/JHitchhiker Marman BandInterconnect Linkage GaryR.Slebzak* andGeneBarrett* Abstract TheHitchhiker (HH)projectoffersexperimenters theabilitytoejectsmallsatellites intoorbitfromthe SpaceShuttle's cargobay.Duringlaunchthesatellite issecured totheHHejection systemusinga pyrotechically releaseable marman bandassembly. Duetoanon-flight anomaly, theactuation ofthe marman bandassembly wasexamined usinghighspeedvideo.Thevideoshowed apotential forrecontactofthemarman bandassembly withthesatellite fromrebound effectsbeforethesatellite was sufficiently deployed, thereby creating ahazardous satellite tip-offsituation. Thispaperdescribes howtheenergetic releaseandsubsequent motionoftheassembly iscontrolled through theuseofa clampinterconnect linkagesysteminconjunction withasystemofpulldownsprings. Thelinkage systemwasselected asopposed toamoreconventional "catcher" systemduetohardware specific interfaces andadaptability toexisting bandhardware. Thelinkage system controls thereleasing bandmotionbysupporting anddecoupling thepyrotechnic cuttermassfromtheclampportionofthe assembly, allowing unrestricted motionoftheclamps untilthesystem isinthefullyexpanded condition atwhichpointthelinkage actsasanover-center mechanism inhibiting rebound and collapse oftheassembly backtowardthesatellite. Inaddition, theentireassembly ispulleddown andawayfromthesatellite andseparation planebythepulldownspringsystemthatalsosecures it inthepostdeployconfiguration. Sincetheentireactuation takesplaceinlessthan30milliseconds, successful functional testingofthenewlydeveloped mechanism wasdocumented andverifiedusing high-speed videoat1000frames/second. Introduction TheHitchhiker projectissponsored bytheShuttleSmallPayloads Project(SSPP) atGoddard Space FlightCenter(GSFC). TheSSPPhasbeenproviding thetechnology andhardware forejecting small satellites intoorbitusingtheSpaceShuttleasaplatform sincethemid1980's.Thisservicebegan withtheNUSAT satellite in1985aspartoftheGetAwaySpecial(GAS)program. NUSAT became thefirstsatellite tobeejectedfromashuttlecarriedGAScanister usingtheGASEjection System, whichlaterevolved intotheHitchhiker Ejection System (HES).Thelatestseriesofsatellite deployments during1998-1999 hasusedacombination oftheHESandthemoreversatile Pallet Ejection System (PES).Itwasduringoneofthesedeployments, MightySat-01 onSTS-88 in December of1998thatstandard orbitervideotakenduringthesatellite ejection alsodetected debris apparently generated duringthedeployment. Itwasdetermined thatthedebriswas,infact,oneof thecomponents oftheejection systemandthatprompted anextensive investigation intothecause oftheanomaly. Theinvestigation provedtobebotheducational andenlightening. Thecauseofthe debriswasnotthatdramatic andwastracedtoaworkmanship issue.However, theinvestigation furtherrevealed deficiencies intheejection systemconfiguration onlydetectable bytheuseofhighspeedphotography. TheHitchhiker (HH)marman bandinterconnect linkage isthedesign improvement developed tocorrecttheinherent deficiencies discovered intheejection system marman bandusedinboththeHESandPES. Ejection System Background TheSSPPejection systems (Figure1,PESshown) aresimilarindesignandusethesamebasic technique fordeploying satellites. Essentially, thesatellite isplacedontoaspring-loaded pushplate, whichiscompressed andsecured totheejection systembaseusingamarman bandclampassembly (Figure2).Themarman bandassembly wasdeveloped intheearly1970'sbyRockwell fordeploying satellites fromDeltarocketsandthedesignhasbeenusedwithoutchange. Theassembly consists of twohalvesofthemarman band,whichclampthesatellite andbasetogether usingseparation bolts. Thehalvesarealsoconnected toeachotherbymeansofleafsprings, whichassistinband separation andkeepthereleased bandasasingleassembly following deployment. Thereleased SwalesAerospace, Beltsville, MD Proceedings ofthe35thAerospace Mechanisms Symposium, AmesResearch Center,May9-11,2001 265