Mars’ fleeting atmosphere
TheSun’sharmfulradiationandsolarwindsaresomethingthat
haveonlybecomeapparentveryrecentlyonEarth,especiallyas
weincreaseourtechnologicalpresenceinspace.However,NASA’s
MarsAtmosphereandVolatileEvolutionMission(MAVEN)orbiter
discoveredthatitwasthissameintensebombardmentthat
strippedMarsofitsatmospherebillionsofyearsago.
AstudyinMarch 2017 usingMAVENdatashowedthatMars
hadlost 65 percentoftheargoninitsatmospheretosolar
windandradiation.Theknock-oneffectsmeantthatMarslost
itsprotectiveblanket,andwithoutanatmospheretotrapheat
orshieldfromultravioletradiation,alltheliquidwateronMars
waslost.ThisiswhyMarsiscoveredindried-upriverbedsand
mineralsthatcouldonlyexistwiththepresenceofliquidwater.
ThisdiscoveryshatteredtheperceptionthatMarshasalways
beenthedry,red,dustyplanetthatisseentoday.Finding a
hidden oasis
OnecommongoalofMarsexplorationmissions
isthehuntforliquidwater.Withoutliquidwater
therewouldbenolifeonEarth.Astronomershave
nowwithoutadoubtproventhatthesameliquid
wateronceflowedonayoungerMars.Thanksto
theEuropeanSpaceAgency’s(ESA)MarsExpress
orbiter,astronomershavefoundliquidwaterhidden
underneaththesurface.
Usingtheorbiter’sMarsAdvancedRadarfor
SubsurfaceandIonosphereSounding(MARSIS)
instrument,astronomerswereabletoprobe
thepolaricecapsonthesouthpoleusingradar
soundinginstruments.Theyfoundthat1.5
kilometres(0.9miles)undericeanddustwas
liquidwaterspreadingoutover 20 kilometres(12
miles).“ThissubsurfaceanomalyonMarshasradar
propertiesmatchingwaterorwater-richsediments,”
saidRobertoOrosei,principalinvestigatorofthe
MARSISexperiment.“Thisisjustonesmallstudy
area;itisanexcitingprospecttothinktherecould
bemoreoftheseundergroundpocketsofwater
elsewhere,yettobediscovered.”
Thisisatremendousdiscovery,asitnotonly
solidifiesthetheorythatwaterwas– orinthiscase
is– onMars,butthiscouldhavemajorimplications
fortheeventualhumanexplorationofMars.Peaking above the dust clouds
AlongwithobservationsofMars’‘canals’inthe19thcentury,
Schiaparellialsoobservedmoreenormousfeaturesusinghis
22-centimetre(8.7-inch)telescope– theMartianmountains.The
TharsisregionofMarswasmostdocumented,a hugevolcanic
plateneartheplanet’sequatorandhometothemostenormous
mountainintheentireSolarSystem:OlympusMons.
Infact,evenwhenMariner 9 madeitsjourneytotheRed
Planetin1971,itwasabletospotthetopofthemountainpoking
outfroma globalduststorm.
OlympusMonsisroughly 25 kilometres(16miles)talland
stretchesover 624 kilometres(374miles)ofland– aboutthesize
ofArizonaintheUnitedStates.ThisgiantputsanyEarth-based
mountainstoshameatthree-timestheheightofMountEverest.
ThediscoveryofOlympusMonswasanexcitingoneasit
posedastronomerswiththechallengeofexplainingitsevolution.
Indoingsoastronomershavediscoveredthatalthoughithas
beenformingforbillionsofyears,somepartsofitarestill
relativelyyoung– onlya fewmillionsofyearsold– andpossibly
stillactive.Instead of a
violent eruption,
Olympus Mons
would just have
lava slowly flow
down its sidesThe early Martian
environment was a
very different sight to
Mars today© ESA© NASA© USGSMars