model s pre dicted defo rmations that tra nslate d into r equiri ng the cup/ cone interactio n havin g to drive the  truss structure ba ck into shape. T he lat ch preload al one was insufficient; howe ver, the latch  prelo ad was  sufficie nt in driving the cu p/cone s to a p osition where the remotely actuate d bolt can a cquire the nut.   

The system testing d emonstrated the b olting action was capable of deflecting t he truss ba ck into shape,   he system test utilized the structural test article fo r the S1 truss outfitted with t he SSAS passive interface  cceptance Test  testing consisted of   asurements t  sets (on th e  Rock etdyne Truss Attach ment Sy stem (RTAS ) 

he RTAS is a derivative of the SSAS, developed by Rocketdyne, used to assemble the outboard truss seatin g the cup/co nes and esta blishi ng the re quired bolt preloa d. The te sting f urther demonstrated  that  for worst ca se co ndition s only a fra ction (roug hly 1/ 3) of the bolt prelo ad was need ed to f ully seat the   cup/cone.   

T and a struct ural si mulator for t he S0 truss was built and outfitted with the SSAS Active  component s.  Therm al distortions were  simulated by shims i nserted  into the joints  of the S0 simulator. T he S0 simul ator  was suspen ded an d coun terbala nced. The te sts started with th e S0 sim ulator position ed within the  captu re envel ope.  The test s concluded with all four b olts fully enga ged an d prel oaded (Figu re 9).   

A The a ccepta nce  comp onent testing and v erificatio n of  installatio n by three indep ende nt  method s. The first installatio n  verification was perfo rmed by the  manufa cturing team. The  engine ering  drawings establish ed th e “a s built”  locatio ns on t he active inte rface a s the  “basic” dim ensions, and the location of  the mating p assive interfa ce was give n  a position al toleran ce from these   “basic” dime nsions. The m anufa cturing  team used  lase r tra cker in spection  techni ques to mea sure the active  interface an d verify location on th e  mating pa ssive interface. Enginee ring  verification  consi sted of a hardware  simulat or “fit chec k” to che ck f or  potential inte rferen ces any where in th e  berthin g interface combin ed with digital  measurement s ta ken usi ng  photog ramm etry. The  photogra mmetry  device  uses two cameras to tria ngulate   on a  probe  handl e that has six li ght  emitting diodes and calcul ates the  locatio n of the prob e. Even though the  laser tra cker an d p hotogramm etry  device s are very different t echnologies, me order of 0.1 27 mm (0.0 05”)) of ea ch ot her. Th ese two in depe ndent devices alone verifie d the interfa ce  installatio n accura cy. For hard ware installatio n accura cy the hard ware fit check coul d have bee n  eliminated. T he SSAS has been successfully operated tw ice on orbit to assemb le the truss el ements.    aken by each yiel ded consistent d ata Figure 9.  SSAS Sy stem T est:  Coun terbalance s  are in foreg round, large steel be ams form par t  of the S0 si mulator, aluminum struc ture in  back is S1 Struc tural Te st Articl e  T element s of the ISS. The RTAS is a manually d riven me chanical system. T he RTAS u ses the same  captu re claw mech anism from the SS AS (except without moto rs, an d is driven via the “contin gency”  manual override input), and unique, EVA crew operated, attachment  bolts. Active and passive  comp onents of the RTAS are sho wn in Figures 1 0 and 11. 

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