WebbUpdateSpring2011
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TheJWSTIntegratedScienceInstrumentModule(ISIM)isthesciencepayloadoftheJWST(seeGreenhouseetal,2010ProcSPIE,7131).Alongwiththetelescopeandspacecraft,theISIMisoneofthreeelementsthatcomprisetheJWSTspacevehicle.At1400kg,itmakesupapproximately20%oftheobservatorymass.Inordertomaximizeefficiencywithrespecttomass,power,andnonrecurringengineeringcost,thefourJWSTscienceinstrumentsarenotdesignedastraditionalstand‐alonesystems;rather,theISIMprovidesninekeysubsystemsthataresharedbyeachofthescienceinstruments(seeFigureonp.5).Theseare:[1]opticalmeteringstructure[2]ISIMElectronicsCompartment(IEC)[3]harnessradiator(HR)[4]ISIMCommandandDataHandlingSystem(ICDH)[5]ISIMRemoteServicesUnit(IRSU)[6]electricalharnesssystem[7]thermalcontrolsystem(TCS)[8]flightsoftwaresystem(FSW)[9]on‐boardscriptsystem(OSS).
TheflightmodelbuildoftheISIMsystemisunderwaywithallscienceinstrumentsbeginningflightmodelcryogenicperformancetestingthisyear.
AlloftheabovesubsystemsareonschedulefordeliverytoISIMI&Tduring2011.TheISIMflightstructurehascompletedcryogenicperformancetestingandwillcompletemodalandambientstrengthprooftestduringApril.TheflightIRSUhasbeendelivered,andtheICHD,IEC,HR,andTCSarecurrentlyinintegration.TheFSWisinamaturebuildstateincludingintegrationofallscienceinstrumentapplications.TheOSScompleteditscriticaldesignreviewduringDecemberof2010andisonscheduletosupportISIMI&T.DevelopmentofgroundsupportequipmentforISIMsystem‐levelI&Tisalsoonschedule.TheObservatorytelescopesimulator(OSIM)hascompletedambienttestingandwillbegincryogenictestinginduringMay.
TheJWSTIntegratedScienceInstrumentModule(ISIM)continuesprogresstowarddelivy
WebbUpdateSpring2011
TheJWSTIntegratedScienceInstrumentModule(ISIM)continuesprogresstowarddeliverybyMattGreenhouse
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PhilSabelhaus,theformerprojectmanager,hastransitionedtoanothermissionatGSFC,theLandsatDataContinuityMission,astheprojectmanagerwherehewillleadthatteamtoalaunchin2012.WewishPhilthebestofluckandthankhimforhis8yearsofleadershipontheJWSTprogram.PhilsawtheprojectthroughitschallengingdefinitionandtechnologydevelopmentphasesandhelpedNASAcreatethesoundhardwarebasiswearenowseeingcometofruition.
FollowingtheOctober2010receiptoftheCongressionally
requestedIndependentComprehensiveReviewPanel
(ICRP)report,NASAbegantomakechangestoitsJWST
Programtoaddressproblemsidentifiedinthereport.
ProgramandProjectmanagementofficesatHQandGSFC
respectivelywereelevatedinthemanagementreporting
chain.TheJWSTProgramOfficeheadedbyRickHowardat
HQnowreportstotheNASAAssociateAdministrator(C.
Scolese).AtGSFC,newProjectManagerBillOchsreports
totheCenterDirector(R.Strain).Bothofthesemoveswill
servetobringJWSTprogressandissuestoagencyupper
managementinaregularandrapidfashion.Itclearly
elevatesJWSTtoanagencymatter,notjustaGSFCor
AstrophysicsDivisionone.
Thelaunchdateandassociatedfundingrecommendations
containedwithintheICRPreportwereconsideredinthe
programreplanningeffort,butinthistimeofgovernment‐
widefiscalchallenges,foundtobeunsustainable.Overthe
ensuingmonthstheprogramhasworkedwithits
contractorteamstodevelopanewbudgetandschedule
thatwillgothroughformalagencyapprovalprocesses
duringtheSpringandSummer.Thisnewplanwillbe
coordinatedwiththeOfficeofScienceandTechnology
Policy,theOfficeofManagementandBudget,Congress
andtheJWSTinternationalpartners.
ToaddresstheICRPconcernaboutvisibilityofscience
withintheprojectNASAhasaddedexperiencedHubble
SpaceTelescopeProjectScientistforOperationsDr.Mal
NiednertotheJWSTscienceteamastheDeputySenior
ProjectScientist,Technicalandmembersofthisscience
teamparticipateintheweeklydialogbetweentheproject
andGSFCCenterDirectorRobStrain.
Itisimportanttorememberthatduringthisextensive
replanningperiodexcellentprogresshascontinuedwith
JWSTflighthardware.Asthisletter“goestoprint”weare
preparingforthefinalcryogenictestingof6primarymirror
segments.Allmirrorsegmentshavecompletedtheir
polishingandmeetthestringentrequirementsneededfor
JWSTscience.ScienceinstrumentswillbearrivingatGSFC
intheSummerandFalltobegintheirintegrationprocesses.
2011willbeadramaticyearforflighthardwaredeliveries
astheprogrampreparestoenterintoitsintegrationphase.
JWSTProgramChangesbyEricSmith
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Webb’sMirror:TheHomeLegbyMarkClampinIntheconstructionofanytelescopecompletingtheopticsisamajormilestone,andtheWebbSpaceTelescopeisnoexception.Withitssegmentedprimary,therearemanymirrorstopolish,atotalof18primarymirrorsegments,asecondarymirror,atertiarymirrorandafinesteeringmirror.Webb’smirrorsareespeciallychallengingsincethemirrorsarepolishedatroomtemperature,buttheiropticalprescriptionhastobecorrectatJWST’soperatingtemperatureof40K.Apolishingtechniqueknownascryo‐polishingisemployedtoaddressthischallenge.Priortothelaststageofmirrorpolishing,asthefigurequalityreaches~150nmRMS,theJWSTprimarymirrorsegmentsareshippedtotheMarshallSpaceFlightCenter(MSFC),sothattheircryo‐distortion,thechangeinshapeasthemirrorcoolsfromambientto40K,canbemeasured.Figure1showssixJWSTprimarymirrorsegmentsbeinginsertedintotheMSFCtestchamberfortheircryo‐distortiontesting.Onceamirror’scryo‐distortionhas
beenmeasured,afinalpolishingprescriptioncanbegenerated,sothateachprimarymirrorsegmentwillmeetitsrequiredsurfacefigureerrorof24.5nmRMSthenexttimeitismeasuredat40K.Followingthecompletionofmirrorpolishing,eachsegmentisgoldcoatedandthenundergoesacceptancetesting,whichcomprises3‐axisvibrationfollowedbyafinalcryogenictesttoverifyitsfigure.Theprogramismakingexcellentprogressincompletingflightprimarymirrorsegments.Todate,ninesegmentshavecompletedpolishing,witheightofthesemirrorsgold‐coated.Inaddition,boththetertiaryandfinesteeringmirrorshavebeencompleted.Onthecurrentscheduleitisplannedtocompletepolishingoftheprimarymirrorsegmentsbyyear’send.ThefirstprimarymirrorsegmentassemblytocompleteacceptancetestingisshowninFigure3andmeetstherequirementsforitsopticalspecification.Finalacceptancecryo‐testingofthenextfiveflightmirrorsisscheduledtobegininApril2011.
Above: JWST’s optical train is rapidly being populated with completed mirrors. To date nine primary mirror segments have been gold-coated, including the flight spare EDU mirror. The flight tertiary and fine steering mirrors have also completed polishing and received their gold coating.
Left: Cryo-testing at the MSFC. Six flight mirrors stand ready on the test fixture prior to insertion into the cryogenic test chamber (top). The Engineering Design Unit (EDU) mirror assembly recently completed all of its acceptance tests, including the final cryogenic test. The mirror surface figure error of 24.4 nm RMS meets the requirement of 25.8 nm (bottom).
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WouldyoulikeacolloquiumatyouruniversityonJWST?Howaboutatalkataconferenceyouareorganizing?TheseJWSTscientistsarewillingtogiveatalk.AllexpenseswillbepaidbytheJWSTprojectfortalksintheUS;talksinothercountriescanalsobearranged.Toarrangeatalk,pleaseemailcontactswg@jwst.nasa.govorcontactthespeakerdirectly.ForEuropeanuniversitiesandinstitutionsinterestedininvitingspeakerstogivetalkscoveringthefullrangeofscientifictopicsaddressedbyJWST,pleasecontactPeterJakobsen(ESAJWSTProjectScientist,ESTEC,[email protected]).ThespeakersarealsoavailabletogiveJWSTMissionOverviewtalksandtalksatthegeneralpubliclevel.Imagecreditpage1:BobbyBradley
• MarkClampin,GSFC,"ExoplanetswithJWST"• ReneDoyon,UniversitedeMontreal,"JWSTTunableFilter
Science"• JonathanGardner,GSFC,"JWSTandGalaxyEvolution"• MattGreenhouse,GSFC,"JWSTMissionOverviewand
Status"• HeidiHammel,SpaceScienceInstitute,"Planetary
ExplorationwithJWST"• JohnHutchings,DAO,"JWST’sGuiderandTunableFilter
Imager"• JonathanLunine,UniversityofArizona&UniversityofRome,
"JWST,ExoplanetsandtheSolarSystem"• JohnMather,GSFC,"JWSTMissionOverviewandStatus"• BernieRauscher,GSFC,“JWSTandit'sHAWAII‐2RGand
SIDECARASICDetectorSystems”• GeorgeRieke,UniversityofArizona,"DebrisDisksandthe
EvolutionofPlanetarySystems"or“ThePlaceofJWSTinthegrowthofInfraredAstronomy”
• MarciaRieke,UniversityofArizona,"NIRCamforJWST:ExoplanetstoDeepSurveys"
• JaneRigby,GSFC,“GravitationallyLensedGalaxiesandJWST”or“AGNandJWST”
• GeorgeSonneborn,GSFC,"ImagingandSpectroscopywithJWST"
• MassimoStiavelli,STScI,"StudyingthefirstgalaxiesandreionizationwithJWST"
• AmberStraughn,GSFC,“JWSTandGalaxyAssembly”• RogierWindhorst,ArizonaStateUniversity,"JWSTand
Reionization"or"JWSTandSupermassiveBlackHoleGrowth”
WebbUpdateSpring2011AmberStraughn,Editor
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