BBC Focus - 04.2020_

FEATURE WHAT HUBBLE TAUGHT US

Hubblehaschangedthewayweseeour

cosmicneighbours,asit workswithother

probes to bring our Solar System into focus

THE PLANETS

A NEW PERSPECTIVE ON

NASA/ESA/A SIMON/GODDARD SPACE FLIGHT CENTER, NASA X4

ABOVEThese

imagesrevealhow

muchSaturn’s

auroraechangein

thespaceofjust a

few days

28 Jan 2004

Jan 26, 2004

24 Jan 2004

T

heSolarSystemis ourcosmicbackgarden.It shouldbeone

ofthebest-knownpartsofourcorneroftheUniverse.Yet

whenHubblelaunchedin 1990 ourplanetaryneighbourhood

wasstilldeeplyshroudedinmystery.Lookingupfrom

Earth,theever-shiftingatmosphereblurredourviewof

theplanets,makingit difficulttoseetheirfeatures.Abovethe

turbulentair,Hubblecouldwatchtheseworlds in peace and has

beendoingsoforthelastthreedecades.

ThislonglifehasbeenoneofHubble’sgreatestassets,making

it possibleto revealtheweatherandclimatepatternsof changing

seasonsonoursisterworldsastheymaketheirjourneysaround

theSun.TheHubblescienceteamhastakenadvantageofthis

uniquelongviewbyundertakinga project called the Outer

PlanetAtmospheresLegacy(OPAL).

“OPALemploysHubbletolookeveryfewmonthsatJupiter,

Saturn,UranusandNeptunetoseeif they’vechanged,”says

JenniferWiseman,Hubble’sseniorprojectscientist.“Through

OPALwe’velearnedhowtheGreatRedSpotonJupiter,a giant

storm,is actuallyshrinkingandchangingcolourovertime.We

seenewstormscroppingup,andweseethemcomingandgoing

onsomeoftheotherouterplanetstoo.Studyingthechanging

natureoftheplanetsinourSolarSystemissomethingthat

Hubbleis enablingus to do through both its clarity of imagery

and its longevity.”

MISSIONSUPPORT

Ofcourse,Hubblehasn’tbeentheonlyonewatchingtheplanets

overtheyears.Sinceitslaunch,dozensofmissionshavebeen

sentacrossourSolarSystemandHubbleis oftencalleduponto

supplymuchneededcontext.WhenCassiniarrivedat Saturnin

2004,it couldonlyseesmallpartsof theplanetat a time.Hubble,

however,wasabletotakeintheentireplanet.Whilethiswasat

a muchlowerresolution,thetelescopewasabletotrackstorms

andauroralactivitytohelpplanetary scientists understand the

dataCassiniwassendingback.

“This profoundly improves the science return from any of

theseparticularmissions,comparedtothem

operatingontheirown,”saysWiseman.

MarshasbeenanothertargetofHubble’s

attentionsasit worksinconcertwiththe

armadaofspacecraftonandaroundtheRed

Planet.Thetelescopehashelpedtotrackthe

hugeduststormswhichblowacrosstheplanet

everyMartianyear.Onceagain,thisgivesa

globalappraisalof thestorm’sprogresswhile

thein-situprobesnotelocalisedchanges such

astemperatureandpressure.

It’snotjustduringmissionsthatHubbleoffers

support,however.Foralmosteveryplanetary

missionofthelast 30 years,Hubblehasbeen

usedtoscoutthewaybefore the spacecraft

evenreacheditstarget.

“Hubblewasusedtohelpinplanningthe

NewHorizonsmissionwhichpassedbythe

Plutosystemin2015,”saysWiseman.“The

spacetelescope’sobservationshelpedinform

theplanningof thatprobe’s trajectory and get

it safely to Pluto.”

EYEINTHESKY

BeforeNewHorizons’approach,theoperations

teamfearedflyingintoanunseenmoonor

otherobstaclearoundthedwarfplanet,andso

usedHubbleto searchforpotentialhazards.It

wasduringthiscampaignthatHubblerevealed

thepresenceof a pairof moons,NixandStyx,

allowingNewHorizonsto plot a trajectory

whichavoidedthem.

Hubbleoffersanotherperspectivethatmany

of theseplanetaryspacecraftlack– theability

toobserveintheinfraredandultraviolet.For

the Juno mission at Jupiter this capability 5

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