Theimpacthasslightlydegradedoneoftheobservatory’smirrorsegments,butNASAsaysthetelescopehassustainednosignificantdamage
NASA’snext-generationspaceobservatoryhassustaineditsfirstnoticeablemicrometeoroidimpactlessthansixmonthsafterlaunch,buttheagencyisn’ttooconcerned.
TheJamesWebbSpaceTelescope,alsoknownasWebborJWST,launchedonDec.25,2021.Ithasspenttheinterveningmonthstrekkingouttoitsdeep-spacepostandpreparingforscienceobservations,acomplicatedprocessthathasgoneremarkablysmoothly;recently,NASAsaiditexpectstounveilthefirstscience-qualityimagesfromthetelescopeonJuly12.
Now,theagencyannouncedonWednesday(June8)thattheobservatoryhasexperienceditsfirstfewimpactsfromtinypiecesofspacedebriscalledmicrometeoroids.Butdon’tpanic:Neithertheobservatory’sschedulenoritsscientificlegacyisexpectedtosuffer.
“WithWebb’smirrorsexposedtospace,weexpectedthatoccasionalmicrometeoroidimpactswouldgracefullydegradetelescopeperformanceovertime,”LeeFeinberg,WebbopticaltelescopeelementmanageratNASA’sGoddardSpaceFlightCenterinMaryland,saidinthestatement.“Sincelaunch,wehavehadfoursmallermeasurablemicrometeoroidstrikesthatwereconsistentwithexpectations,andthisonemorerecentlythatislargerthanourdegradationpredictionsassumed.”
ThemostseriousoftheimpactsoccurredbetweenMay23andMay25andaffectedtheC3segmentofthe18-piecegold-platedhexagonalprimarymirror,accordingtothestatement.
Allspacecraftareexpectedtoexperienceanddesignedtowithstandmicrometeoroidimpacts,andJWSTisnodifferent.Theobservatory’sengineersevensubjectedmirrorsamplestorealimpactstounderstandhowsucheventsmightaffectthemission’sscience.
However,therecentimpactwaslargerthanthosethatmissionpersonnelhadmodeledorcouldtestontheground,accordingtothestatement.
Despitetheimpactcomingsoearlyintheobservatory’stenure,NASAofficialsareconfidentthatthe$10billiontelescopewillstillperformadequately.
“WealwaysknewthatWebbwouldhavetoweatherthespaceenvironment,whichincludesharshultravioletlightandchargedparticlesfromthesun,cosmicraysfromexoticsourcesinthegalaxy,andoccasionalstrikesbymicrometeoroidswithinoursolarsystem,”PaulGeithner,technicaldeputyprojectmanageratNASAGoddard,saidinthestatement.“WedesignedandbuiltWebbwithperformancemargin—optical,thermal,electrical,mechanical—toensureitcanperformitsambitioussciencemissionevenaftermanyyearsinspace.”
Inaddition,JWSTlaunchedwithitsopticsinevenbettershapethantheagencybargainedfor,officialsnotedinthestatement.
Somemicrometeoroidimpactscanbepredicted,officialswrote.Forexample,whenthespacecraftissettoflythroughknownmeteorshowers,personnelcanmaneuverJWST'sopticalsystemsintosafetyfortheseevents.However,therecentimpactwasnotpartofsuchameteorshowerandthestatementclassifieditas"anunavoidablechanceevent."
Afteranimpactoccurs,engineerscanindividuallyadjustthe18primarymirrorsegmentsontheobservatorytokeepthemirrorasawholefinelytuned.
AstheJWSTteamcontinuestoevaluatetheimpact,NASAisfocusedonbetterunderstandingboththeparticulareventandtheenvironmentthattheobservatorywillexperiencethroughoutitsmission.ThetelescopeisorbitingwhatscientistscalltheEarth-sunLagrangepoint2,locatednearly1millionmiles(1.5millionkilometers)awayfromEarthinthedirectionoppositethesun.
“WewillusethisflightdatatoupdateouranalysisofperformanceovertimeandalsodevelopoperationalapproachestoassurewemaximizetheimagingperformanceofWebbtothebestextentpossibleformanyyearstocome,”Feinbergsaid.