spacecraft. Eachfiringofprojectoristriggeredbythedetectionoftouchdown ontheasteroidsurface.The projectorshouldbedesignedtominimizethecontamination tothesamplefromcombustion gases. Samplingsequenceshouldbeexecutable safely.Forsafety,thesamplersubsystem shouldmatchthe othersubsystems ofthespacecraftandmissionsuchasAOCS,RCS,reentrycapsule,structures,and thermalsystems.Samplerhorndoesnotinterferewithanyrangeofvisionoftheotherinstruments for navigation andscience.High-speed fragmentsandreflectedprojectilemaynotdamagespacecraft includinglargesolararraypanels.Structuresandmechanisms areadaptivetoanexpectedslopeand roughnessofthesurface,evenifthespacecraftremainsthetransversal velocity.Samplingmechanism is toworkaftertwo-yearcruiseinspaceenvironment. Samplingactionswillbecarriedoutinpresumably crunchyenvironment withdust,sand,andfragment.Thetransportation systemofthecatcherfromthe ductpositiontothecontainerinthereentrycapsuledoesnotbecomeacauseofdisturbances atthe separationofthereentrycapsulefromthespacecraft. Everymechanism andsequenceworkssteadilyin theasteroidenvironment ofhighvacuumandmicro-gravity. Thebesteffortshouldbemadesothatthe occurrence ofamalfunction insamplingsequencecanminimizetheeffectsontherestofthemission. Thesamplersystemshouldbelightweightstructure,consumeasmallamountofelectricpower,stays withinthespacecraft, staywithintheallowedenvelopeatlaunching,andwithstandthemechanical and thermalenvironment ofthelaunching,cruising,andsamplingphases.Thesampleinthereentrycapsule shouldberecoveredwithoutlossofscientificmeritinafour-yearcruiseafterlaunch.Theclearanceof everyslidingpartmustbeverifiedbyslidingtests.Adesignofsamplingsystemmustpermitsome uncertainty ofenvironments ontheasteroidsuchastemperature, gravitation, hardness,roughness, slope, andconstituent ofthesurface. Structures andMechanisms Theoutlineofsampling isillustrated inFigure1.Aprojectile of5xl0-3kgneedstobefiredwithvelocity of 300m/stofragment thetargetsurface. Theprojector method maybeabletomeetthevariation of conditions ofthesurface, whichmaybemadeofsolidmetal,rock,orsand.Sample fragments, andalso projectiles bysomechance, arecaught inthecatcher. Theinsidevolume isabout60x10-6m3.The fragments ofdifferent sampling pointsonthesurface arestoredinapartitioned catcher. Thestructure of thewholesampler isshowninFigure2.Itconsists oftwomajorportions, ahornmechanism assembly andasampling mechanism assembly. Figure3showsthecomponents. Thehorn,whichisadeployable structure, isusefulnotonlybecause itiscompact atlaunching butalsobecause itworksasapartof touchdown sensor repeatedly, andbecause itisadaptive tothevariation intheslopeandroughness of asteroid surface. However, thespacecraft remains thetransversal velocity. Theextended lengthofthe hornis1mfromthebottomofspacecraft. Usually, spacemechanisms workunderahigh-vacuum andcleanenvironment soonafterlaunch. Onthe otherhand,thesampling mechanism needstoworkinapresumably crunchy environment, because the projector maymakehardfragments andthesurface maypossibly besandy.Therefore, thelubrication of themechanism inabadenvironment isveryimportant. However, duetorequirements ofscientific analyses, typicalsolidlubricants suchasmolybdenum disulfide, gold,silver,andlead,arenotpermitted wheresamples mayconfront orpassby.Hard-anodized aluminum coatedbyPTFE,whichdoesnothave afatalinfluence onthesamples, isusedonthesurface ofsliding parts.Thesurface ofaluminum structural elements thatcontact thesample iscoated withpurified aluminum, according toscientific requirements. Allofthemechanisms workbyspringforcesforsimplicity. Noelectromagnetic motorisused.Thespring forcesarereleased byshapememory alloy(SMA)drivenactuators, anon-explosive actuator (NEA),and apyrotechnic wirecutter.Themagnitude ofspringforcesisrestricted, because thespringforcesandthe actuation shockaredirectly relatedtotheweightofthestructures andmechanisms ofsampler, although themechanisms needenough forcetoworkinacrunchy environment afterlongexposure duration in spaceenvironments. Theweightofsampler isshowninTable1. Thecatcher isstoredinacontainer inthereentrycapsule atthefinalphaseofsampling. Thecontainer shouldbekeptairtightagainst theshockenvironments duringreentryandlanding. NASA/C P--2002-211506 3