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Astrobiology
MalcolmFridlund
TheTeacher• MalcolmFridlund–Swedish,livedintheNetherlandsandGermanyatotal
of29years• Ph.Dastrophysics,1987,StockholmbutstudiedinStockholm,Groningen
andOnsala• AtESTECbetween1988and2013• GuestProfessorinBerlin(DLR)2013-2014• GuestProfessorinHeidelberg(MPIA)2015• ProfinLeiden(SpaceObservaXonsofExoplanets)since2010• ProfatChalmers(RadioastronomyandAstrophysics)since2014• StarformaXon,Interferometry,Astrobiology,Exoplanetology,Stellar
physics
Structureandoutlineofcourse• 9lessonsinHL20713:45to15:30• Form:Lectures,lecturenotes(VG’s)someexercises• EveryThursday• Wri^enexam
• Contact:[email protected]– Tel0651-408529IaminLeiden(SterrewachtorESTEC)alsomostTuesdays,Wednesdays
ObjecXvewiththecourse• Thecourseisintendedtogivea(relaXvely)complete
overviewofthebasicsofAstrobiology,aswellassomeideaaboutfuturedevelopments
• ThisincludesahistoricalbackgroundandmoXvaXonforstudy• ThedifferentsciencesthatformpartofAstrobiology• Thecurrentandfutureground-andspace-basedobservaXons
Course structure
Thecourseisnowbuiltuparoundthefollowingcoreelements:
#1Introduc,on:Overview,LifebeyondtheEarth,LifeinthesolarsystemvslifeintheUniverseasawhole.HowcansciencehelpusanswerthefundamentalquesXonsconcerningwherelifecomesfromandhowitisformed?WhereandhowdowesearchforlifeoutsidetheEarth?Astrobiologyisanewscience-howdoesitestablishitself?
#2Backgroundandhistory:Theancientideas(e.g.Plato),TheCopernicanrevoluXon,Enlightenmentvsreligion,Themodernideas.Astrobiologyturnsintoascience.
#3Theastronomicalcontext(“Astronomy101”):Thislessonisintendedforboththosewhocometothecoursewithli^leornoknowledgeoftheastronomicalcontext.ButitisalsointendedandusefulforstudentswhohavestudiedastronomybecauseitprovidesanotherperspecXve.Instruments,SpaceAssets
Course structure
#4-#6TheEarth,Exoplanets&Habitableplanets:WhyistheEarthanabodeforlife?,i.e.Whyisit‘Habitable’?HistoryofthelifeonEarth.HowdidtheEarthgetanatmosphereandoceans.Earlylifeandgeology.Climatechanges(natural)anditsimpactonlife.ExXncXons.WhatdowethinkwillbethemostinteresXngplacestolookforlifeoutsidetheEarth?OrbiXngreddwarfstars?Howdowefindplanets?Andwhydowethinkweneedplanetsinordertohavelifeatall.Whathavewediscoveredsofar.
#7Planetforma,on:Howdoyoubuildahabitableplanet?Howdoyoufindahabitableplanetandhowdoyousearchforlifeatinterstellardistances?
Course structure
#8TheSolarSystem:Lifeinthesolarsystem.Howdoyoufindit?Mars?,Jupiter’smoons?,Titan?ExploraXonoftheSolarSystem
#9Contact:SearchforIntelligentlife(SETI).InterplanetaryandInterstellartravelinthiscontext.Repetition, Discussion and rehearsal for exam
Lesson1
• IntroducXon• LifeinthesolarsystemvslifeintheUniverseasawhole
• HowcansciencehelpusanswerthefundamentalquesXonsconcerningwherelifecomesfromandhowitisformed?
• WhereandhowdowesearchforlifeoutsidetheEarth?
• Astrobiologyisanewscience-howdoesitestablishitself?
Lesson1
ArewealoneintheUniverse?
LifebeyondtheEarth?
• SomeXmesIthinktheUniverseisfulloflifeandsomeXmesIdonot.Eitherwayisequallyamazing–ArthurC.Clarke
• 341–270BCEpicuros“Wemustbelievethatthereareotherworldsandthatthereislifeonthem–somesimilartooursandothersthatarequitedifferent”
• ButAristotelearguedthatthiswasNOTthecase• Justafewexamplesmorethan2000yearsapartdebaXng
aboutlifeintheUniverse-BasicallythequesXonwaswhetherwearealoneorunique?ThishadandconXnuestohavegreatphilosophicalimplicaXons
• ButisitreasonablenowtoimaginelifebeyondtheEarth?
The birth of the belief in other worlds
“Thereareinfiniteworldsbothlikeandunlikethisworldofours…”Epicurus(c300BC)
“…falseanddamnable…”G.Galiliei(born1564)
“TherearecountlesssunsandcountlessearthsallrotaXngaroundtheirsunsinexactlythesamewayasthesevenplanetsofoursystem…ThecountlessworldsintheuniversearenoworseandnolessinhabitedthanourEarth”GiordanoBruno,1584inDeL'infinitoUniversoEMondi
‘BigQuesXons’
“WhatistheuniquenessofourownEarth?”
“Arewe(lifeforms)alone?”
“Whatisourpast&future?”-TheformaXonofplanets-TheevoluXonofplanetarysystems
Cosmic Vision is centered around four Grand Themes: 1. What are the conditions for planet formation and
the emergence of life?
• From gas and dust to stars and planets
• From exo-planets to biomarkers
• Life and habitability in the Solar System
2. How does the Solar system work?
3. What are the Fundamental Physical Laws of the Universe?
4. How did the Universe originate and what is it made of?
Cosmic Vision is centered around four Grand Themes: 1. What are the conditions for planet formation and
the emergence of life?
• From gas and dust to stars and planets
• From exo-planets to biomarkers
• Life and habitability in the Solar System
2. How does the Solar system work?
3. What are the Fundamental Physical Laws of the Universe?
4. How did the Universe originate and what is it made of?
First: In-depth analysis of terrestrial planets. Next: Understanding the conditions for star & planet formation, and the origin of life. Later: Census of Earth-sized planets, exploration of Jupiter’s moon Europa. Finally: Image terrestrial exoplanet.
LifebeyondtheEarth?
• ThereisagreatgeneralinterestinthequesXon:– Viz.Films,TV,UFO’s,PersistentrumoursaboutArea51,etc.
• ButalsoscienXstsareinterestedforanumberofreasons:– WedonotreallyknowhowlifearoseontheEarth– WedonotknowwhattheroleoflifeintheUniverseis– WedonotknowmanyoftheevoluXonarystagesonEarth
• ItisclearthatthediscoveryofanykindoflifeoutsidetheEarthwouldhaveanenormousimpact
LifebeyondtheEarth?
• Sowhatarewegoingtolookfor:– TheintelligentlifeportrayedinfilmslikeStartrek?Orourselves?
– GiraffesPlatypusorHamsters?– SimpleonecellularlifelikethatinhabiXngourEarthformostofitshistory?~4Gyrs
• Alloftheabove–ThehistoryoflifeonourEarthmakesthatclear.Modeledonourownexperience
• Caveat:SomehowwewillhavetoaddressthequesXonthatlifewillbeverydifferent(Oblivion)
Astrobiology
• Whatisastrobiology?– Astrobiologyisthestudyoftheorigin,evoluXon,distribuXonandfutureoflifeinthewholeUniverse
• Howcanitbeaddressed?– BystudytheeventsontheEarth,bysearchingforsignsoflifeontheplanetsintheSolarSystem,bysearchingintherestoftheUniverse
– ByusingacrossdisciplinarymethodincludingeverythingfromgeophysicstoSETI
LifebeyondtheEarth?
• ButtheissuesarealsointeresXngwhenconsideringlifeontheEarthitself
• WedonotknowwhenorhowlifearoseonEarth• Weknowveryli^leabouttheevoluXonoflifeforthefirst~4Gyrs
• Wedonotknowwhyaper~4Gyrwehadthe“CambrianExplosion”
Astrobiologyisanewscience-howdoesitestablishitself?
Astrobiology
• Byclarifying,eventually,oneofthegreatquesXons:ArewealoneintheUniverse?
�BydemonstraXngitsvaluetounderstandlifeonEarthanditsevoluXon
� BydemonstraXnghowwecanunderstandtheevoluXonoftheSolarSystemandEarthitself
�BydemonstraXnghowitcanhelptopredictthefutureevoluXonoftheSolarSystemandlifeinit
HowcansciencehelpusanswerthefundamentalquesXonsconcerningwherelife
comesfromandhowitisformed?
LifeontheEarth?
• ThreeimportantquesXons:• Whatislife?• WhendidlifebeginontheEarth?• AndhowdidlifeariseontheEarth?
Whatislife(Clausius,1865)
• Clausiusformulatedthefirsttwolawsofthermodynamics
• 1:TheenergyoftheUniverseisconstant• 2:Theentropy(degreeofdisorder)oftheUniversetendstoamaximum
• Boltzmanspeculated:“Thegeneralstrugglefortheexistenceofanimatebeingsisnotastruggleforrawmaterials,norforenergy,butfornega4veentropy,availablebythetransiXonofenergyfromthehotSuntothecoldEarth
WhatislifeSchrödinger’sparadox(1944)
• Inaworldgovernedbythe2ndlawofthermodynamicsisolatedsystemsareexpectedtotendtoastateofmaximumdisorder.
• Lifeapproachesandmaintainsahighlyorderedstate–doesthisviolatethe2ndLaw.Aparadox?
• Lifeisnotanisolatedsystemènoparadox.Whynot?• Theincreaseoforderinsideanorganismiscompensated
morethanenoughbytheincreaseindisorderoutsidethisorganism.Thehighlyorderedstate,issustainedbycausinganetincreaseindisorderintheUniverse.
• ThecomplexityonEarthcausedbyliferequiresenergymostlyprovidedbytheSunandsupernova(radioacXvity)èincreasesentropymorethanlifediminishit
WhatislifeSchrödinger’sparadox(1944)
• SoweliveincloseconnecXonwiththeUniverseandnotseparatefromitinanyway
• LaterwewillseethisagainwhendiscussingphotosynthesesandhowthisconnectlifeonEarthwiththeSun
• IstheUniverseintendedforlife?ThisisabigissueinCosmology
• ParallelUniverseswithdifferentnaturallaws(aninfiniteamount)solvethisissue
LifeontheEarth?–Whatdoweknow
• TheEarthformedabout4.54Gyrago• Earliestundisputedsignsoflifearefossilmicrobialmats(Stromatolites)from3.48Gyr(Australia)
• Biogenic(?)Graphiteinsedimentary?3.7GyrrocksinGreenland
• Twootherstudiesfindsigns(fossil12C/13CraXos)from4.25and4.4Gyr
• èLifearoseEarly?ImplicaXons?
Abriefhistoryoflife
• AlllifeonEarthisprobablyrelatedandgoesbacktoa“firstcell”~4Gyrsago
• Theoldestfossilsareprobably(thestromatolites)simpleone-cellularwithnonucleus(~3.5Gyr).Procaryotes
• 2Gyrscellswithanucleusevolved.Eucaryotes• MulXcellularlifeareknownfrom650–542Myrsago.The
firstsignsarefossilisedtracksofwormlikelife• 542MyrCambrianexplosion(TheBurgessshale)• Organismswithshellsand(exo-)skeletonsappear• FirstVertebrates(488-416MyragoOrdovicium),Jawlessfish
Abriefhistoryoflife
• Firstplantsonlandnotlaterthan444-416Myrago(Silur)• Firstfrogs416-359Myrago(Devon)• Firstmammals251-200Myrago(Trias)• Firstprimates(endofCretaceus)66Myrago• SeparaXngfromourcousins(Chimpanzees)7-6Myrago• HomoErectus~1Myr–143Kyrago• HomoHeidelbergiensis(thebrightestofthelot),
Neanderthalensis,Denisovans800Kyr–40Kyr• HomoSapiens200Kyr-.....
Howdoweanswerthe’big’quesXons?WhyofftheEarth?
• Probablynotbystudyingourownplanet!Theevidenceisgone!(impacts,tectonics,recyclinginextrenum)
• Otherplanetsinthesolarsystem–maybebutuncertainwhatthismeansforthequesXon:LifeintheUniverse!
• Studyalargenumberofother(exteror)solarsystemsanddetermineiflifeexistelsewhere!
LifebeyondtheEarth?
• MaybeweshouldstartintheSolarSystem– MarswaslongconsideredthebestchanceforlifeintheSolarSystem
– Straightlinesobserved(1877)criss-crossingthesurface–Canali=channels=canals
– Lowell(1894)builtlargeobservatoryandmappedthousands“canals”,“carryingwaterfromthepolestoadyingplanet”
– Radioshowof“Waroftheworlds”in1938causedpanicintheUSA
LifebeyondtheEarth?
• Butthecanalsdoesnotexist–MarinerIV(1965)
AbleakworldwithextremelythinatmosphereofahosXlecomposiXon
LifebeyondtheEarth?
• MarinerIV(1965)+atmosphericanalysisinthe50:XesèNoLife
• Viking1&2in1976soplandedontheplanet.Eachcarried3experimentstolookformicrobes.AmbigousdetecXonsprobablytheresultofstrangechemistry,cool,bleakandtotallydryplace
• Newsetofmissionsbeganin1997andconXnuetoday,landers,roversbutnosignsoflife
• Evidence,however,forliquidwater,onawarmer,we^erMarsinancientXmes
Document title | Author Name | Place | Data doc | Programme | Pag. 34
FIRSTEUROPEANMISSIONTOMARS(2003–)MarsExpress
• Returningbreathtakinghigh-resoluXon3Dimages
• FirstmissiontoprobebeneathMarXansurface
• Findingwatericeandtracesofmethane,possiblecondiXonsforlife…
MARS EXPRESS
LifebeyondtheEarth?
• MarsexploraXonconXnues• Newspacecraparriveevery2years• Analysisofsamplesin-situhasfailed–nextstepissamplereturnwhichwillhappenwithin5years
• Meanwhile,preparaXonsforhumanexploraXonconXnues,slowlybutcertainly
• But,wemayhavetogooutsidethesolarsystemtosearchforlife....
• Howdowedothat
Butthinkaboutthis:IfatthemomentweknowonlythatlifeexistatoneplaceintheUniverse–Whatdoesittellusifwefindoutthatlifearoseonone(ormore)otherplanetsinthesamesystem?
TheexploraXonoftheSolarSystemwillbedescribedinmoredetailinalaterlecture
LifebeyondtheSolarSystem?
• Wewillhavetouseremotesensing–atleastfornow– Youwillhear(ali^le)laterinthecourseaboutpossiblefuture
starships
• Thismeanswehavetofindsuitableplacestosearchforlife– ThislikelymeansplanetsorbiXngstarsotherthanourSun.Thecourse
willdescribethissearchasithasbeengo^enunderwayinthelast20years
• Andwehavetodefinebiomarkers–signsofbiologicalacXvitythatisvisibleacrossinterstellardistances
Astrobiology–typicalquesXonsforothersystems
• So,howfastdidlifeariseontheEarth?(107–>108years?)
• Iforiginoflifeisasimpleprocess–MaybeithappenedseveralXmesontheEarth?
• Aretheregoverningprinciplesfortheoriginoflife–ontheEarth,intheSolarSystemandintheUniverse?
• IfsimpleunicellularlifeformedquicklyandmulX-cellularcomplexlifetakeslonger(Cambrianexplosiontookplace3-3.5x109yrsaperoriginoffirstlife)-Whatdoesthisimply?
If we can not answer these questions on the Earth – then what?
Spectroscopy will be key in order to look for biomarkers in deep space?
Biomarkers
The goal is to find rocky planets with an atmosphere out of photo-chemical balance.
(cf. Lederberg, 1965 and Lovelock, 1965)
Working definition:
Life ≡ O3 + H2O + CO2
Ideally, detect reduced molecules (CH4, N2O) as well
A plan to go for?
Look for oxygen
Look for liquid water
Analyze the reflected light from the planet to see if the planet has an atmosphere
Look for other signs of biological activity (methane)
and rule out all other explanations. 17
EvoluXonisimportant
• Wewillneedtheagesofthesystems• Withasignificantimprovementinprecisions• Howdowedothat?
SoWheredowelook?
Astrobiology
End of lesson