irs not s.M' fa oil handful of astronauts aboard an orbnlns space SLltion. is a disappomlI11el1l to many a space enthusiast. 8m is it really all doom and gloom? Are we truly destlJlE'd 10 remam COflSlr.lined to our Blue PLmet left (0 observe the Moon from afar rather than sel:lilli i0oi:. and wing. where only a dozen men have done so befon!? 'If somethmg can be done. II ub.unalely Will be Silys Dr Paul SpudIS. talking 10 us about the possibility of a future Moon settlemcnt. "If Oil SOlTll.' pomt il makes scnse for the Moon to be IX'Tmal'l('ntly inhabited. then it will happen: Dr Spudls is somewhat of an expefl when it comes to lunar exploration.
done:
He is currently a senior staff scientist .:It the Lunar and Planetary InstItute
in Houston, Texas. and has worked
on both the Indian Chand!Jyaan Moon programme and NASA's Lunar Reconnaissance Orbiter. H{' also served on a Whiw House panel 10 analyse a return to tix' Moon and the estabhshment of a lunar base. From tix' outsidl' Iookmg in a posslble Moon colony might SC('m improbable. if 001 Impossible. but irs an Idea that has been sttggested by scientists SIJ1Cl' Iix' dawn of the space age. includmg Dr SpudlS himself ·1 advocate a TC'lum to the Moon to use n for the creation of a new 5p
83
-
Discover the Solar System The refelence of water on the Moon is an important one. and is onl' of thl" primary T&\5Cln5 Ihatlunar eltp!orauon
has ~ such an intriguing talking point once agam. TIlE' discovery
ofwat(>f on the lunar surface was fOimally announced by NASA on 24 St'ptember 2009. Found by thi:'
Chandrayaan-l orbiter and impact probe, it was a huge announceml'nt wIth faHeaching ramifiutlons. As Dr Spudis mentions, water
IS a vItal ingredient for any form or manMd space explOration. It's !'55ential for llfe, and its conStlluents (hydr<)g('n and oxygen) also happl'n to be the primary components of rocket fuel Previous vislorls of a lunar base envisioned oJ colony constantly resupplied by missions from Eanh. a rostly and tUlIt']y endeavour that a
multinational mission would suugg\l.> to accomplish, Ie! alone one nation going it alone. Ttli' discovery of water on the Moon, hidmg as Ice in the shadowed and cold rroches of the
deepest JunJl craters. raised the very real possibility of a lunar colony being Sl'lf-sustaming. rather than rehant on resupplies from Earth, 'Water on the- Moon is tlll' most important discovery for spacenlght since thi.' rocket equation: explams Dr Spudls, 'It means that we can learn how to 'hvc off lhe land' on the Moon, an essential sklU for any SpJCC'Fanng species.' It's not quite as easy as l.Jndlng on the Moon and scooping up buckelFuls of waler, however. While water ICt' ('xist.s, us quantities are up for deb.lte. The !owest estimates place 11 at makmg up lust 0.00001 per cent of a portion of lunar soil. sparser thJn the driest deserts on E.1rth Upper estimates suggest a quanllty of 85 per rent, a much more uselul..,mount If COllect. In March 2010. Chandrayaan·1 agam mdde.m Important discovery, this time llnding 40 permanently darkened craters neaJ the Moon's poles with a potentiaJ 600 million metric tons (1.3 trillion pounds) of Willer ice If the upper eslimate holds uue.
Dr Spudis highlights the need to quantify how much waler icc Is
available to ensure the success of a lunar colony: "Although we koow thaI water exists on lhe Moon, we have many questions "boDr Its physical stare and how It varies in conc:entli1tion. We need ro prOSpl'(t and map ice deposlrs, eXIT..,ct some water to delermine how dlfficulrlt may be, and use il in space to completely demonstrate the use of lunar water from an end·to·end systems engineering basis,' Whatever the true qUilnrlty of water on the Moon, the possibility of colomslng rhe Moon ls not only exciting but also incredibly useful. From a purely fmaada.! perspel:tive. the plOSpectS misht set'm bleak. F..stlmatcs suggest a lunar colony would cost upwards of tens of bIllions of dollars. an amount of money simply not available to any space agency in the world. But the parenti"l returns are huge. in the form of job creation, new mventlOns and bener rechnologl('5. POI every dollar invt'lited in the Apollo miSSion, it 15 saJd that around 20 dollars were remmed to the American economy. The prospect of a permanent residence on the Moon would only Increase the porenl1a] rerum, And rhis is befole we even consider the exislence of helium-3 on rhe lunar surfa«>. an isotope blasted across the Moon by solar wind rhal could be the key ingredient to creating fusion reaclors, and Iherefore huge sources of powl'r, on Ealth. lIumanity is not JUSt a species drivl'n by money. though, despite what some would have yO\.! believe. We are inquisitive, curi01.1S, and we constantly strlve 10 furthel understand the natural world Mound us and the umvelSE' as a whole. COnfining O\.lr~lves to our world and failing to invest lJl manned sp.lCe e.xplorallon wO\.!ld be akm to giving up on OUI natural habits. to learn, and would relegate us b.lck to an age where humans merely looked upon the stars with fondness, rather than the rhought that rhey could be explored.
"Technically, we're not far away from returning man to the Moon ana creating a Moon base" Dr Paul Spudls. seniorstaffsdentist. Lunarand Planetary Institute 84
History of Moon exploration
• r
3 Feb 1966
luna 9 This Soviet 'cralt was the lirst probe 10 land on the Moon al'ld return surtlce Images.
• r
30 May 1966
Surveyor 1 The first StKcesslul unmanl'led American Moon landing returned 11,000 pictures.
l.
20 July 1969
Apollo 11 Neil Armstrong and BUll Aldrin were the first humans to set foot on the Moon,
.11 Dec19n Apollo 17 While the last humalls on the surface were Americans Gene Cernan and Jack Schmitt.
_ 22 Aug 1976 Luna 24 This was the last spacecraft to date to land on the Moon and return lunar samples to Earth.
r
8 Nov 2008 Chandrayaan-1 This Indian probe found water olllhe Moon. and released an impactor to Ihe surface.
Moon colonies
-
Privatising
the Moon
The besl: WiJY to coIorusl' the Moon mighl be ID INhse the commen::ial benefItS of il, ~ seulement expl'ft AI Globus told us. Globus has (l"evxlUSIy woRed on the ISS from Earth and. alongside betng chairman of the N.a11Ollil1 Space Sooety's Space Setllefneont Advocacy Commlltee. he IS a big proponent of ~ seulement and has WYil:ten many paJX'fS on lhe subject. By the end of the 2010s. Globus said. governments around the ~ wiD haw a number of landers and
orollers OIl and around the Moon. The big change in manned space
exploration, however. will be the huge growth of the private sector. Suborbtlaltourism (with the hkes ol Virgin Galactic') willl4ke-off. with O'Ier LOOO people a Y\'ar reaching space by 2020. The next two decades will see luna.r mming companies begm to spring up
on the Moon. he continued. although they cook! struggle financially at first The key For their success will
be the growth of the space tounsm Industry; even though the ISS will be
d<'COmmissioned in the early 20205, space hotels will be launched into Earth OIbil and expand the priville
space SC'Ctor. Over the next 50 years the number of spdCe tounsts could grow to millions. no! jusllhouSolnds This. Globus saKI. IS where privatismg the Moon will be key. Mining
rt'SOUrces from the IUndf
surface. such as water, could provide essential supp1Jes for these hol.els.lt11 lake a while lor IUThlf mInes to become profitable. but by the 2070s they could be supplying mosI of the m.Jten.l1s IX'Cl'SSolry lor spact' hotels. Furthermore. If NASA or aoother agency mnsuucts a lunar m.JSS dm'el' on the' Moon. whICh would allow for cargo to be sentlwck to Eanh. then Gtobus s.u:I the kmar mmlf13 business wd\ become exlremdy profitable. a1k:Iwi.ng I( to potentially dormNte the metal markets on Eanh.ln ttlt 2050s these mines would need a crew of jus( 20 people. b.rt by the 2080s I~ could be lhoosaods fA people hVlng on ttlt Moon.loti Oper.lllng them.
The colonisation of the Moon IS a vital stepping stone in our grandel scheme of E.'xploratiOll. That's not to mention thE.' constant threat our planet is under from extinction. It's easy to forget that lust 65 million years ago, a mE.'rE.' 1.<1 per CE.'nt of our planet's 4.5 billion year E.'XlStE.'nce, an asteroid Wiped out almost every liVing thing on the surface. We know that there's no impending impact event, but one is likE.'ly to OCCUi at some point With no other·world colonies to inhabit. we are doomed to extinction. 'The Moon SE'rves as our nrst ·off· shore CO.lling station' on the oct'an of space: agrees Dr Spudis, 'We can USE' its material to fUE.'l a permanem transportation system. one that allows us to not only access the Moon and explorE.' it in detail. but more importantly, to routinely acct'SS all of cislunar space [thE.' zone between thE.' £arth and thE.' Moon], whE.'rE.' all of OUi satellite assets reside, The Moon is also a maiOl scientific fCSOUlce lx>cauS(" it records in detail a period of Solar System history thal has Ix>en erased from the Earth: So. If IV(' IV('re to decide to build a lunar colony. could it be done?
as
"From a policy perspective, we are light years away, mainly because few people recognise the value of the Moon" DrPaulSpudis 'Technically, we're not far away from returning man to thE.' Moon and creaung a Moon baSE' at all: says Dr Spudis. 'We have all the individual piecE'S and tcchnology IV(' would neE.'d to live and work on the Moon right now: Technology, however, is 1101 the problem, explains Dr Spudis: 'From a policy perspective, we are light yeaJs away, mainly bE.'cause f{'W people recogniSE' the value of the Moon as 1 have described it here. I am trying to change those mispercepuons: Many agencies have carried out studies into the feasibihty of a lunar colony, reaching as far back as 1959 wt\{'n the US Army first established a plan to build a fort all the Moon with two astronauts. Known as Project llorizon, it would have required about 150 separate rocket launches, maklOg it unattractive from a cost perspective. Various proposals have followed, and in the 21st Century numerous countries have at least announced their intentions to build a base on
the Moon {see 'A small step' baxout on page B4~ including Japall. Russia and ttK' USA.lt is NASA, however, that has carried out the most research in the area. For example, it has bE.'en testing its Lunar f,.lectr!c Rover for several years now and, while it might be repurposed for use on an asteroid rather than the Moon, it could providE.' weeks of habitation lor astronauts on ttK' Moon if deployed. All forms of research, though, have focused on visits longer than the Apollo missions (so over three days) but nO!: quite at a level of permanent habitation. As Dr Spudts E.'xplains, we still havE.' problems to overcome If WE.' are to coloniSE' the Moon. "Although we understand how to extract and use lunar resources in throry, IV(' have not done so in practice: he says, "The biggest need right now is experience: in aCct'SSing and surveymg thE.' lee deposits. in digging up the Ice and processing It into water, in converting that water into its gaseous
components, in cryogemcally freezing the gases into liquids and, finally, using the producl in a variety of applications, We understand how to do all these thmgs in theory, we simply IlE'ed to learn to do them to learn where the problems are: Overcoming these problems and testing key technologies are imperallve goals if IV(' are to achieve the ultimate dream of building a settlement or colony on the Moon. There's littJe doubt, however, that positive progress is being made in many of the necE'Ssary areas by several nations around the world. Lunar COlonies are I10l just the fancy of space vlsionalles any more; they will playa useful and important role in our continued exploration of the Solar System, and provide us wlth an off·world habitat the likes of which have never been seen befofl'. 'J beheve that the Moon is a critical enabling step into the Solar System: says Or SpUdlS. ·It is a stepping stone to space capability:.
The rings of Jupiter
--
::::.mown
What are Jupiter's rings
made of. how big are they and how were they formed? Halo ring
The mennost hiIo m, wetehei from around 92.000km (57.000 miles) to just over 12O.000Iun (78.000) and is the ttQest of
Jupiter's mgs tkough the verticA n's stwped like oj tOf\l5 ¥Id is slgMlCMltly less bright tNn the ~ rWl& despite ~ nwny Unes wider and lhickel'. The dust P¥ficIes that the H.JIo mg is oomposed of are less llyn 15 rricrometres in diameter.mll are mostly derived from the main ring.
Main ring TN!; narrow ring is just 6.SOOkm
(4,000 miles) wide and slfetches from 122.500km {76.000 miles} and 129.000km (80,OOO miles). It's the brightest of the rings and fringes on AdriIst~.
the smallesl of Jupiter's rOOf
innef moons. The main ring's dusty composition isn't evenly dlslrlbuted and is divided into regions of varied
thickness mal saner Nghl more effectively than the other rings. Still, it W3S faint enough to be missed by the Hubble SpiKe Telescope and witSn', detected until Keck viewed it in 2002.
Amalthea gossamer ring The Innermost gossamer ring runs from the border of the main ring 10 around 182.000km (113,000 miles), decreasing in thickness towards Jupiter. The ring gets its name from the Jovian moon Amalth@a,a 160km (99 mile) diameter rock that orbits right through the Cefltre of the Amalthea gossamer ring. AS it passed through the gossal1'lE!r rings in 2002, the Galilro spacecraft detected snwll bodies of ~s than Hun (0.6 miles) near Amalthl!a, whid1 are likely the debris caused by numerous colliSionS.
Thebe gossamer ring Lil:e Jupiter's other rings, the Thebe gossamer ring is composed of dust from imp.Jcts with the ..IoYian mooos. h's the faintest of the rings aod stretches far out to the orbit of the moon of Thebe u n6.000km (140,000 miles). However, scientists are ~ to ~ the extensb'1 of the Thebe ring's orbit. which couIcl be due to the int\.Ience of Jupiter's magnetosphere or even objects on the outside of the Thebe ring that are as ,.t~
95
f
Alien volcanoes on 10
--
In 1979, NASA's two Voyager
spacecraft flew by [0. the fourth largest moon in the Solar System and the innennOSI of Jupiter's four main
Galilean moons. and returned some staTlEng information. While moons in
the Solar System were once thought to be lifeless hunks of space rock. both spacecraft had directly observed
vokanic features on 10. Bearing more resemblance to a pepperoni pin.a than a giant moon. it was apparent thalIa was one of the most fascinating ilnd significant objects in our Solar System. Our own Moon is one that appears to have been active in the past but has quietened down to become
almost entirely dormant. retaining little to none of the volcanic activity that once sculpted its surface. Indeed only a few planets. Earth included.
Volcanic plumes on 10 can tower JOOkm (t9O miles) in height and reiCh half the speed thai would be needed to escape the gravky dtheIDOOD
have changeable environments at all. making the discovery of 10 all
the more exciting, Where once our Solar System was regarded as an ever· present museum of the past. moons such as this one have proven that it is still a lively and effervescent place. So what is it that makes 10 so amazing? To date. 10 has more than 400 known active vokanoes, making it the most volcanically active object In the Solar System, even more so than Earth. Dozens of vents are strewn across its surface leaking gas into the atmosphere, while at its poles and even occasionally close to the moon's equator vast icy plains can be found. The remnants of lo's volcanic past
and present are as clear as day, with large volcanic rings the size of California encirding either dormant or active vokanocs. While data lrom the Voyager probes. and later the Galilco spacecraft, has shown us volcanic plumes erupting from the surface of the moon, we are also able to discern some of lo's erupting monsters from observations on Earth. Some vokanoes have even been active for over two decades, meaning that the driving force below lo's surface is even more violent and ferocious than once thought. The reason for lo's outbursts of activity is that it is being battered
and bruised by Jupiter and its other moons. 10 sits at a distance of 420,000 kilometres (260.000 miles) from Jupiter, which might sound quite far away but consider that our own Moon sits 385.000 kilometres (240.000 miles) away from us and that Jupiter is almost 318 times more massive than Earth, while 10 is almost exactly the same size as our Moon. For this reason it"s obvious that while the Eanh exerts a small but OOliceablc force on the Moon, causing it to become gravitationally locked to our planet only a billion or so years ago, Jupiter is elrerting a huge force on 10. This moon, which itself is gravitationally locked to
99
-
Discover the Solar System Jupiter, is being constantly pushed and pulled by the huge gas giant. which in tum is churning ltS Insides. Add into this that the OI:her three Galilean moons, of which 10 is the second smallest but the closesllo Jupiter,
also ('xeT{ a gravltational influence on the poor moon, and you might start feeling sorry lor this troubled spare rock. The influence of the other moons means that lo's orbit around Jupiter is eccentric. with a difference of 3,400 kilometres (2,100 miles} between its closest and furthest points. So, l'Ven though the same face always pomts towards Jupiter, 10 experiences huge
~--.Heat The tidal fIe~ing heats lo's interior in the same way a paperclip warms when you bend it, The heat escapes through powerful eruptions
Tidal flexing on 10 Europa • la's orbit is not circular due to the gravity of neighbouring moons Europa and Ganymede
changes in gravItational force from this big bully of a planet.
In fact, the force on 10 is so intense thaI its solid surface acts in a similar
manner to oceans on (,;arth. It bulges up and down by as much as 100 metres (330 feet) in places, compared to 18 metres (GO feet) for the highest udes on Earth. Bear in mind that lo's tides are made of solid rock and those
on Edrth are made of water, and you might realise just how tough a time this moon IS having. These tidal forces neate a huge amount of heat in lo's Interior. and therefore the majority of its subsurface crust is a liquid. This liquid is under intense pressure and looks for any escape route possible out onto lo's surface, be it In the form of a volcano, geyser or vent This makes the surface a constantly changing place, with plumes of sulphur dioxide snow ejccl1ng all over it. Any meteorites that hit the moon instantly set' their impact craters filled with lakes 01 molten lava from the interior, The composition of this lava is still somewhat of a mystery but the two main throries suggestlhat it is either made from various compounds of molten sulphur or silicate rock. The former would account for the odd colouring olthc moon, while the latter would belter explain the hot temperatures under the surface where it may be too hot for sulphur to exist. As more missions are sent to the Jupiter system we will learn more about this fascinating and mysterious moon. NASA's solar· powered space
100
Emptical.
_---''<-_J
Because of its elliptical orbit. 10 is stretched and twisted over regular time periods
• Stretched
Biggest volcanoes on 10
10 experiences more tidal stretching from its host planet than our own Moon due to Jupiter's massive size
The strength of volcanoes on 10 is measured using the gigawatt a unit of power equal to a billion watts. For comparison, ten gigawatts is approximately equal to the power the Space Shuttle produced at lift-off
e
•
>10,000 GW (gigawatts) .1,001'10,000 GW
•
10H,000 GW .n-l00 GW .1'10 GW
••
•
Alien volcanoes on 10
--
Mantle-i
The mantle of 10 is thought to be made of a magnesium-rich mineral called forsterite_ while up to 20% of it may be molten
. . . . . .- -.......
, - - - . Temperature The surface temperature on 10 ranges from -180'( (-290"F) to -140'( (-220'F)
r' .
l---.Size 10 is slightly ~rger than our own Moon with a diameter of about 3.600km (2,240 miles)
IO'sother ~
features
• Core Measurements made by the Voyager and Galileo spacecraft suggest that at lo's centre is an Iron-rich core
.• Uthosphere The upper portion of the mantle, the lithosphere, is made of basalt and sulphur deposited from the various volcanoes on 10
Freezing (old One of the most astounding things about 10 is that, despite the number of active volcolnoes on its surfolce, it holsol molximum surfolce temperolture of -140'( (-220'F) This is becoluse lo's oltmosphere is incredibly thin, with volcolnic gol5es instolntly freezing and condensing upon eruption rather than adding to the atmosphere like on Earth.
Ughtning storms lo's orbit sees it cut across Jupiter's magnetic field lines, turning the moon into a giant electric generoltor.ln fact. 10 generates about 400,000 volts across itself, in turn creating 3 million amperes of current. This makes its woly bade along Jupiter's magnetic field lines olnd causes lightning storms in its upper atmosphere,
Magnetic field The magnetic field of Jupiter also has another effect on 10. As it sweeps past the moon it actually strips off about I,OOOkg (2,200Ib) of molterial per second. which in turn becomes ionised and formsol ring-shaped cloud of radioltion. The ions in this ring create auroras at the planet's poles, and also inflate Jupiter's magnetosphere to twice its expected size,
101
Hurricanes bigger than Earth E.1sIly ~ of t~ IT105l famous SUlrmS in I~ SoI.ar SysI:em. JupUer'S Gre.J( Red SpolIS so larae lhal II IS vISible through many Eanh-b.lsed feIescqJes. The Greal Red Spol is lhougtllio ~ been in uiSlera lor ar ~ 340 years. The oval red t')'e lOlal.es in an antkIockwiSe direction dul! 10 the crushing tugh pressure on the planet
5ln.'am 10 its south and a \~ suong wt'SIward jet flowing info its north. the Grt'at Red Spol: bas uilvelled several limes around Juptler. bur how dxl such a behemoth 01 a S10rm come ID ilppl'aT on the gas gIaIlt's surface? The answer is nor tINT aI this time despite the efforts 01 pIanewy scienllsls auempung to unravel the
Winds an ~ O'<'ef 400 kllornetres per Inn (250 miles per hour) oIrnund lhe spot. howeYer.lnsicIe the ~orm they seem to be ~arly l'IOneXJS(ent And that's nor all thiS mmpliclled weather system has an average temperalUrt of about ·162 degrees CelsiUS (,260 degrees Fahrenheill At around eight kilometres (fi'o"! mIles) above the surrounding clouds
answers.. HoweYer. whaI experts do theonse is that the storm IS dnven by an internal heat SOlIret'. and it absorbs smaller storms that fallmlO its path. passing over lhem and swallowing them whole. Anolher thIng that
..nd hekl
in place by an eastward jeI:
t~ also know
15 thallhe Great Red
Spol hasn't .. !ways been Its current
diameter. In 2004. ast~ oouced lhal the greal. storm had around half the 4QOOO·kilometre
The science of the Great Red Spot
as,CXKJ..mdl') dlametel thai 11 had around 100 yeaB before. If the Gre.al Red Spec CCI'IllnutS to downsIZe at Ihls rare. II could ~l\wlty morph from an ov.al shape UllD a more drcuLtr Sl:orrn by 204Q You mighl IhUlk lhallhls well·kOO'Nfl leature won'l bt st.::klng around lor long as I
b«omes sm.tller. bul experts belJe\o1! lhat thie great.age-dd storm is here 10 51011)' 51nct' II Is strongly powered by numelOUS other pheilOU 1t'n.1 in lhe atmosphere .around if. 5Iorms like these.are 00l out of place 00 Jupller. whose atmosphere Is a zigzag paltem 0112 jelSlreams. with blemlshts of warmer brown and cooler white ovals In the alTT10sphere owm [0 5lOrTTlS as young as a few houB Of Slrel:chlng mto centuries. •
~------ • 1. A constant twirl Hot pses in the psgiaot's atmosphere are constantly swirling around and rising and falling
~ 1---,-,1-,.---
4. High wind •
speeds Winds of the
Great Red Spot (i1n readl DV@f400lunJh
(2SOmphl
•
2, Falling cool gas Cooler gas falls down through the atmosphere, and what Is known as a (orlolis force causes the area to start whirling, creilting eddies that Ciln last for a long time since there is no solid ground on Jupiter to creilte frictlon
• 3, Shifting and
merging eddies
Inler.lClions with other SlOmI5 could give
Created eddies iIIe i1bll! to move i1round i1nd ITM!fge into OOII! MICIIher. creating bigger and more powerful storms
the Great Red Spot its monslrous t'neIJY
109
Deadly weather in space
Deadly methane rain With a surface pressure almost one and a half urnes that of E,;arth's. Titan's atmosphere is slightly more massive than our planers overall laking on an almost chokingly opaque haze of orange layers that block out any light thalllies to penetrate the SJturnian moon's thick rover Titan is the only other world. other than Earth, where liquid rains on a
solid surface. llQW{'ver. rather than the water that we are used to falling from the skies above us, pooling into
puddles and flowing as streams and rivers. this moon's rains fall as liquid
methane -liquid hydrocarbons that only experiencing rainfall around once every 1.000 years on its ,uid equator. add more fluid to the many lakes and oceans thal already cover the /lowever. these rain showers certainly surface. And it is thanks to the moon's make up for the lack of activity by dumping tens of centimetres or even complex methane cycle, similar to the natural processes found on Earth, that metres of methane rain on to the this is possible. Titanian surface. Rain fans quite frequently on ~..._ . . . .~ At the poles of the moon Earth, however, the same its a completely different can't be said for some story, however. Methane regions on Titan. rain falls much more frequently, replenishing Springtime brings the lakes of organic rain clouds and showers to Titan's liquid covering the desert with tll<> moon Titanian land. •
Titan's lakes and rivers of liquid hydrocaJbon are thought to be fed by methane rains brought about by the moon's complex met.hane cycle
111
Sights of the Universe
Winds at twice the speed of sound We've all got slUek out in or witnessed very strong willd.s here on Earth, from gusts that turn your umbrella inside out to tornadoes that rip up everything in their path. You might think these winds are a force to be reckoned with but unless you've had a day floating around the gaseous atmosphere of ice giant Neptune you haven't seen anything yell You might think that Neptune's distance from the Sun. which creates temperatures as low as ·218 degrees Celsius (-360 degrees Fahrenheit), would mean a world frozen solid by the subzero climate with not much going on in terms of weatheLliowever, you would be incorrect. The winds that race through its hydrogen. helium and ammonia·laden atmosphere can
reach maximum speeds of around 2,400 kilometres per hour (1,500 miles per hour), making this dark horse probably the most violently stormy
world in the Solar System. and making our most powerful winds look like
light breezes. Neptune's fastest storms take the form of dark spots, such as the anticyclonic Great Dark Spot in the planet's southern hemisphere and the Small Dark Spot further south thought to be vortex structures due to their stable features that can persist for several months - as well as the white cloud group, Scooter.
So what causes these winds? Neptune might be extremely frosty, but astronomers think that the freezing temperatures might be responsible: decreasing friction in the gas giant to the point where there's no stopping those super·fast winds once they get going. Delving into its layers of gas, we filld another possibility pointing to just how these active storms came about as the temperature starts to rise. As things get more snug closer to the centre, the internal energy could be just what is driving the most violent storms that we'Ve ever Witnessed.•
"The most violently: stormy world in the Solar System'
Long brighl clouds on NeplUne's surface are similar 10 cirrus clouds on Earth
The gas giant's alTnosphere as imaged by
the Voyager 2 spacecraft in 1989
What happens inside a star?
What happens inside a star? counteracting sequellCe where the star's Intern.l] pressure gradient pushes
against and counteracts the force of gravlty. In E'SSence. this determines the stability of the star's shell structure,
its various rings of material (such as plasma) and forces emanating from the core. Without this stability, the
various shells of the star will either contract or {'x.pand. For a star like OUt Solar System's Sun, the hydrostatic
balance is finely tuned. as the stdf has been stable for over 7 billion years. However, for a star such as red supergiant Betelgeuse. it is not. hence the uneven shell structure. The second key physical process
within stars is energy transportation, which is important as the temperature of its gas determines the denslly structure via its hydrostatic equilibrium. The transportation of
energy within stars can happen via two processes, either by radiation or convection. In main sequence stars ~ such as our Sun - these processes are typically localised in radius to speafic zones. with their position determined by the star's mass and shell opacity. Stars with masses over seven times thaI of the Sun are convective in their inner layers, while radiative in their outer onl'S due 10 their high inlernal mass. In contrast stars with iow mass, tend to be radiallve In their Inner layers but convective in the outer layers as their opacity is lessened due to theIr lower mternal mass. Finally, the third key process within stars is nuclear fusion, a series of reactions which occur prim.nily in the star's core (see the 'Fusion power explained' boxout for mort' information~ These fusion reactions necessitate high tempelatures In excess of 10 million degrees Celsius (18 million degrees Fahrenheit) and
power
explained Proton-proton fusion
While the surface of a star - known as its photosphere - appears a busy place, it is nothing compared to its interior, which is a hive of physical processes first, ther€' is the process of hydrostallc equilibrium. which largely determines the star's denslly structure and IS a
Fusion
high densities greater than hundreds of grams per cubic centimetre. Interestingly, the more massiY<' a stal is the shafter its life sp.ln becomes, as the nuclear fusion in its core occurs at a far quickellate despite the Increased quantity of fusionable matena!. As such, stars of similar size to our Sun will haY<' a main sequence of apprOXImately 10 billion years, while a star ten times as massive would only last around 20 million years.•
Anuclear fusion process that fuels stars with core temperatures less than IS million Kelvin, proton· proton fusion Is a common reaction, It entails two protons fusing, with one being transmuted to a neutron. forming deuterium. The deuterium then fuses with another proton, generating a helium nuclei, two of which then fuse to generate an alpha particle and the release of two protons.
+ ill
Proton·proton
•
+
Carbon fusion For StiUS with central temperatures over lS million Kelvin, carbon fusion tends to be the dominant process, It reVQlves around adding protons to carbon
Helium fusion If the core temperature of a star exceeds 100 million Kelvin, as is typical of red supergiant stars, then helium·helium can become the dominant reaction. This Involves two helium nucleuses fusing to create beryllium·S and emilting gamma rays, before the beryllium·S fuses with another helium nucleus and generates carbon·12, which unlike beryllium is stable. Helium nucleus
+-
+ '. • N N) 'NN. +
+
115
Sights of the Universe many collISions along with radioactive milterial ifs accreted heal everylhlng to melting pomt. As a melled mass. the
planetesimal's SUUClUIl!' GIn reform. In a procl5S called dlfferentlillJOl\, me fa're of gravily c:oncenmlle5 the mell:ed metals into dn mner COle, sunounded by an OU!el' crust of
lighter rocky 5ihcate:s.. The result IS a pIOOlpIanet an ~erad·hke mass with dIStinct LJyt'fS. CM!r 1I1nl!, gravity evens 01.11 the pnxopIanefs shape. formu18 II mID .. sphere A tem5l.nal plane!: mighl form an atnlOSlllE.t Ia)w through olltgasSIIlg. Essentially. heat from the planet'S mteoor C
0I1so a prease ba1.lnce of planetary size imd proximity 10 the central loW. When;1 sm.Jlll!t planet OfbIlS very dose to il slar, hke Mercury. the sun's he,)! b!.lsls aw,)y any atmosphere, leaving a oorren rocl Meanwhile.. a planet like Mars IS so far from the Sun that aJ11ts waler Is locked up In ice. But Just a hI! further 10, you gel Earth - a planet [mrS the right size and in 1M nght positIOn to form a robust atmosphere that could support nfe. While there is gencral agreemcnt among astronomcrs that terrestrial planets formed along these lines, the origins of Jovl.iln gas giJnt planets, like Jupiter and Saturn. arc less certain. One possibility Is they start out the Sdlfl(' basic way as terrestrial plancts. steadily accreung solid mailer to form a massive protoplanct. If it grows large cnoogh aboul15 umes the slzc of Eanh such a protoplallCl e~ts a strong enough gravitational poU to capture hydrogen and hehum gas In the propIyd. The gaseous mass then sweeps up rT'IOle maleri.ll growing Into a Jov1an behemoth.. Thefe Is a relauvcly small supply of heavy metals and siliCate in a proplyd. makU\g It unhkely tNt a prOloplanel: coukl accumulate CTlOIJ&h metal and rocky lTIdlenalto reach the SIZE' necessary 10 hokI on 10 hyd~ and hebum gas. InsteacllhlS modcI says. the iniual planeury core of a JovIan pI.met forms WI cJ ftozen hydrogen tnllpoo.nds. such as methane. ammoma and Woller Neal Iht ('l,'flt~ cJ a proplyd. the deveIoptns proiOSlilr makes I tOO hot: for hydrosen
118
Sights of the Universe compounds to condense into frozen solids. They remain in g.J.SE'OUS form and so do not accrete to developing planC'teslmals. But if you mow lar
enough away from the hot prolostar. past what's called the froslline. the temperature drops low enough that hydrogen compounds can freeU'. With a much more abundant supply of solid material. large icy protoplallets can form and capl:ure the swirling hydrogen alld heliu m gas.
The organisation of our Solal System supports this theory. The
inner planets, Mercury, Venus, Earth and Mars are all relatively small and rocky, suggesting forming glam icy or gaseous planets wasn't possible close to the Sun. whIle the outer planets, Jupiter. Saturn, Uranus and Neptune,
are much larger. The chief argument against the
accretion model for Jovian planets is timing. In well-supported models of
solar system evolution, there sImply isn't enough lime to grow lhe massive icy cores before Ihe developing solar system loses the bulk of its hydrogen and helium gas supply. While the lighter gases are the dominanl material dunng the proplyd's early lile, their days are numbered. In the case of our own Solar System, some 10 million years afler the Sun first formed as a protoslal, the energy of nuclear fusion reactions likely produced powerful solal wrnds that would have cleared out the remarning gas in the proplyd. That's a tight wmdow fOl Jovian gas giants to form. And neighbouring stars may lead to the window shrinking even furl her. Asuonomers believe that stars generally form In c!uslefS thaI conlain massive, hot slars. Calculations say radiation from these stars would accelelate the evapofdtion of gaseous material in nearby proplyds. shrinking the period of plentiful hydrogen and helium to betwC{'n 100,000 and 1 million years, Thai doesn'l appeal to
be enough time for a Jovian gas giant to form through the accretion model, yet observJnons of distilnt soIJr systems show that tht'SC gJs giants are very common, An alternative theory, known as the gas collapse model. presents a fasler formation scenalio. According to Ihis model. gas giilnts form dirC1:tly from the swirling hydrogen aocl helium in iI developing proplyd, As the matertal revolves around the pro!oslar, turbulence In the diSC distributes II unevenly. ThIS unevenness forms kT10ls of dense gas. When enough gas is concentrated tightly eoough, its dense mass causes it to collapse in on ilself, fonning a gIant gas baU. To put il another way, the gas giant is like a failed star, It forms the same basic way as the protestJr, but doesn't have sufficient mass and energy for a nuclear fusion reaction,
The embryonic planet's gravUational pull takes over from there, sweeping up massive amounts of gas, as well as any solids in the vicinily, quickly adding to us bulk. Collet'ted iet' and metals condense althe planel's et'ntre. forming a solid cote after Ihe gas has acromulated, rather than before. The whole process might happen as quickly as a lew hundred years, Observations of Jovian exoplanets (planets located outside OUI Solar System) have given some credenet' to Ihis model- or at least challenged Ihe Jovian accretion model In the wave of exoplanet dISCOVeries over the past 25 years, one of the biggest sutprises has bl>en the so·called 'hot Jupiters', Jovian gas giants that orbit very close to their suns. Tht'SC planets would seem to conttadictthe notion that gas giants only lorm beyoocl the frost line. Ilowever, they may have formed
further ou~ but then migrated towards their suns. Aho5t of exoplanet dlSCovenes have given astronomers a much bigger picture 01 the tilflge 01 possible planets, which has yielded new clues about how planets mlghtlorm, But examlmng the end results can only tell them so much, Fortunately, we're likely entering a IWW era of diTect proplyd observation, thanks to advances In telescopic technology. The new Atacama Large Millimeter! submi1limeter Array (ALMA) radio tclescope in Chile, which should be fully operational III March, has already yielded unprecedented Images of planet formation in progress. As new disoovefles follow. astronomets expect to fill in morc piCl:es of the puzzle, taking us ever closer to undelstanding how our planet. and by extension all of us, came to be.•
Types of planets Terrestrial
Gas giant
Dwarf planet
Terrestrial planets like Earth and Mars are rocky planets with metal cores and high densities. They are smaller than gas giants and have slower rotation periods. In addition, their smaller size means they are less likely to have moons.
At a further distance from their orbiting star, gas giants are able to accrete more matter In their formation, giving them a large size and mass. For example, Jupiter is 11 times larger than Earth, and has a volume 1.300 times greater.
Smaller than a true planet. the difference between an asteroid and a dwarf planet comes down to its shape. To be a dwarf planet. a body must have sufflcient mass to achieve hydrostatic equilibrium, when it will become spherical.
120
What are asteroids made of? Protecting Earth is one of the main reasons why scientists keep a close ~ on asteroids, which are space rocks of all shapes and sizes that can be found scattered throughout the Solar System. Irs unclear how meteoroids, the rocks that become meteors when they crash Into Earth's atmosphere, were generated from asteroids. Still. NASA isn't ruling a link out and is examining asteroids to learn more about how the Solar System was formed. Since planetary scientIsts believe planets gradually grew from rocks crashing mto each other, the asteroid belt between Mars and Jupiter could be made up of the leftovers of the early Solar System. Therefore, ferreting out the secrets of asteroids could also give scientists clues dS to how the Solar System came to be. Possibly, it could even reveal how the Earth was born. Studying asteroids is a challenge for scientists, however, because they are so small. A typical space rock is perhaps just a few metres across. However, the largest known asteroid in our Solar System, Ceres, is 950 kilometres (590 miles) in diameter and makes up a third of the mass of the known asteroid bell. However, through a telescope sitting on Earth. an asteroid of this siT.!' looks Incredibly small. This makes asteroids difflcult to see and study, but sdenlists are prclly cralty when it comes to gelling information from a distance. Most asteroids, according to NASA. can be classified in three groups: C-type (carbonaceous), S-type (siliceous) and X-type (VdriOUS compositions). Around 75 per cent are C-type asteroids that lurk In Ihe outer asteroid belt. They all' very dark and probably lack helium. hydrogen and other lighter
"In 1995, there were only 335 known near-Earth asteroids, however, today there are more than 9,700 catalogued"
Explaining the elements
~~
....
..(=-------;;;;;. Titanium
This element could come in useful for building lightweight alloys for use in spacecraft
..'-",,-.-t. Magnesium A very common element In the universe. it Is used In fertilisers aod to make magnesiumaluminium alloys
• Samarium This element. which is rare on Vestd. is used on Earth for industrial magnets. cancerfighting drugs and nuclear reilCtors
Ag - Silver AI - Aluminium B - Boron Bi - Bismuth C- Carbon Cd -Cadmium
CI - Chlorine Mn - Manganese 0- Oxygen P - Phosphorus Pb -lead Pr-Praseodymium
S - Sulphur Sb - Antimony Sc - Scandium Si - Silicon Th - Thorium Tm - Thulium
U - Uranium
• Manganese An important element for stainless steel
Ba - Barium Co - Cobalt d - Chlorine Eu - Europium Fe - Iron Mg - Magnesium
Mn - Manganese Na - Sodium Rb - Rubidium Sc - Scandium Si - Silicon Sm - Samarium
Sr - Strontium Th - Thorium Ti - Titanium U - Uranium Y - Yttrium Zr - Zirconium
123
'volatile' elements, S-type asteroids, aboutl7 per cent of the population, make up most of the inner belt rocks in the asteroid belt. They're a little more renective and are usually made 01 metallic iron mixed with silicates of iron and magnesium. Squeezed in between these asteroids are X·types, whICh are mostly made up of metallic iron asteroids and the like. These are found in the middle of the asteroid belt. While most asteroids sit safely between Mars and Jupiter, some appfOdch Earth and sometimes cross its orbit. Scientists think most of these asteroids were 'dlStUIbE'd' into different orbits due to Jupitel's gravity or collisions with other asteroids. There are three types of near·Eanh asteroids. Amors cross the olbit of Mars. but don't get very close to E.lIth. Apollos cross Earth's orbit in a peliod of one year or longer, while Atens also cross the orbit but in a shorter time frame - a year or less. In the past two decades, space agendes and observatories around the world have discovered thousands of these types of asteroids. In 1995, there were only ]]5 known neal·Earth asteloids, however. today there are more than 9,700 catalogued. according to NASA. Since scientists believe we have now found more Ihan 90 per cent of threatening astCToids that are more than one kilomt'lre (0.6 miles) in diameter, NASA is now emphasising the search for finding near·Earth objects of 140 metres (460 feet) or greater. Still a much smaller object can cause a lot of damage. The dinosaurs were probably wiped out by a small body just ten kilometres (6.2 miles) in diameter that hit the Mexico area about 66 million years ago. In Russia this yeal, more than 1.000 people were injured when a house·sized asteroid - 17 metres wide (56 feet) - detonated in the atmosphere. The cvent caught both the public and astronomers by surprise, demonstrating we still have a lotto learn about predicting meteor strikes on Earth. In more recent years, several space missions have ventured out to asteroids to get more information from closeup. NASA's Dawn mission, for example, scooted by the asteroid Vesta In 2011 and IS flOW en route to Ceres. Its closeup views rcvealed a battered world that. surprisingly, has some links to how the Moon was
124
formed. Vesta and the Moon were each peppered by a population of space rocks ejected into the inner Solal System early in the Earth's history. Both Jupiter and Saturn shifted their orbits in less than a million years. Theil motions perturbed the asteroid belt and sent the rocks into planet·crashing orbits. This bombaldment had been known about lor decades - astronauts on the Apollo missions even discovered evidence of II on the Moon - but
What lies inside Asteroid Vesta. - - - - - - , Vesta, the second· most·massive aSleroid in the Solar System, stands in a class of its own called V·type asteroids. They tend to contain more pyroxene than S·type asteroids
• Crust of Vesta Vesta melted at some point early in its history, producing a 'differentialed' core and a basaltic crust
scientists didn't know until recently that Vesta had also experienced it. The next step will be obtaining a sample of an asteroid and studying it here on Earth. Origins Spectral Interpretation Resource Identification Security Regollth Explorer (OSIRIS-REx) will journey into space in 2016, scoop up a bit of din from the Apollo asteroid (l0l955) 1999 RQ]6, and return it to Earth by 202] for further investigation.
, - - - - - - - - - - - . Core Data from the Dawn mission showed that Vesta has iI core of 110km (68ml) in radius. The core Is mostly made up of iron
• Mantle Vesta's mantle, wedged between the core and crust. likely includes olivine and diogenite
ICS & SPACE ADMIN/S1
Launchmg stuff into spaa' IS ~n inherently messy business. You end up le~vmg behind sc~lleled rocket structures. fuel. nuts. bolts ~nd othN miscellaneous equipment. PIeces fall away. collisions turn bigger pieces into m~ny sm~Uer plea'S. and unspent propellants cause jettisoned rocket structures to explode. In the Sixties, the US even dumped 480 million pieces of copper wire into OIbit in an effort to create an aruflclal meteor (fail that would reflect Tadio signals. All olthis poses a realthr{'at to the International Space Station (155), active satellites and. to a far lesser extent. all of us on the ground. Even very small pieces, such as tiny chips of metal or paint. can wreak considerabk> damage. Space debris in low Earth orbit (LEO) typically travels at about sev{'n to {'jgtll kilometres per second (4.3-4.9 miles per second), about seven times fast{'r than a rifle bullet. A collision with a one·centlmetre (OA·inch) object at that speed Is the equivak>nt of bE'!ng hit by a bowhng ball travellmg about 480 kilometres per hour (298 miles per hour), Sueh an imp.u:1 could smgle· handedly destroy a satellite, F'ortunately. most of the junk poses no physical threat to us on E3rth. Almospheric friction easily vaporises smaller debris. On average. Olll' PI~ of lTacked space debriS dIps mto our Jtmosphere every day, and the vast majority of il never makes ilto the Earth's surface. Larger piect'S, such as intacl rocket structures. can make it through without burning up completely, but tlK> odds are It WIll end
up in the ocean. which covers 7\ per cent of the EdTth'S surface. In th{' {'atly days of space exploration, orbital debris wasn't a big concem. But once the risks of space debris becam{' clear, agencies started to address m{' problem. "NASA pioneered mitigation procedures for minimISing c\{'bris: says Eugene Stansbery, program manager of th{' NASA Orbital Debris Program Office, "Now, many space agencies hav{' adopted mitigation standards or r{'(]lllrem{'nts, There is also a set of United Nations Space Debris Mitigation Guidelines (that) c\{'al with mimmising debris during routine operations. limiting tl\{' potential for collisions by reducing the lifetim{' spent In crowdro orbits, reducing the risk of explosion by ehmlnating stored {'nergy at end·of·operationallife, and limiting risk to humans on the ground from re·{'mering satellltes: Akey strategy Is to ensur{' upper· stage rockets end up at a lower'altitude OIbil.leading them to dIp into the
Earth's aunosphere more qUICkly, Debns left at altitudes below 600 kilometres (372 mIles) will burn up withm about thrre to four years, Debris left al 800 kilometres (497 mIles) may be in oTbitlor decades. Any debris above 1.000 kilometres (621 mtles) wtlilake a century or more to Teach II\{' atmosphere, Today, Stansbery explains, all we can do is keep track of the most dangerous debris in orba so we can stay clear of it: "In the US, thC' Department of Defense (DoD) operates the Space Survelflance Network (SSNj, which consists of a worldwide network of radar and optical sensors. 1Ilclud1llg one space·based sensor, WhICh tracks satefhtes, includmg orbital debris. ThIS network is controlled and tasked by the loint Space Operations Center (JSpOC) located at Vandenberg Air F'orce Base, 10 Calilorma: The network is eqUipped to observe debris in low Earth orbit (LEO) as well as geosynchronous orbit (GEOj, "Norm,dly lilct.Jrs are used 10 track
low Earth orbital debris: Stansbery ",lnd optical reJcscopes are used for geosynchronous debris. Optical telescopes provide 'angles· only' data whereas radar typically provides an addillonal measure of the range to the debris, Perturbations to the orbits are also different for the two regimes. Therefore, the algorithms and software used to determine and maintain the orbits are different for the tWO regimes: KeepingsateJlites and spacecraft safe depends on precisely charting the debriS' path in relation to aJithe operational obje<:ts In orbit. "A series of observations is taken on an objectl.'ither by radar or by optical telescope: StansbE'ry says. "An mitial orbit is estimated from these observations. That orbit IS then propagated forward in time 10 prediCt its location when it is in view of other sensors. These sensors will look for the ob}ect and use its posinon to refine the orbit. DnC<.' the orbit [of the object! is sufficiently determined, sensors are e~pliljns,
129
Sights of the Universe then routmely Llsked to upddte the object's orbit as needed: Irs I'lOI possible (() lfack ..11 debns. SW1sbefy says: 'The pmnary obsI:acle
to IrackIng debns IS the small SIze ollhl> debns. Radars and opl:k.ll
teJesmpes are limited by then sensrtlVUY In low I::.tnh OfbIL the' SSN can only detect debns bigger lhotn flYt' lC len cenlimeues (two 10 lour inc!ll'sl efferuve diameter At geosynchronous ahlludes, It only deltas debns Lu8£'f than about one metre (12 ffft) diameler. These 5IteS are a small fracllOll of the orbaaJ debns 1M un damagr a typICal sp.iICKlafL" Slambery says compwm are key to avoiding collisions: "T'he JSpOC runs a softw~ product thaI predlC!S close ~ between actIVe s.nelbU5 and ot~ OIbdal ob,tcts.lf a close dpJlR)iICh is predicted. the JSpOC will ~
an Otbral Conjuncllon Message
(OCM). whICh has the
muons 0100
WlceH,unll('S In Iocauon lor the conjuoctmg obtects. An opet'aror un then dC'lennine what aetl()l'ls, such as moving the SilteUlte. are prudent: The lop pnonly IS aVOldmg catastrophic collisions with manned spacecraft, such as the ISS. "For the ISS and relatC'd spacecraft,
there IS a group ilt Johnson 5p.lce Center tnat receives the OCM: Stansbery says. "This group takes the orbit and orbit uncemllntics and calculates a probability or collisIOn. Based on this probabIlity, there ale nIght ruk's that dictate what must be done when certain probabl1lty thlcsholds all' l'xceeded. Thl' action would normally be a maOOl'Uvre givl'n l'Ilough time. Tlml' is fll'('(je(\ to pla.n alld {')ll'CUtc a maTlOl'Uvre.
Dunng the buiklup to a mallOE'Uvre, the tca.m momtors any addnional triKking mlormauon lrom JSpOC and can ul1Cl'l the manoeuvre II later data lf1Chcales a reduced nsk.' On avt"rJ;ge. the ISS has to ITIlM' out of the way of tracked debris tWICt' ~ year, about double the frequency of several years ago. There isn't always ttl1"le' to ITIlM' dear of the debns. "'Someomes. the warnmg of a
con;...ncoon does IJO( come soon enough to safely pian and execute a IThlr'lOl."UVre: Stansbery says. "ThIS has ~lly
resulted in whal15 termed 'sale I'w\'~rl where the ISS crew Will ITIlM' to the!.r Soyuz return capsule umilthe COf\JUncoon has passed: In the event of a ooIllSlOrl space JUnk trackers suddenly have a hosl of new debns to catalogue. 'NASA's OrbIlal Debns Program Office performs several tasks: Stansbery says. "Fim. 'Nt' uSt" a software package that takes the information on the time, location, and masses of the ob;ects and calculates near and mid-term risk: toaher spacemh. ffiOS( lJO(abIy. the Iss. These risk: esumates tell the crew if they shoukltake action. Then. NASA begins to ooI\e(t as much data 00 the coIhsion as it can in order to characterise the colliSIOn bett('r and evalwte Iong·term damage to the environment: Stansbery says the Space Surveillance NetWOik has some upgrades on the horizon: 'There are a couple of new 5ellSOrs thill promise ImprO\'ed senSItIvity. DoD Is plannmg a new 'Space Fence' phased array radal that will be able to detect and lI3Ck debris as small ilS tWO cenumeues (0,8 inches) elfectlve d~meteT at
The 'Space Fence' mission control will track pieces 01 space junk that are in orbit alOUnd the Ea.rth
The AN{FI'S'SS radar in Florida is one of 29 sensors in the Sp.ace Surveillance Network (SSN) space station altitudes, The DoD is also testing the Spdce SUlvt'l1\ance Telescope (SSI') which will Improve sensillvity fOl geosynchronous OIblts.· Up until recently, the biggest SOUlce of indIVidual debris plcces was rocket explosions, In its early days, NASA routinely let upper-stage rockets enter orbit with unspent fuel. leadlllg them to blow up, scattering bits of shrapnel Into orbit. In the Ddst six years, two unfortundte events put satellite PieceS at the top of the debris list First, in 2007, Chind tested Its anti· satellite capabilities by destroying one of its own weather satellites with a missile, The explosion created more than 1'iO,OOO pieces of sp.ace debris, making it the WOlSt Sp..lCe junk event m history. Then, in 2009, an accidental collision ooween a defunct Russian mJHtdty satellite and a US communications satellite added mon." than 2,000 additional pieces. These colUsions illustrate
The Kiernan Reemry Measurement Sire (KREMS).a US lacilityon Kwajalein Atoll in the Pac:ificOcean. includes foor one-of-.a·kind radar systems that play integJal roles in the Space Surveillance NefWOrk (SSN)
01 dcbris can creatc thouSdnds of smaller pieces of debris. which can then collide wIth other debris. cleaung thousands of new pieces. Destroymg lust one large satellite could double, or poSSibly Lriple the amount of debris in low Earth orbiL Today, Kessler has a clear Vision 01 the course we're on; 'Unless some country or OIganisation 5lgnitkdntJy increases the rate that ob)l"Cts art' hemg placed mto the vanous regions 01 Eanh Orbit. the rat!.' of debrIS growth is fairly predictable: one can expect il 10 slowly increase in reglons of F.•mh OIbit below 2.000 kilomelTes [1.240 ml!<'5) (l.EO), regardless 01 what actions iIIe raken to rry ro prevent that growth, as .I result of random collisions involving large, intact objects," Kessler prediClS re<:hnology will have ro evolve to keep up wilh rhe increased junk: 'Ovt'J the next 100 years, we (an expect to see .I slow increase in lhe ratc of sp.Jcecraft failult's due 10 an increasing number 01 hyperve1OC1ty ImpaClS of small debris fragmcnrs resulting from these collisions. Sp.acecraft operarors will slowly realise rhey need to i1dd shielding to crItical componentS, increaSing rhe weight of their sp.Jcecralt even though the added weight will be undesirable, ahhough It will be manageable for many de<:ades: The rdle of milJOr colhsions will increase 100, he says: "During this time, we can expect about one catilsllopJUC,
debris-producing collision ('\Iery t('n years: there would be linle possibility that we'd notice any 'colliSIOnal cascadmg' unril perhaps nea.r lhe eoo of the renlury, when the frequency of calastrophicro11iSlOns would become mOle frequent, dependmg on the success of previous actions to slow the growth In the debris populahon that are already in place (eg minimising tho:' posSiblllly of explosions In orbit and requiring new spacecraft ro be OUI of orbit within 25 years at the end of their operational hfe)" Because we're beyond lhe polOt where more conscientious launches will ev('ntually solve rh(' problem, we'll end up locking ourselves in with a wall of rubbish il we don't start cleaning up after ourselves, Kessler sees an Immedklte need lor action: 'Without the begmning of mOle aggressive actions wllhin the neXilew decades to reduce the curlt'nr populauon of large intact oblects 1Il LEO, the glOwth in the debris will acrelerat('. and not stop Increasmg for hundreds, if not thousands, of years. making LEO too hazardous an environment for any spacecraft to operate lor any slgnlf[cantlength of time befOle it will become another source of del:Jns." Things might also progress mOle quickly, Kessler sa~ "ThIS scenario could become much worse if some entity were to place a large constellation. consisting of thousands
"The primary obstacle to tracking debns is the small size of the debris. Radars and optical telescol?es are limited by their sensitivity' _
Collisions
and near misses FebnJary 2009
The first man·made satellite collision A560kg satelille operated by the US company Iridium was just one month away from retirement when II smashed into a 950kg Russian Kosmos military ~tellite. The collision added more than 2,000 pieces of debris to Earth orbit.
January 1997 It's raining junk An Oklahoma woman on a Jatenight stroll saw a streak of light in the sky and then felt something brush her shoulder - a piece of metal from a us Delta II rocket launched in 1996. The same night, a 260kg steel fuel tank narrowly missed an occupied farmhouse.
January 1978 Radioactive landing When the SoViets lost control of the;r surveillance satellite Kosmos 954, its erratic orbit took it back to Earth, spreading debris over (anada's Northwest Territories, The (dnadian and US military initiated a 124,OOOkm' search for radiQdctive material from the satellite,
June20n Buzzing the International Space Station With only 15 hours notice, the ISS crew didn't have time to move clear of a piece of junk hurtling towards them, The 1in 360 chance of impact sent the crew to their SoyUl sPilce capsules, ready to undock and escape to Earth, but thankfully, the object missed by 260m,
stansbery. program lIW1i1ller of the NASA 0IbIW Debris ProgIam 0fIIce 131
Sights of the Universe of satellites in LEO, as was proposed for our 'Star Wars' defence programme
in the Eighties. J lopefully, we ,ne wise enough today to avoid that. There is also a possibility that the natural orbital decay rate 01 satellites in LEO will decrease if we should experience the kind of low sunspot acUvity as
was observed In the late 17th Century, thinning the upper atmosphere and increasing the need to physically remove more satellites from orbit."
The first order of business is planning ahead with Ill'W objects we put into orbit going forward "There are two other popular
regions of Earth orbital space: Kessler says. 'Mid Earth orbit (MEG),
where CPS satellites arE' located, dnd gt'OSynchronous orbit (CEO). when.. satellite TV transmitters are located. Both wlll suffer the same late (as LEm but over a longer time period. We
could avoid this fate in CEO if there is widesprrod agreement to place objects
in an inclined mba that significantly reduces comsion velocities betW('Cn uncontrolled satellites_ If adopted, such an orbit also has the advanlage of saving station-keeping fuel for spacecraft operators, Objects in both LEO and MEO must bcon paths that cover large areas of the Earth's surface In order to meet their operational goals. Consequently, the only solution to the orbital debris issue In those regions IS to not leave objects In orbit after they've fulfilled their operational roles. Asmall, pre-planned, propulSion capability is sulfiaent to remove objects from LEO, and many futUle payloads and upper-stage rockets are planned 10 have this capability: The big questton now, however, is how to deal with all the debris that's already In orbit. "There have been a number 01 proposals for removing existing
"One option being looked into by scientists in a bid to remove space debris from orbit is to target the junk WIth a ground-based laser" debris: Stansbery says. "At present no system that is both technologically matUlI.' and economically feaslbll.' has bl.'en proposed, 1I0wevl.'r, the United Statl'S and other countries are pursuing research and dE'Vl"lopment of technologies and techniques to remove in-orbit debris." Stansbery E.'xplains thl.' challenge is twofold: "It Is really a combination of physics and economics. The classical way of removing large satE.'llltes from orbit is to rendezvous with the ooJ€'Ct, matching velocities so that the E.'ncounter doesn't result m a collision. Then you attach to the satellite and
Lost in space
Tool bag
Glove
Spatu~
Astronaut Heide Stefanyshyn-Plper lost a 14kg tool bag on an ISS spacewalk In November 2008. which could be seen in orbit from Earth.
Astronaut Ed White lost a glove on the Gemini 4 mission in 1965 during the first-ever Amerign spacewalk. It stayed in orb~ for a month.
Space Shuttle astronaut Piers Sellers lost a spatula on a spacewalk In July 2006 while spreading material on the shuttle's heat shields,
132
move illO eilher a graveyard orbil or cause the satellile to re-enlerlhe Earth·s atmosphere wilhout unduE.' hazard 10 people on the ground This is a very energy·intensiV(' scenario. Also, economically, removing one large satellill.' can be very expensive when launch costs and operations are considered. The removal of one, or a handful. of large satelliles, does nOI Significantly reduce Ihe risk. Many, many satelliles need to be removed via a Iong·term, sustamed effort: In the face of Ihese obstacles, scientists have been lookmg into alternative measures. One option is
10 target deblis With a ground-based laser, ThE.' laser would heat the df>bris jusl enough 10 produce a small plasma jet. which would act as a rockf>1 10 slow the debris down so that It falls into Earth atmospherf>. Boeing is exploring a rocket design that would release aboullf>n tons of inert cryogenic gas, such as xenon or kryplon, into a debris-heavy areas. In the seconds before It dISSipated, the cloud of gas would theorf>lically slow the debris enough for It 10 fall OUI of orbit. ThaI'S right Ihf> solution to cleamng up space junk might just be launching more junk inlO space.•
OrbIting functIonal satellites. Orbrtlng dysftlflctlonal satellites. ~
Orbllmg space Junk "f> IOcm d,ameter
Sights of the Universe
How we see the The ESA:s Gaia spacecraft is set to bring us new discoveries Over the last few decades we've seen a vartety of Ial"g{' and amazing telescopes. From the Hubble Space Telescope to the Herschel Space Observatory. we've been able to observe our Solar System, the Milky Way and even the universe in unprecedented detail. Now, the ESA wants to attempt something new. Using the revolutionary Gaia spacecraft. it will track the motion and position of 1% of the 100 billion stars In OUT own galaxy. Irs a daunting prospect but one thaI could provide us with a fresh new insight into the formation and structure of the Milky Way, and also
gle.m new information about asteroids. exoplanets and our Solar System. The Gaia spacecraft will ny the largest camera ever with a total 01 about 1,000 mIllion pixels. This revolutionary pil'Cl' of equipment will
be performing wide-angle astrometry - the science of delennining the 1X)S1tion of ob}ects in the sky - to complete its five·year mission. Until
now. astrometry has largely bct'n confined to Earth, and It has lx>cn difficult. The Sun and the Moon aft' both a nUisance for Earth·based astrometry. which IS what makes Gaia so Important This spacecraft won't be placed in orbil around Earth, but flown OUI to the Sun·Earth L.agrangc Point 2, a position i5 mIllion kilometrcs (930.000 milcs) away in line wIth the Earth and Sun that provides a shielded view of the entire cosmos. ·An the 'bad things'. the Sun, the Earth and the Moon. are roughly in the same dirl'Ction" says Gaia Pro}cct Scientist Timo Prusti. "So if you shield that 'bad,' dirl'Ction, then you are free to look the other side:
The 1.2 position wUl enable Gaia to use its incredible camera to make the largest and most precise three· dimension map of our galaxy. Every star it observes will be acrurately measured to determine its motion around the centre of the galaxy. Most stars gained their motion from the birth of the MHky Way so, by studying this, Gaia will enable astronomers to peer back in the history olthe galaxy. Gaia will observe each of its one billion stars about 100 times Gaia is also expected to make other discoveries. It "wlll also address questions concerning our own Solar System, extra galactic ob)eCts (some half a million quasars will be observed and several million galaxles~ stellar astrophysics (by providing the distances to ob}ects) and general relativity: explains Prusti. Gaia will also ·provlde several thousand new
planets, but the strength is in the area 01 Jupiter·like planets in five to ten year periods around their stars: The spacecraft itself is composed 01 three main components tOTaling about two tons in launch mass. The first is the payload module, which provIdes support and eJl'CIronics for lhe camera and also processes the raw data. The mCl:hankal service module houses mCl:hanical. structural and thermal elements that support the camera and Ihe spacecraft·s electronics. Finally the ell'Ctrical service module manages the dala and provides communicatIOn with Earth, amongst other tasks. Gaia's camera isn't IJke a traditional camera, though. 'Gaia will provide roughly the same spatial prt'Cision as Hubble, but for tlK> whole sky: explaIns Prusti. ·However, Gaia is only doing point sources. So you will not get the prelly pICtures Hubble IS providing. Gaia provides an all sky map with high precision positions and movements of objects· Gaia is eXpl'Cted to launch in August 2013 atop a Soyuz rocket. While its initial mIssion will last untll 2018, it could be extended. "Hardware and propellant is seoped nominally for a one year extension: SilyS Prusti, ·and clearly if everything works it is 00 problem to find a seience Cilse lO support applications for further eKtensions: However long il lasts. you can be sure that Gala's mission will provide some groundbreaking SClenrific discoveries that wHl increase our undersranding of the Milky Way and its resident objects.. l11e learn from Astriurn gather
II
round lhe supper! panel
,IISTRIUH
..
• .,
\
",-.,M",.
"
;.
,
he energy of
a billion suns
_ _Inlllllto...Deep Space When we it vanes from Slat to star, eventually a star's source of flK'l runs out In most cases the predominant ek:'fTlent left at the star's rorl.' Is non, which no st<1r IS <1ble to fUS(' Wh.lt Mppens next is sImply astoundmg. Eventually, so much iron WIll bl.uld up that the st<1r can no longer support its own Weight Until this point, and indeed for the majonty of <1 st<1r's mel1ml.'. the force of gravity pulling the st
140
collapse supernovas. The former typically occur in stars w~ their mass exceeds 14 solar masses. known as the Olandrasekhar llffill. due 10 the acc:mion of IlliIller In a binary star system wllh a white dwarf star, while the latter Involve the collapse of stars between eighI: and IS solar masses. Both types are further sub
"" ,'""""""-
One of the few supemovas to be obser....ed was SN 2OO8D m the spraI galaxy NGC 1770 back in early 2008. By chance. It'St'archC'fs usmg NASA's orbIUng Swift teIesrope noIiced an Increase In X-~ from the star, and ImmedlOltely alerted ~ olher ground and spac'I.' lelescopes to the ~nl The resultmg blast lasted JUSl five mInuteS, but the research will surely last a ltfl.'l:ime. The expanSlOl'l rail' was estlmolled at IO,O(X) kiJometres (6,000 miJes) per second. allhough one side of the star expanded faster than the othC'r, suggestIng th.lt the expbsion was oCkefllred. The U01\11.'tSe IS abundanl Ln hydrosen and helium but noI so much in hC'avll.'f elements such as carbon and oxygen, hfe-esscntlOll elements Without which planets lilte Earth roulcl not be<:orrte h.lbltable. The only place where these heavier elements are known to be made is m the' Yery hean of stars. where they arC' stored unul the star e~pJodes as a supernova and scatters them Into the surroundmg space. Without supernovas, IhC'Se elements would remam locked away, unable to contribute to the formation of mC'LlI-rich obj(-'Cts like planets and asteroids, It's "Vf!ry likely thai planetary systems. like our own Solar System, were born 10 this way, from a cloud of dUSt and gas left behind after a stJr went supernova, Another important consequence of supernovas IS the formation of new stars. One of the oldest stalS
Into Deep Space
--
lila! we know of is HE IS23-090L a. red gWnl sur 7.500 light years from Eanh. It was thought to have formed about 132 bl1ban years ago. 500 million yeal5 alter the estUTlaled begmmng dille univefse Clearly (hIS means thai mosI SlaI5 thal we know ol were formed aller the BIg Bang. In some cases
as our own Sun) many bl1bons of ye.ars alief TIle only wiI'f new stars couki have been born was II oIc:\e£ stars lhal survived from the b1nh oIlhe universe e'o'efltually weOl supemcwa, releaSing thelr various elements and eventually k>admg the way 10 the
formation fA new stars. The fiMl major contribution of supernovas to rhe universe Is the continued addition of heavy elementS
to the interstellar medium. The gradual growth In abundance of these heavier elements. ones thaI were only found in tfaces before, has had ,:In odd effect
on some SIJl5. Those like our own Sun undergo a somewhat different fusion process to those SEars born nearer the stan of the universe. as the former all' moder-lied Il'IO«' by the presence of carbon. IllS likely that fmure st.1!S will corninue to be altered by the presence of more heavy elements. funher allemtg the fusion pmcess: Wllhm stars. So. 11"5 safe 10 QIj that supemavas are really quite importalll. bU! how do we know so mu:::h .lbout them? Aller all _\'to only observed very few. mstead normally CiltChing only the aftermath or the resultant f1.'fT1I\oUW.. Well fortunately by obsefVIll8 the .tftenn.tth we're able to dlSCem a kJ( about the expklsut Itself. For roe thing, most Type la supemov.lS seem to undefBo very SImilar final moments. If we see one expkxie we are able to calculate how far iJWay It is thanks to SOITlething known.lS the "standard candle" ITlClhod. where all Type la explosions expk:de with pretty much the same magnitude. In addition. using spectroscopy, we
ca.n analyse the resultant remnant and. by observing its SIze and composition. we can work OUt what the original star might have been hke. Supernovas will continue to be one 01 the most fascinating and exhilarating events in the universe. provlchng us with iI view into stellilr formation and the death of stilTS. It is thanks to these events that we know 50 much ilbout the mner compositlOO ol stilts. ilOO by COrtllnuing to study them we Will uncilrth mcxe secrets ol the umverse..
Wbat is a remnant? supemovil remnant is the expilnSlOll oCthe blast wave from the supernova.lS II moves through sp.-.ce. pushing maten.ll out aioflg with it that we can observe- m dlfferefll wavelengths from Eanh.l11e expilnsklrl rate olil remnant can be up to severalthous.:tnd kilornetres pet second. approaching ~ the speed of light. and It may continue for hundreds or thouSilndS of years. Many nebulas we ciln see hom eilrth are the result of the eXpilnsion of supernova remnants, and they Ciln often meilsure several hundred light A
years across.
Most spectacular supernovas Crab Nebula Exploded: 7.500 years ago Distance: 6.500 light years This famous supernova remnant has a rapidly rotating star known as the Crab Pulsar at its centre. left behind after the original star exploded. This nebula is now 11 light years across but is stili expanding at a rate of 1.500 km (930 miles) per second. 0.5% the speed of light. It is part of the Perseus Arm of the Milky Way Galaxy and the nebula is also referred to as Messier 1 or Ml. being the first Messler Object catalogued in 1758. The explosion of the supernova that created this nebula. SN 1054, was recorded around the world In 1054 AD.
Kepler's Supernova Exploded: 24,000 years ago Distance: 20,000 light years
Observed by astronomer Johannes Kepler In October 1604. hence the name. Kepler's Supernova (SN 1604) is the most recent stellar explosioo that was visible to the naked eye on Earth. althoogh evidence exists for a Milky Way supernova whose signal would have reached earth around 1868. but was flOt visible to the unaided human eye. Kepler's Supernova was brighter in the night sky for three weeks than any other star or planet. except for the Sun and Venus. and could even be seen during the day.
RCW86 Exploded: 11.000 years ago Distaoce: 9.100 light years This supernova remnant is thought to be thaI left behilld after star SN 18S blew up in 18S AO. It was recorded by Chinese astrOflOmerS and remained visible for some eight weeks. Recent X·ray studies show a good match for this estimated age. As such. RCW 86 is the oldest recorded superflOva. and was thought to be a companion star supernova. The remnant Is bigger than scientists would expect from such a supernova. suggesting the initial dwarf star created a 'cavity' in space before it exploded into which ejected material could quickly traverse.
COming soon to a galaxy near you•..
IK Pegasi
Betelgeuse
Antares
Will explode: S million years from now Oistaoce: ISO light years IK Pegasi A is expected to evolve into a red giant. whic.h will traosfer matter to the smaller IK Pegasi e white dwarf star and cause it to explode In a Type la supernova. IK Pegasi is moving away. so while It is currently the closest star to us that can go superflOva. when it does in a few million years it will no longer be.
Will explode: 0 to 1million years from flOW Oistaoce: 640 light years Currently in the later stages of its life. it is expected to explode as a Type II supernova within the next million years. although it could explode at any minute. The star is a red supergiant and is less than ten million years old. a miniscule amount in astronomical terms. and thus it has passed through Its life rapidly.
Will explode: 0 to 1million years from now Oistaoce: SSO light years The red supergiant Antares has a companion star. Antares e, that Is thought will contribute to a Type 1a supernova event in the coming years. However. the exact timing of the supernova is unknown. Antares is more than 880 times bigger than our Sun ilnd thus the explosion is expected to be quite an event.
145
Cllifornia. Santa Cruz used 11 years or telescope observations at Keck to find Gliese 581 g, using a spectrometer that watched over its parent star. ThI'> spectrometer was used to measure the star's radial ve!oclty, or its movement relatlve to £.mh'sline of slghtlf a star has planets that are large enough and close enough, the planets tug at the star's gravity ever so slightly, With multiple planets orbiting the star, the star begins to WObble. Planet hunters have become so sophisticated in their techniques that they can take a star's wobble and lOfer how many planets arE' orblting it, as wen as the masses of those planets. ·Keck's Iong·term observations of the wobble of nearby stars enabled the de\l!'(tion of this multi·planetary system: stated Mario Perez, a programme scientist at the Keel: Observatory, in the news release collCl!'rning Planet G's discovery However, a team from Geneva (led by Francesco Pepe) analysed over six years 01 data concerning Gliese 581 using a spcctromttef atl.a Silla Telescope in Chile, Also in 2010.lhey announced at an exoplanet conference in Italy that they had not found any evidence of Glicse 581 g, That said, the preciSion of the instrument IS not sharp enough to definillvely rule Glicse 581 gout Subsequent wams of astronomers have been arguing back and forth for years now whether 581 g is actually there. or if the wobblc dctected around the star needs to have a new model made to explain 11. It wil1take more observations of the star before anyone can say for sure what lies withm that system and a definitive answer may not come fOl years 01 even decades. The planet 581 d lies slightly further from the star tnan 581 g. It's also.:l bit larger than our world.:lt bctw~n five and seven Earth masses, In a science paper posted on Arxlv, K.:IItencggefs team cans it.:l ·potcnti.:llly habitable rocky Super·Earth·, Also, Irs a little on rhe cold side when IT comes to habitabilitY, but some asrronomers believe a thick layer of carbon dioxide in the armosphere could shield 581 d from the cold, Of course. that's assuming the planet has .:In Earrh·like composiTion, which is not a guarantee. The theory. as Kahenegger explains it, is c.:lrbon dIOxide gets emitted from volcanoes on 581 d's surface. In the carty days of the planet's formation, r.:lin would wash the carbon dioliide OUt of the atmosphere so It couldn't accumulate. But as the planet cooled,
"It's the first time we've been able to peer across space and detect a possible planet that would be similar to our own" Usa Kaltenegger. asIIOphysIdst at Hatv3rd UnIvenlty that rain would tum imosnow. Snow doesn't have the same power to w.:lsh carbon dioxide away, so the gas would accumulate in the annosph<'re. 'It builds up in the atmosphere. Increases your greenhouse effcct. and warms umil you have water: Kaltencgger says. This makes it easier to believe that life would exist there. Even if planets 58\ g and 58\ d were vegetated, though, it would look a lot diffelent from Earth. The cool light from Gliese 581 would balely be enough for plants to phOTosyntheslse, 50 the plants would not be green like you would see here on Earth_ The colour would take tOO much energy, AdditIOnally, the light would look differem than what we are used to on Earth, as a red dwarf mostly gives off its enelgy 10 red light, In 20ll, Australian astrooomt'rs ~ who are involved In the search for extraterresttial Ufe ~ trained their cosmic ears at Glit>se 581. They linked togetller three radIO telescopes 1n Australia in an attempt to hear radiO signals coming from the system_
The asrronomels didn't hear anything. but that's not to say that hfe is absent Irom the system. Gliese 581 d and 581 g are both in or within tt\{> habitable zones, and it will take many years of lutme study to learn mOle about their climanccondiltons. In the meantime, Gliese 58l's system provides plenty fOf astlOoomers to study. There are up to SIX planets orbiting the star, each with.:l uni~ue envilOnment worth ClOseT study_ While 581 f and 581 g are oot universally accepted, there are lour others that are receiving further attention from astlonomers. 581 e is the closest to the star and would appear as a big Mercury il you well' standing on the surface. It's about double the mass of Earth. Next out is 581 b. which would be a gas planet - at 15.6 Earth masses - that is apPlOilching the size of Jupiter Third in the system, and befOle 581 g and 581 d, is 581 c. Planet C, more than five limes Earth's mass, ....,ouJd actually look a lot like Venus, in that any water would have evaporated from
the surface and it would probably be coveled in a thick atmosphere If It had any available to it. Kaltenegger says we are just at the beginning of understanding the Ghese 581 system. "Pl.:lnets are so hard to find because they look tiny near the star: she explams, "(What's) excitmg 1S we're finding more and mon" planets with this SImple wOOble method_ we can even find the small ones that don't have much mass or are not very big.' Surely as telescopic observations .:Ind computeT technology continue to improve, we'll have the opportunitY to spot more candidates for supporting life like Gliese 581 d or 581 g. We'll be .:Ihle to more prectsely predict how planets move about their stars, and .:Ilso be .:Ible to infer the composiuon of their atmospheres. Learning more about the way «her solar systems formed brings us to a better understanding of what happened here on Earth. Gliese S8l's system, even though It is 20 light years away from us. will therefon" teach us more about our own home.•
147
• 1-',
•
•
-
•
'I,• ...
Into Deep Space
•,
•
'-
.
M!I ~
•
'
/
•
~
•
.'
•
...
;
..
•
-
,
"
•
,-
..
,
,.~.
•
'-
'.
,
.J
• Deepe?t ever VIew of
-
•
,
iii/'. "
,
,
•
.'
,
\.
0(
•
the unIverse
•
Hubble scientists have recorded the history of galaxies in this one image, from soon after the first galaxies were formed to their huge contemporaries j"" ,]!<' 1'"'~I:l.(.,: ,.,>t. "III,,' Cl""\ (',Tl.l"](~.n,,,\ \ I"'" '. ,Ill',· "11:\ ,'r_,' ,'I ,'I ,I'-,lh'd II, (.,II,·d : 11,,-\lh'III'- I ~"'I' f ",1,1, 'I \1 b' ( ''''''IIHlI~
t""
'r ,11,,1 \\,,' ,''''''T11,!,·c1
\",01' ,,1 \A~·\ II,,),-,k ~~,.",.
[,-1,-",,;,,· ~'h'l"~l.ll"" 1" .. ,-,' "I., I','hl- "I '., ,n 1'1<' ,,'nT',- ,I 11,,- "II~'II., 11,,1,1, '0 \ Itt" I~~T f ,,·1,1 I'll' ',q, .'"1 II'I,'~"
·1 J
,,'I.,
I ,'-",' ,-·1
'j'''''' '"
!'h'
"'1,1,- 1.'IL.·n j-, '"I'," 'I,·.,k,~ lJ'I"'; IL:bt,lt· 'I'," " [,.;,.", -,;". ,I..T., I', ·1:' :' " ,~ .,-,,1 :,,, 'I T'J<' :""" tlll . \: 'I WI.'~" ,Ii, ,',\ I' )"'h' " ..... , ,Ii,· 1111", ".,1 '1""I'L"l
"
It'J,'1 In ,I'
~."I·"·'
.;"1.",,,,
',,"',\ ,Ill, I,,·, ,,111'.' ",Il ,,,,I ,;,d.I\I'" "' ')",
"-1.,),1""
:I"',,',,,'
I "', -,." )">'-\1 ,I, '11"'. "': ),\ 'h': I"" ,,10"'; ",.:
,',,"
~'"'''' ",~,.,,_,:,. "\1" "".;1'" ~I I" ;I,;I')'L'" ,,, ];.":: (,"""',h II'.· -\,1\ .111< ",: I •• '1"'1,' 1", 'lll\ ,",' '" hi, has f.,>" I 'I',>,·n ':1 __ 1'1'1, "~''''~ ..,hl :1", \\ Id,' r,,·),.)
150
•
1',1111<'1.1 ..... 1\
J \\h:ch \\.h W,:.lll,'cI
clllll:l,~
Iii..
"'1\
I.,,'
I", "j I)l<' h>I,'" '. 'I'" 1"-' I, 'n,·,! ". ~"I "I
•
•
II", :r1"..'~" "'I''''''-lIh" \ ,lIn"I'),- .h: I' 'II, 'I'",.li :,. ,) '" """" 1.11-0.' LI""! <', ,,1,'III,,!s Il" -11,'"" n·.", ,11, ," tn~ '11·'1,- '11,11' '" h 'i' ~.II.",,·, .W'.·I1~ "hl,11 " " "",dl,Llr.- I< " '11'- tn' ,,1 e1,,1 ,,'11 ~.IL" \ \..t ,11..-'<:'" ,",-d ~h, "LI,: I hh h., (, ,'11 1\1'",) II", ~"I.."
:,,,, ,"" ." I [J, "j~-lf'~"·l I' \"-'I'~ ""'-1 1",1 ,If", ",,1)",'11 It·... , "ll.>' lh,' k.,; f\,,,,~ I" f.., I "1o',T ,,1 111,' ,;.,I."L,·' \ hi)'),· ,,,. '" IIlt'Ll
",T,''', \
In
Ill<' \[1]- -'h' '>-'-\1 "h"n '1,,·, ,11,,l,n.: ,)I'.II""I~I"';
,,11,"1,
1,'~,.. lh·, ,l11,~ Ih,'''' "'1.l~,-, ,.n I..., 1 'li. '''~: "I'''' T·,,· ,,:1>,-- '11, ,',';~ ''''',I.LI :";,-,, 'j"''' ,"Ii,' '"T .1'" 'l', h
.h TIi,· :,"T'~ \\,"--{' 'I',', ,. I,""" 'j .... '" )11, I' ,I' 11.1 f.,. ,;,,·,,111' '11,11 "', ~,.,)~ ,,,,e1 ft'-I, '.. ,., .I'·'·;~·T \ ",''.' nT, TIlt'I::,I'."" ,j 'h,' ,''"' ,>,,,.•
•
•
•
...
Into Deep Space Red dwarfs are the most common type of stilr in our galaxy. but they're
impossible to observe from the Earth with the naked eye because they're the dimmest Slars. They're also very
small and re1.J.tively cool due to their low mass. The red dwarf Proxima
Centauri is among the smallest and dimmest but it has the special
signjflcance of being the closest star to us other than the Sun. Proxima Centauri is approximately 4.24 light years (268.000 AU) away.
located in the Centaurus constellation.
The star is estimated to remain the dosest star to ours for another 30,000 years or so. at which point the star Ross 248 in the Andromeda
constellatIOn will come closer (irs currently about 10.3 light years away). Proxima Centauri is located about 15,000 AU from the next·closest star, the binary system Alpha Centauri This relative closeness is how Proxima came to be discovered. In 1915, Scottish·South African astronomer Robert Innes observed a star that had the same proper motion - the apparent change of a stafs position on the celestial sphere - as Alpha Centauri. which had been first observed in 1689. Depending on who you ask. Proxima is either a companion to Alpha Centauri or a thmi star In the system. Since its discovCly, Proxima has been closely observed. Because irs a
led dwarf. it will be around for much longer than our Sun - at least four trillion more years - thanks to its slow consumption of fuel. And unlike the Sun. Proxima will completely use up its hydrogen dunng the fusion
process. 5.lwlhte X-ray IClcscopt'S haw provided crucial information about its activities. The Einstein Observatory, an X-ray telescope that orbited the E.1rth from 1978 to 1982, took the first X-ray Images of the star and recorded a solar flare - nashes of brightness and heat caused by magnetic actIvity. This confirmed astronomer Howard Shapley's announcemcnt in 1951 that Proxima Centauri was a narc star. The European Space Agency's
European X-ray Observatory Satellite (EXOSAT), German ROSAT, and the Japan Aerospace Exploration Agency's Advanced Satellite for Cosmology and Astrophysics (ASCA) have all observed numerous solar llares on Proxima. Land·based telescopes have also given us data about Proxima. Operated by the European Southern Observatory, the Very Large Telescope (VLT) helped to determine Proxima·s distance and size. The star has a mass about one·eighth that of the Sun·s, but Ii's about '10 times denser. Proxima's corona, or plasma ·atmosphere' extending Into space beyond the surface, can actual1y be hotter than that of the Sun - 3.5 million Kelvin as opposed to 2 mi11ton KelVin. On average, its overall temperature is about 1000 KelVin. Observations of Proxima's chromosphere indicate that it has a rotation period of about 31 days. Although the closeness of Proxima Centauri has made for plenty of observation, there are' still some burning quesllons. Are there any planets orbiting the star? And If so, arc they h.abitable? The Hubble Space Telescope hinted at the possibility of a planet near Proxima Centauri during observations in 1998, but no further evidence has appeared upon subsequent imaging. Proxima was to have been a target of the Space Interferometry Mission (SIMl a NASA space telescope mISSion that ultimately got cancelled. The star's closeness continues to make it a promising destination lor both observation and actual interstellar uavel. and eventually wc'n gel a bettcr look at our neighbouring star.•
All about Proxima Centauri
Into Deep Space
Proxima: inside and out The closest star to our Solar System is also one of the dimmest and smallest red dwarfs Proxima Centaur! isn't just a led dwarf: it's on the lower end 01 lange for latetype M·c!.lSS stars with a mass of just 0.123 that of the Sun. They have dense, opaque interiors. Because of this, late·type red dwarfs have no radiative
zone - an area outsIde the COil' where energy is transferred via radiation present in other types of stars. Instead.
both the core and the outer layer. or envelope, are convective. Energy and hydrogen circulate freely. These
types of red dwarfs contlnue to fuse hydrogen into helium in their cores unt11 it's depleted. In contrast. the Sun
will only use up about ten per cent of its hydrogen supply before it leaves the main sequence and goes into a red giant phase.
Compared to larger, mOle massive stars, the fusion process in red dwarfs is incredibly slow. As a result, the estimated lire span of red dwarfs is
longer than the age of the universe. The lower the mass of the star, the longer its llfellme, so Proxima's estimated life span is approximately 4 trillion years, As the hydrogen fuel is depleted, tile core will contract and It will become a blue dwarf as
"It's one of the most active flare stars ever observed"
158
its temperature rist'S to up to 8.200 degree; Celsius (]4,800 degrres Fahrenhen) and its luminosity increases, giving il a blue appearance. Once the fuel is gone. Proxima Centauri will become a stellar remnant - first a white dwarf. and then a black dwarf as II 00 longer emits heat or lIghl. Due to their lengthy Hie span, the Me cycle of a red dwarf is theoretical. Proxima Centauri IS also one of the most active flare stars ever observed, gencratmg X·ray ('missions similar to those that come from the Sun. This means that on occasion it can suddenly have flashes of int('llSC brightness. Proxima Centauri's flart'S are a release from its magn('\1C field, generated by the convection in the star's interior.
Some scientists have speculated that there is a habitable zone around Proxima Centauri, which would theoretically be a range of about 3.4 mIllion to 8 million kilometres (2 million and 5 million miles) from the Stoll, with an orbital periexl between 16 and 14 days. Red dwarfs emit very llttle light. and any planet in this ?one would probably be tidally locked to the star - with one side remaining in perpetual darkness. This means that there may just be a small region on the planer that is actually habitable, or there would need to be a very thick atmosphere to keep the 'dark' side's temperatures up. In addition, a planet orbiting Proxima Centaun would need to have d slTOng magnetic field to counteract the effects of the star's flales on its atmosphere. Other potential challenges include weather and winds, both of whICh may be harsh: and photosynthesls, which could be a very dIfferent process slnce red dwarfs emit most of their radiation in infrarcct light instedd of vislble hghl. One thing that red dWdrfs have gemg for them is their long life; perhaps even if tlu.'re lsn't d habitable zone around Proxima Centauri now, thefl' could be m the futufl'. During the blue dwarf phase th(' stal will be hotter dOO brighter, possibly allowing for previously uninhabitable planets to become habitable.•
All about Proxima Centauri
Proxima Centauri
innwnbers and figures about Quick facts
our nearest stellar neighbour
Proxima Centauri is around 6.800 times further from the Slll1 than Pluto
4 trillion years Red dwarfstars like Proxima Centawi can last this long because they burn fuel
at a slower rate
• Convective zone Core •
~.1
Because red dWilrf stars have a low mass. they are entirely convective (without the filcHative zone of other stars). Hydrogen fusion takes place within the core and energy moves via circular currents to the outer envelope
The cooler outer layer of the slar also contains hydrogen as well as helium (generated as a fl:'Sl.llt of the fusion procl:'SS). Thl:'
hydrogen circulates bi:lck to the core. where fusion continues for the lengthy main seQuence of the slar
0.0017 7 Proxima's total luminosity over all wavelengths is 0.17"10 that of the Sun
~
million
Kelvin
Although it's The flares on smaller than the Proxima Centauri Sun in mass and can reach this diameter, Proxima temperature is 40 times denser hot enough to radiate X-rays than the Sun
•
Light takes this manyyears to reach the Earth from Proxima 15.
All about Proxima Centauri
;.~~~:;:::
Into Deep Space
•
They're the biggest stars in the universe - cosmic monsters up to a million times brighter than the Sun - so how do supergiant and hypergiant stars push the limits of astrophysics?
Hypergiant stars Look up at the sky on a dark night, and you'll see hundreds of stars. But only a fl'W will really stand out - have you ever wondered why? For some, it's simply because they're quite close to Earth. For instance, Sirius is just 8.6 light years away - so. even though irs a fairly average star (though stil125 times more luminous than our Sun) it appears as the brightest star in our sky. But other stars appear bright because they really are. The second brightest star in the sky, Canopus, is one such star - llO light years from Earth and some 15,000 times more luminous than the Sun. Stars in this class are usually known as supergiants - they have the mass of ten or more Suns, and evolve in a very different way from lower-mass 'Sun-like' stars, living fast, squandering their nuclear fuel and dying young in spectacular supernova explosions. The most massive stars of all, containing many tens or even hundreds of solar masses of material. are hypergiants, the most extrem{' stars known. 'In astronomy I think there's a natural tendency to be attracted to extremes: explains Professor Paul Crowther from Sheffield Univ{,fSlty. -Whether that's the most {'xtreme by physical size, which arc generally tlK> cool red supergiants, or the most extreme by mass, which are the hott<'St and bright<'St blue hypergiants: And Crowther should knowhe's devoted much of his career to studying these st{'llar monsters, and in 2010 discovered the most extreme hypergiant so far, a stellar beacon 165,000 light years from Earth in the indelJ('ndent Large MageHanic Cloud galaxy, an incredible 9 million times more luminous and 265 times more massive than the Sun (see Interview). Supergiants and hypergiants were first discovered through the throretical tools of astronomy - In particular the Hertzsprung-Russell (H-R) diagram which allows astronomers to visualise thl- properties of stars en masse. However, the word 'giant' can be soml'What confusing, because in this case it combines concepts of mass and Size. The largest stars by diameter can all be loosely defined as 'red giants'an evolutionary phase that most stars pass through near the end of their lives, during which they swell to huge diameters (often larger than F..arth's orbit around the Sun) and become far more luminous as they pump out more energy, but conversely tum red thanks to the coolness of their vast outer surfaces. The more massIve a star is, the bigger it will grow as a red
giant, and red supergiants with tens of solar masses (such as VY Canis Majoris, with a diameter larger than Jupiter's orbit around the Sun) are indeed the largest stars of all. However, really monstrous heavyweight stars Il{'Yer actually reach this stage, so while the larger a red giant is, the more massive it Will be, the most massive stars of all ar{'n't actually the largest. The most massive stars are born at the heart of collapsing stat-forming nebulas, wher{' gas and dust are most readily available. UnHk{' the mor{' sedate, Sun-like stars, which form around the edges and coalesce ov{'r many millions of years, these stellar heavyweights grow to their enormous proportions in just a hundred thousand years. The overall amount 01 raw material in the nebula (reflected in the size of the star cluster that ('merges from it) also has a role to play_ 'There seems to be a broad relationship Jx>tween the tOlal mass of a cluster, and the most massive star within it - so for instance the Orion Nebula has a mass 011.000 Suns, and its most massive stars are about 30 times that of the Sun, while the NGC 3603 cluster has about 10,000 solar masses of material, and its most massiv{' stars weigh around 100 soIat masses. We don't know quite why thiS 'mass function' is the way it is In young star dusters, but it seems to be a univetsal rule: says Crowther Competition betwccn the massive central stars seems to act as a throttle to tht> formation process, ensuring that really massive stars are increasingly rare. "The next obvious question is whether if you had an even more massive cluster, would the mass of its biggest star keep going higher?" says Crowther. -And the answer seems to be no - we suspect there's a limit and it's linked to the star formation process. Astar forms in a collapsing nebula. full of competing stellar 'seeds', and it has a limited lime to grab as much material as it can, or else its neighbours will. It's a bit like throwing a handful of sweets into a crowd 01 children - the ones nearest the centre will grab most of them really quickly, while those at the edges hardly get any. It's a competitive environment, and that probably puts an upper limit on how massive a star can get: Another major difference between normal and monster stars lies in the nuclear reactions that keep them shinin.g.ln low-mass stars. these reactions are dominated by the 'prQ(on·prOlon (pop) chaIn', a process in which individual hydrogen nuclei
169
Into Deep Space fuse togeIher one reaction al a Ilme. to eventually prodlJCe nuclei cl helium. the next !leavl('Sl: element The pop chain Il'leases small amounts of energy at every step. but proceeds 1l'J.altvely slowly allowing SUn-like Sial'S to keep stumng for bllhons of years. In more ~ stars.~.
anorhef process called tht CNO cycle becomes Imponant. ThIS fusion chain also convertS hydmeen nuclei Into hehum. bul il: uses carbon I'l.Idet .ts a sotl of 'calalysf, i1lowlllg ltv! re.JCtIOnS to happen at a much folSl:er rate. The CNO cydt ~ Incre.lSlngly dominam at hiihef temptrnu~ and den~.lInd causes ~lght
SIMS 10 shine
many thousands of more boghlly INn their less mass....l" neighbours. 8Ul the &rte lor l1me5
this hnlbara is a drastally shonened
Iilfo span - even lhough their ares contam much It'IOIt' nude,)r futI than rhose of Sun·lIke stars.lTl
supergiants are almost always found at IhI.' heart of newborn star cluSlt'TS 1JK>se C]US[('fS diSintegrate over
ffillbons of years. cwnluaJly scattering theIr Ion~r·lived StiUS over a broad region of spat'('.
but supergiants simply don', live long enough [0 make It OUI of their s[{'lJar nUfS('rics. 'Thl.'Se stars are incredibly rare ttK>y only form in a few places and hall{' very shoTt lifetimes. so even if
you find a star cluster thaI's just 5 millton yt"ars old, its most massive stars will already ha\l(' died: says Crowttxor. i'l'x're's only a handful of really young, massive clusters closeenough to Earth for us to look for thl>se guys and ttK>y're losing mass at a terrific late, 50 ttxo mass we measure dl'pcnds on just how okl ttxo stars happen to tx>. The places wtxore you usually find these really massive clustCfS tend to have enhanced star
This imasr shows ~ spir.ll $lJUC!ure In thematmalaroundtheR~SW
-
Hypergiant stars
I
• Rigel Type: Blue·white ~...-
Solar Radii: 74
I
• V509 C
; iae Type: Yelow IJypefplt Solar bdil: 650
Into Deep Space
~of
gJantstars
Red supergiant The biggest red giants are the largest stars in the universe. swollen to diameters of a billion kilometres or more by changes in their cores as they near the end of their lives. As they swell in size and brighten to hundreds of thousands of times solar luminosity, their
surfaces cool to a distinctive red colour. But many scientists ~ these stars are supergiants rather than true hypergianls.
Yellow supergiant Yellow supergiants seem to be a rare intermediate stage. though again they get their Il<1me from their size and brightness rather
than their mass. They seem to be red supergiants that have shed large amounts of their outer gas as they head towards a supernova v:plosion, In this photo of the 'Fried Egg Nebula', rings of ejected
be Sl't'n surrounding the central star.
material (,In
Blue hypergiant Blue hypergiants are the real heavyweights of the universetens or even hundreds of timl"$ more massive than the Sun, and millions of times more luminoos. Their powerful gravity limits their si~e, so their surfaces are intl!nsely hot Thl! young star c1ustl!r NGC 3603, shown herl!, contains onl! binary systl!m whoSl:' st,us contain a staggl!ring 90 and 120 solar masses of matl!rial,
172
formation ratE'S, usually dUl! 10 galactiC collisions or interactions." So what do supergiants and hyperglanrs look like? TIN! truth is that they're surprisingly varied - while thl! H-R diagram might suggest thai they'd all have E.':memely hot surfaCE'S and appear bluE.' in colour, in reality thE.'Y rangl! across the sjX"Ctrum of colours. Supergiants show the most var~ty, and it seems that their colours simply reflect the preciSl:' balance bl!tween thl! inward pull of gravity and the outward pressure generated by its radiation at a pallicular phase in thl'il ltVl'S. 11l1s b.llancing act. known as 'hydrostatic eqUilibrium' governs a star's overall diameter and therefore its surface arE.'a, even highly luminous Slars can display Sun·like yellow, or {'\len rooler red surfaces if they arE.' largE.' E.'nough for thE.' heating effect of thE.'ir E'SCaping radiation to be thinly spread. Most stars retain more 01 Jess the same mass throughout their lives, and therefore maintain the same gravity, so their equilibrium is mostly affected by chan,ges to their luminosity as the nuclear reactions In lhelr corE'S change and evolve from this, we can work out that bIll(' supergiants arc still close to the 'main scqlll'nre' of stellar evolution, while yellow onE'S have begun to swell In size as tlK;r reach
"The borderland between supergiants and hypergiants is fillea with unusual stars" the end 01 then liv{'S. Red supergiants are even further along their life cycle, and are the largest StMS of all. But lor really massive hypcrgiam stars, there's a different story, Thl.'SC stars never make it across to the red side of the H·R diagram mste3d theIr brilliant radiation generates such huge pressure that II blows their outer layers aWJy Into sp.lcc. exposing thl' interior and ensuring that such stars remain hot, maintaining blue or whlte·hot surfaCE'S thlOughoulthcir ltves. ThIS strong outnow of hydfOll{'n· lich material gives Itself away In a hypergiant's spe'Ctrum and Is one of the key means of disl1nguishlng them from really bright supergiants. The borderland between supergiants and hypergiantS is filled with a strange variety of unusual stars. and no tWO astronomers really agree on the plecise divkhng lines between them. For e~.lmple, luminous blue variabl('S are extremely bright stars that show long, slow changes m brightness with oa:asional outbursts, and include both supergi.lnl and hypergiant stars.
Most 01 the rare so·c.llled 'yellow hypcrglanlS', desplle their name, actually seem to be red supergiants that are shedding their outer layers "nd heating up. And, as we've seen, aStronomers also dlffer about whether red hypergianls even exist! Depending on thelr featurE'S displayed in their light. other categor!es of supelgiant 01 hypcrgi.lnl bear eltolic n.lmes such as Wolf·Rayet stars and Ofpe stars, However, until recently, the only certall'l means of weighing really massive Slars, and ldentlfyll'lg sUpt'rgianls and hypt'rgial'lls. was to pkk them OUt in binary systems. Here, the orbital motions of the tWO stals can be used to calculale thell masses. Fortunately, a recent breakthrough in modelling the 'oehaviour of really highmass stars promises to remove some of thest' hmitations (see IntervieW). Supergiolm and hyperglJnt star> live fasr and die young. but what fate awaits them at the end of theh Uves? Once a srar has exhausted the hydrogen fuelll'l its COte, it has reached the end of liS main sequence hfetlme
Star classification One of the most useful tools for classifying stars is the Hertzsprun.g-Russell (H-m diolgram, It plots stars according to their surfa«' lempt'~ture and roloul or 'spedlid type' (on the horizontal axis) and their luminosity (on the vertical a.xis). When a large number of randomly selected stars are plotted, a pattern soon emerges: most stals .lre arranged along a diagonal ribbon known as thE.' 'main sequE.'l'lCe·, that runs betW('{'ll the faint cool and red and the bright, hot and blue. Luminous cool stMS and faint hot ones ('led giants' and 'white dwalfs') occupy regions to either side of the main sequencE.' and are comparatively lare.
1. Main sequence I' This is the region where stars spend the majority of their lives - a star's position on the main sequence is largely ! determined by Its mass. i
SPECTRAL CLASS
Btue supergiant. Alnil.:lm
Blue giant Eta Aurigae
2. Red giants Most stars pass through this phase near the end of their lives, brightening and developing an atmosphere with a cool surface.
Sirius
R'd,!a ArcturuS.
,,,
Alpha Centauri B Red dwarf. _ Proxma Centauri
White Dwarf, II _Sirius B
""""=~~
TEMPERATURE
I
.
! S
3. White dwarfs i 4. Supergiants These hot stars are faint These high· mass stars are Decause of their tiny size brilliantly luminous and they are the burnt
Hypergiant stars
Structure of
a supergiant
•
Monster star The largest red supergiants can grow to diameters larger than Jupiter's orbit around the Sun
Red supergiant. A fed ~upergianl is a high-mass star that is nearing the end of its life and has long Since exhausted the supplies of hydrogen fuel for fusion in its core
•
Still burning
•
The star's core keeps generating energy by fusion of heavier elements, growing denser over time
Fusion shells Meanwhile. nuclear fusion of lighter elements spreads out in a series of shells around the core
•
Outer envelope The huge amounts of energy coming from the core and its surrounding shells cause the star's upper Ia~rs to balloon in size
'\
Cool surface • The star's enormous size gives it a huge
•
surface area. so despite pumping out huge amounts of energy. the surface remains relatively cool and appears red
Convection cells Huge currents within the outer envelope create rising and sinking masses of hot and cool gas, often giving the star's surface a blotchy appearance
Iron core. - - - - - - - - - - , JUSl before the star dies. a core of solid iron begins to build up. Unlil
Heavier shells. Closer to the core. heavy elements continue to fuse into still heavier ones. allowing the supergiant to keep shining
Helium fusion. A second shell of helium fusion follows the hydrogen shell out into the star, creating heavy elements such as carbon and oxygen
Hydrogen fusion shell • - - - - ' Changes in the star's density and temperature allow hydrogen fusion to continue in an expanding shell around the core after hydrogen in the very centre has been exhausted
m
Into Deep Space
surroundIng the core. and heavier ek'menlS in the rore itself. These' pIllCeSSeS cause the dying SlitT 10 brighlen and SWl:':IL shilling illowards 'red suPE'fBlo1nf lerT1lOfy. whde ~s core develops OJ complex Llyered smnure
of tnCre.lsmgly heavy elements. Each new phase of fusion produces Itss energy tlwn the prevIOUS Olle'. oind is exhausted man! ~ickly. Wt the liIIl:lIatlon thal conllnues to pout from the core sUll helps 10 support I: .agaInst ItS own enormous griMly
ThaI all change; when {he SIal altempu; to fuse Iron· lhe ~ eEmenl ~ fusion ilbsc:xbs tnergy AbruiXJy. the Sla(s ~ supply falters and dIeS. and (he hu8e wetghl oIllS Olliei' \ayers comes cr.uhing down. In wh.:Il is known as,)'~ coI1apse supemo·.... (he irorHICh core is compressed 10 01 uny SlU, whj~ a uemendous shockwa~ rebounds through the remainder of lhe S1M.
he.:mng and compressllli It untlilhe whole star ignius In it blaze of nuclear luSlOfl mol.! lThly lasl ror months and outshine,) billion stars. As the SUPCH1OVoJ fades and (he debns dears. the compressed rt'rn.lIllS of the COrt'
may be rcvcaled as a super-dcnse neutron stilr. or even a black hole But. lor the most massive stars of illL there may be a third option. "ThronslS lell us lhal if a star dies with roughly 200 solar masses of material remaining. It could juSt blow up ~ it wouldn't be the usual core-rollapse event. but.l 'p.:lir·instabllity supernova', which would blow itself to bits before It could form a super-dense core. These things would be alThlzlngly bright and there have been a lew observations of events that might be this kmd of 'superlumlnous supernovi: So. while they may be r.lre, these monster SI'US are certainly makmg their presence felt· and interest Is only likely to increase in the next few years. Astronomers believe that supergiants and hypergiants wcukl have been far more wklespread m the early umverse, when the 1ac:k of heilvy elements wcukl hav~ gwen them a more compact structure with a hol:ter surfin'. Thanks to the exparwon 01 the umverse. the ulttoiMOk't: r.ldJalIOll that poored from the surface 01 these superhot stars shoukl now be sH~Ched Of 'Doppler-shifted' to mfrared waY'Clengths. Here it shoukl be VlSibie 10 NASA's James Webb $pin Telescope when it launches In 2018 to gl~ us OUt first YteW 01 the e.lrl~ stellar generallons, •
U4
Enjoyed
this book?
Exclusive
rfornew
* This offer entities new UK Direct Debit subscnbers to receive their first 3 Issues for £5. After these Issues. subscnbers will then pay £17.95 every 6 Issues. Subscnbers can cancel this subscnptlon at any time, New subscnptlons will start from the next available Issue. Offer code 'ZGGZIN' must be quoted to receive this special subscnptlon pnce. Direct Debit Guarantee available on request. ** This 15 a US subscnptlon offer. The USA Issue rate IS based on an annual subscnptlon pnce of £50 for 13 Issues which IS equivalent to $78 at the time ofwntlng compared with the ne'NSstand pnce of $9.99 for 13 Issues being $129.87. Your subscnptlon will start from the next available Issue.
The ultimate astron9my magazine
---
The latest news Stay up to date in the world of space with informative news articles packed with useful facts and inspirational images
Ii
,,' In-depth features
• ••
I
•
Learn about deep space, the solar system. space exploration and much. much more
subscribers to... All About . DEEP SPACE I SOLAR SYSTEM I EXPLORATION
Try 3 issues for £5 in the UK* or just $6 per issue in the USA** (saving 40% off the newsstand price)
For amazing offers please visit
www.imaginesubs.co.uk/space Quote code ZGGZIN Or telephone: UK 0844 826 7321 Overseas +44 (0) 1795 414 836
•
•
eunlVe In our an s
All About BUY YOUR COPY TODAY Print edition available at www.imagineshop.co.uk Digital edition available at www.greatdigitalmags.com Ijlacebook.COmflmagineBookazines
W
twilter.comlBooks_lmagine
