Asteroid Sampling Mechanism forMUSES-C KenHiguchr, Jun'ichiro Kawaguchi*, AkiraFujiwara*, Toshiaki Okudaira**, andSatoruYajima+ Abstract Anasteroid mission oftheInstitute ofSpaceandAstronautical Science (ISAS)isdevoted toacquiring a sample onanasteroid surface andthenreturning ittotheearth.Itssampling system, named"sampler", is aunique ideaandisasubsystem oftheMUSES-C spacecraft. Sampler hasmanyengineering challenges, butwiththefinalpurpose ofthesampling beingscientific, thesampler structures and mechanisms havebeendeveloped underthescientific requirements andrestrictions. Thesample should notbecontaminated byartificial matterornatural matteroriginated ontheearth(:luringmanufacturing, integration, cruising, sampling, reentry, andrecovery. Thesampler hasthreeprojectors, andeach projector firesaprojectile inordertofragment anasteroid surface intosmallpieces. Thesample isstored inacontainer anditisretrieved usingareentrycapsule. Thesampler involves manylinearandrotational slidingmechanisms, andtheyshouldworkinadustyorcrunchy environment afteralongcruiseperiodin aspaceenvironment. Thefunction ofeachmechanism hasbeenverified bygroundtests.Slidingtestsin asandyandcrunchy environment verified thefunction andthelimitations ofthesampler, andhighfrequency shocktestsverified thatthesample container isairtightduringthereentry. Introduction Asampling system onanasteroid surface wasdeveloped tomeetengineering andscientific requirements afteralongcruiseinspaceenvironment. Inordernottoreduce thescientific valueofthesample, the structures andmechanisms ofthesampler should meetmanyscientific requirements suchas contamination, sealing, anddismantle process. Popular spacelubricants arenotwelcomed, andhardanodized aluminum coatedbypolytetrafluoroethylene (PTFE) isusedatthesurface ofslidingparts.The sampling mechanism istoworkafteratwo-year cruiseinspace,andthesample inthereentrycapsule is toberetrieved afterfour-year cruise. However, thesampling mechanism needstoworkinapresumably crunchy environment, because theprojector makes dust,sandandfragments ofrocksflyup.The functions ofslidingpartsincrunchy environments needtobeverified bytests.Themechanisms are considered tobeassimpleaspossible; noelectromagnetic motorisused.Projectors tomakesamples andamovable horntocollectsamples areadaptive tosometopographical andphysical uncertainty ofthe environment onanasteroid. MUSES-C standsforaseriesofmissions performed bytheSpaceEngineering Spacecraft launched by MUrocketofISAS,andtheCmeansthethirdmission ofthisseries.Theprimary goaloftheMUSES-C mission istoacquire andverifytechnology necessary toretrieve samples andtobringbackthemtothe earth.Thespacecraft usesasolar-powered electrical propulsion system, andanautonomous navigation andguidance toasmalltargetindeepspace.Thespacecraft collects asample duringthetouch-and-go ontheasteroid surface. Asmallrobotlanderwillbealsodelivered tothesurface. Inthefinalphase,a smallreentry capsule conducts thereentry flightfromtheinterplanetary earthreturntrajectory. The scientific returnsarepromising evenifthesample amount isverysmall. Thedesignconditions ofthesampler arediscussed, thenthesampling sequence isillustrated, andthe operational testsarepresented. *TheInstitute ofSpaceandAstronautical Science, Sagamihara, Japan **NECTOSHIBA SpaceSystems, Yokohama, Japan ÷Sumitomo HeavyIndustries, Niihama, Japan Proceedings ofthe36thAerospace Mechanisms Symposium, GlennResearch Center,May15-17,2002 NASA/C P--2002-211506 1