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:malcolm71@mac.com–  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