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,pjakobse@rssd.esa.int).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