3.Ifthecouplingonthespindleisstuck,onlyonepipecanbeusedandthelengthofthepipelimitsthe possiblesamplingdepth. 4.Incasethetoolgetsstuckonthepipe,onlythisonepipeandthisonetoolcanbeused,buttherover maintainsitsmovingcapability. Development andprototyping Theentiredrillingsystem wasdesigned withIDEAS3Dmodeling software, whichwasofagreathelp whenfittingallmoving partsandcomponents insidethelimitedvolume. Atcertain stageofdevelopment andmodeling itwasdecided thatinstead ofcontinued visualmodeling ahardware-model wouldprovide a moreconcrete playground andfasterprogress. The3Dmodelwastranslated intoanSTL-file thatwas usedtoproduce aplasticmodelofthemostimportant parts(roughly 30pieces) withfuseddeposition modeling (FDM)method. Thisplasticprototype wasfittedwithallmechanical motions, notelectrically driventhough, whichclearlyexposed potential interference andtightplaces. Someofthepartplacement, likethemicroswitches, wasdonefirstwiththeplasticmodelandonlythen transferred tothecomputer model.Alsoallofthemountings andscrewsweredesigned withtheprototype first.Thisapproach appears tobeveryfastandefficient. However, acoupleofthingsthatshould have beendoneinthistimewerelefttowaitforthefinalmodel,whichlaterturnedouttobeamistake. Details likethepipeholder(thatprevents apipefromdropping fromthecarousel intothedrilling hole),tool cleaning brushes andcomplete wiringdesign, turnedouttobeextremely difficult andtookalotoftimeat thestagewheretherewasnotthetimereserved. Ingeneral detailslikethese,andalsoallnewfeatures, should beprototyped andtestedsimultaneously duringdesigning toavoidsurprises inassembly and integration phase. Testing Thedrillperformance istobetestedonaset-upconstructed ofaplatform anda2-m-long transparent plastictube.Thesoilsample tobedrilledintoisprepared intothetubeandthedrillingsystem sitsonthe platform, mounted eitheronaseparate jigorontherovingvehicle. Drilling speedandthrustare measured withthedrill'sowninstrumentation, whiletorque-measuring system ismounted tothejig.The sample tobeprepared willconsist ofdrysandwithvarying grainsizeandcompactness, addedwith occasional boulders ofmarble, limestoneandsandstone,Theaimofthetestsistodetermine drilling speed, powerandforces, andtodemonstrate capability toobtainsamples fromthedesired depthand fromthedesired materials. Vacuum compatibility andqualification forspace Thisdeviceismerelyanadvanced proof-of-principle model;operations ofwhichstillrequiredevelopment forbetterefficiency andreliability. Themodel isconstructed ofcommercial andself-manufactured components, butitsoperation doesnotrelyonanyspecial partsormaterials thatcouldnotbemade space-qualified. Onamechanical pointofview,thedesign lackslaunch locksthatmightbenecessary foraspace instrument, andmasscanstillbereduced byanother -0.5kgwithoptimized structural design. Effectsof thermal expansion, thermal balance, andprotection against dustmustbestudied carefully toguarantee operation ofthedrillinspaceenvironment. Lessons Learned PipeCouplin.qs Round-edged trihedron designfamiliar fromrobotwrist/tool interfaces appears tosuitwellforautomated connections between parts.Asplitring,oraC-ring,forsecuring ofthecoupling, although simpleindesign andeasytouse,hassomedisadvantages relatedtoclinging andpossibly toringorientation. 197