All_About_Space_-_Issue_94_2020

Whyisitessentialwefindoutmoreaboutthe

icegiants,UranusandNeptune?

UranusandNeptunehaveneverhada dedicated

spacecraftmission,havingbeenvisitedonlyonce

bythebrieff lybymissionofNASA’sVoyager 2

spacecraftthreedecadesago.Thesedistantice

giantsaretheleastexploredtypeofplanetin

ourSolarSystem,intermediatebetweenthebig

hydrogen-richgasgiants– JupiterandSaturn–

andthesmallerrockyplanets.Yet,Neptune-sized

worldsappeartobecommonplaceinourgalaxy,

a naturaloutcomeofthechaoticprocessofplanet

formation.Amissiontotheseicyworldsisthe

logicalnextstepinhumanity’sexplorationof

our planetary system, to understand how Uranus

and Neptune formed, to explore their deep water-

rich interiors and exotic hot ices, their stormy

atmospheres and their complex magnetic fields,

which are totally unlike anything witnessed at

Jupiter and Saturn. 

The two worlds are superb examples of how

planets with shared origins can go down different

evolutionary paths:  Neptune as the archetype

for ice giants with its seasonal tilt and powerful

winds;Uranusastheoddballwithitsextreme

tiltedinclinationandsluggishatmosphere.And

bothworldsharbourdiversesatellitesystems,

fromUranus’collectionofnaturalicysatellites

withevidenceofextremegeologicalactivityto

Neptune’scapturedsatelliteTriton,a visitorfrom

the more distant Kuiper Belt which may harbour

a subsurface ocean and exhibits erupting geysers

from its surface. For all these reasons and more,

scientists across the globe are urging their space

agencies to mount an ambitious robotic mission to

explore these worlds in the coming decade.

Dr Leigh Fletcher is a senior research fellow

at the University of Leicester who

specialises in understanding the giant

planets in our Solar System

BepiColombowillbeperfectto

followuponNASA'sMESSENGER.

BepiColombohasseveral

instrumentsnotpresenton

MESSENGER,suchasthe

thermalinfraredspectrometer,

anaccelerometer,a dual-band

radio-scienceinstrumentandthe

plasmainstrumentsonthesecond

Japanesespacecraft,Mio,inorbit

atthesametime.

TheESA’sMercuryPlanetary

Orbiter(MPO)andJAXA’sMercury

MagnetosphericOrbiter(Mio)

complimenteachother.Whilethe

MPOismorefocusedonstudying

theplanetitselfanditsinterior,

theMMOisfocusedonstudying

theplasma,particleandmagnetic

environmentaroundtheplanet.

ThereforetheBepiColombo

missionwillprovidea rare

opportunitytocollectmulti-point

measurementsfromtwocraftina

planetaryenvironment.

I stronglybelievethatthe

instrumentationofBepiColombo

isperfectlysuitedtoobtainour

sciencegoalsandtodeliver

answerstothenecessaryandnew

questionsraisedbyMESSENGER.

DrJohannesBenkhoff

worksattheESAandis

projectscientist

oftheBepiColombo

mission

Howdoes

BepiColombo

improve

onNASA’s

MESSENGER

spaceprobe?

@spaceanswers /AllAboutSpaceMagazine [email protected]

©NSAS/JPL

© Tobias Roetsch

SOLAR SYSTEM

“ Neptune-sized

worlds appear to be

commonplace”

Did

youknow?

Uranusiscomposedofaround 83

percenthydrogen, 15 percent

heliumandtwopercentmethane.

Neptuneisaround 80 percent

hydrogenand 19 percent

helium.

Uranus and

Neptune are the

least observed

planets in the

whole Solar

System

SPACE EXPLORATION

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