CRISPandtheCONTOUR Mission TheCONTOUR spacecraft willflywithin100Kmofthreecometnuclei:Enckein2003,SchwassmannWachmann-3 in2006,andd'Arrest in2008.Theprimary science goalsofCONTOUR are: 1.Toassesthediversity ofcomets 2.Tostudytheprocess bywhichcometnucleiworkinunprecedented detail 3.Toassesforthefirsttimethedifferences between KuiperBeltandOortCloudcomets Shortperiodcomets areremnants ofsolarsystem formation thatoriginated intheKuiper Beltoficy asteroids beyond theorbitofNeptune. Longperiodcomets comefromtheOortCloudthatextends upto onelightyearawayandmaybelessprimitive. CONTOUR's science payload willconsist offour instruments performing thefollowing functions: Highresolution imaging, spectral mapping, impactdust analysis, neutralgasandionspectrometry. CONTOUR expects toproduce thebest-ever images ofcomet nucleiwithaminimum resolution of4m,25xbetterthanGiottos famous viewofCometHalley's nucleus, andthebest-ever compositional analysis ofcometdustandgasinthevicinity ofthenucleus. CRISP, Figure1,isintended totrackthenucleus ofthecometasCONTOUR fliesbyproducing highresolution colorimages andspectroscopy todetermine composition ofthenucleus andprocesses thatshapethe surface. Deployment Environment Thecoverisexpected tobedeployed approximately onetotwomonths afterlaunch. Thespacecraft will reduce itsspin-rate forcoverdeployment andinstrument functional check. Thenominal operating temperature ofthetracking mirrormechanism, coverandrelease mechanism isexpected tobebetween -40°and-60°C. Lubrication Adryfilmlubricant wasdesired forallmoving surfaces because ofthelowtemperatures. Asurveyofthe literature leadustobelieve thatsputtered molybdenum disulfide (MoS2) wastheidealchoice. However, wealsowanted tocompare tungsten disulfide (WS2),assoldbyDicronite andionplatedlead.Samples wereacquired onseveral testspecimens thatweresimilartoourmechanism components. Itbecame immediately obvious thattheDicronite wasvastlysuperior forourrelease mechanism application. Sputtered MoS2 exhibited significantly morestiction andhighercoefficient offrictionatambient conditions whereweexpected todothevastmajority ofourtesting. Theonlydeployment teststhatwereactually conducted invacuum weretosimulate deployment at-60°C.Wealsochosetheionplatedleadover sputtered MoS2 forthetracking mirrorbearings. Thiswasmainlyduetoalackofinformation available in theliterature forWS2orDicronite inthisapplication andthationplatedleadhadpreviously beenused withgoodresultsatJHU/APL inanidentical motor/encoder. Material Selection TheCRISP instrument isfairlylarge,683Hx1267W x502Dmmand22.6kg,andwasverymass constrained. Theupperandlowerhousings forming theprimary structure oftheinstrument, thetracking mirrorassembly base,andthestarcamera brackets, Figure1,wereallfabricated fromsolidbilletsof magnesium ZK60A-T5. Thetwo-sided tracking mirror,Figure 14,itselfwasfabricated fromaluminum 6061-T6. Titanium 6AI4Vwasusedforthemotor/encoder housing. Analysis indicated thatallofthe tracking mirrorassembly brackets, bearing housings anddiaphragm wererequired tobefabricated from Ti6AI4V inordertomatchthemotor/encoder housing. Interfacing materials withdrastically different coefficients ofthermal expansion (CTEs) required significant amounts offiniteelement analysis and attention todetail.The-60°Cenvironment dictated theuseoftitanium fasteners tomatetotitanium parts sothatfastener preload wouldnotbelost.Dissimilar materials wereusedtoadvantage intherelease mechanism, wherethelargerCTEmaterial, stainless, running insidethelowerCTEmaterial, titanium, suchthatclearance tolerances wouldneverbelost.Ambient temperatures, wheremosttestingoccurred, wasourworsthotcase. NASA/CP--2002-211506 64