STS-68 Space Shuttle Mission Report

8/7/2019 STS-68 Space Shuttle Mission Report

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NASA-CR-199570NST4

(NASA-CR-199570) STS-68 SPACEN96-11500SHUTTLE MISSION REPORT (LockheedEngineering and Sciences Co.) 58 p UnclasG3/16 0066431

January 1995

L I B R A R Y C 0 1FEB

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The STS -68 Space Shuttle Mission Report was prepared frominputs received from the O rbiter Project Office as well as otherorganizations. The following personnel may b e con tactedshould quest ions arise conceming the technical content ofth is docum ent .Bobbie Gail SwanOrbi ter a n d s u b s y s t e m s713.483-2528C. A. Snoddy, MSFCMSFC Elements (SRB,205-544-0381RSRM, SSME, ET,SRSS, and MP SG. P. Buon i, JSCFlight Integration713-483-0639Manager , and DTO s andD S O sEd J. Jung, Jr . , JSCSRL Payload713-483-1154F. T. B ums, Jr . , JSCF CE and G F E713 .483-1262


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N S T S 0 8 2 94

S T S - 6 8SPACE SHUTTLEMISSION REPORT

by

Rob er t W . - Frfbke,L E S C / F l i g h t Evaluat ionAp p ro ved by

z 5 ^ &14 ^ - : ; ; ^-' z" z ^Bobbie O, % i l Sw anSTS-68 LeadMiss' n valuation Room Managerai4La7 - Da d W. CampM anager , F l igh t E ng ineer ing and Veh ic le M anagement O f f ice, O r b i t e r

I U Brewster H. ShawD i r e c to r , S p a c e S h u t tle O p e r a t io n sP r e p a r e d b yL o c k h e e d E n g i n e er in g a n d S c i e n c e s C o m p a n y

fo rF l ig h t E n g i n e e r in g O f fic eN A T I O N A L A E R O N A U T IC S A N D S P A C E A D M I N I ST R A T IO NL Y N D O N B . J O H N S O N S P A C E C E N T E RH O U S T O N , T E X A S 7 7 0 5 8

January 1 995


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STS-68 Tab le o f ContentsTit leP a a eI N T R O D U C T I O N......................................... 1M I S S I O N S U M M A R Y ...... ................................. 3PAYLO ADS .............................................. 7S P A C E R A D A R L A B O R A T O R Y -2 ....................... 7CH ROMOSOM E AND PLANT CELL DIVISION IN SPACEE X P E R I M E N T .................................. 8C O M M E R C I A L P R O T E I N C R Y S T A L G R O W T H E X P E R I M E N T . 8B I O L O G I C A L R E S E A R C H I N C A N I S T E R S E X P E R I M E N T . .... 9C O S M I C R A D I A T I O N E F F E C T S A N D A C T I V A T I O NM O N I T O R E X P E R IM E N T .......................... 9

M I L IT A R Y A P P L I C A T I O N S I N S H I P T R A C K S E X P E R I M E N T .. 9G E T AW AY S P EC I AL S ................................. 9VEHICLE P E R F O R M A N C E .................................. 1 1S O L ID R O C K E T B O O S T E R ............................. 1 1L a u n c h Abort .................................. 11Launch ........................................ 11REDESIGNED SOLID ROCKET MOTOR ................... 12L a u n c h A b o r t.................................. 12L a u n c h ....................................... 12E X T E R N A L T A N K ..................................... 13L a u n c h A b o r t ................................... 13L a u n c h ........................................ 14SPACE SHUTTLE MAIN ENGINES ........................ 15L a u n c h A b o r t ................................... 15L a u n c h ........................................ 15SHUTTLE RANGE SAFETY SYSTEM ...................... 16L a u n cgh A b o r t ................................... 18.L a u n c h...................................... 17O R B I T E R S U B S Y ST E M S ............................... 17Main P r o p u l s i o n System .......................... 17R e a c t io n C o n t r o l S u b s y s te m ...................... 18O rbi ta l M gneuver ing Sub sys tem .................... 19P o w e r R e a c t a n t S t r o r a ct e a n d D i st r ib u t i o n S u b s y s t e m . . 2 0F u e l C e l l P o w e r p l a n t S u b s y s t e m ................... 20

Au xi li ary Power Unit Subsystem .................... 21H y d r a u l ic s /W a t e r S p r a y B o i le r S u b s y s te m . , .......... 22E l ec tr ica l Power D i str ibut i on and C ontro l Subsystem .. 23E n v i ro n m e n t a l C o n t r o l a n d L i fe S U R R a r t S u b s y st e m . . 23A i r lo ck S u p p o r t S y s t em .......................... 24S m o k e D e t e c ti o n a n d F i r e S u o o r e s s io n S u b s y s t e m . .. . 24


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S T S - 6 8 T a b le o f C o n t e n tsT i t l ePa eA v io n i cs a n d S o f t w a r e S u p p o rt System ............. 2 5Di sp l aXs an dC o n t r o ls S u b s y s te m .................. 26Com municat ions and Tra ck ing Subsystems ......... 2 6O p e r a t io n a l I n s t ru m e n t a t io n / M o d u la rAuxi l iary Data System ........................ 2 7St ruct ure s a n d M e ch a n ica l Sub s sy t e m s ............. 2 8I n t e a ra t e d Ae rod yna mics . H e a t ing a nd Th e rma lIn ter faces ................................... 2 8Thermal C o n t r o l S u b s y s t e m ....................... 2 9A e r o t h e r m o d y n a m i c s ............................. 2 9 +T h e r m a l P r o t e c ti o n Subsystem ..................... 30R E M O T E M A N IP U L A T O R S Y S T E M ..................... 32F L IG H T C R E W E Q U I P M E N T IG O V E R N M E N T F U R N I S HE DE Q U I P M E N T ................................ 33C A R G O I N T E G R A T I O N ....................................... 35D E V E L O P M E N T T E S T O B J E C T I VE S I D E T A IL E D S U P P L E M E N T A R YO B J E C T I V E S ................................36D E V E L O P M E N T T E S T O B J E C T I VE S ...................... 36D E T A I L E D S U P P L E M E N T A R Y O B J E C T I V E S ................ 38P H O T O G R A P H Y A N D TE L E 'V ' IS ION AN AL Y SIS ................... 4 0L A U N C H P H O T O G R A P H Y A N D V I D E O D A T A A N A L Y S I S ...... 4 0O N - O R B I T P H O T O G R A P H Y AN D V I D E O D A T A A N A L Y S I S .... 4 0L A N D IN G P H O T O G R A P H Y A N D V I D E O D A T A A N A L Y S I S . .... 4 1

List of T a b l e sT A B L E I - S T S - 68 S E Q U E N C E O F E V E N T S ..................... 4 2T A B L E I I - S T S - 6 8 O R B IT E R P R O B LE M T R A C K I N G L IS T .. .. .. .. .. 4 5TABLE III - STS-68 GFE PROBLEM TRACKING LIST .............. 48T A B L E IV - M S F C E L E M E N T S P R O B L E M T R A C K IN G L I S T . ........ 5 0

A p p en dix esA - D O C U M E N T S O U R C E S .................................. A-1B - A C R O N Y M S A N D A B BR E V I AT IO N S ........................ B-1


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T he ST S -66 Space Shu t t le Program M iss ion Repo r t summ ar izes t he Pay loadact ivit ies as wel l as the O rbi te r , Externa l Tank (E T) , So l id Rocket Booster (SR B) ,Redes igned So l id Rocke t Mo to r (RSR M ) , and the Space Shu t t l e main eng ine(SSM E) system s per formanc e dur ing the s ix ty- f i f th f l ight of the Space S hut t leProgram and the seventh f l ight of the Orbi ter vehicle Ende avour (O V-105) . Inaddi t ion to the Orbi ter , the f light vehicle consis ted of an ET that was d esignatedE T m 65 ; th ree SSM Es tha t we re des igna ted a s s e r ia l numb ers 2028 , 2033 , and 202 6i n pos i ti ons 1 , 2 , and 3 , r e spec t ive ly ; and two SRB s tha t were des igna ted BI -067 .T he RS RM 's tha t were ins t a ll ed in each SRB were des igna ted as 36OW 040A fo r thel e f t SRB , and 36OW 040B for the r igh t SRB .T his ST S-68 Space Shu t t le P rogram M iss ion R epor t f u lf i ll s t he Space S hu t t leProgram r equ i remen t as docum ented in NST S 07700 , Volume Vi ll , Append ix E . T herequireme nt that is s ta ted in that doour tent i s that each. m ajor organizat ional e lemen tsuppor t ing the Program wi l l repor t the resul ts of thei r hardware (and sof twa re)evaluat ion and m ission pe r formance, p lus ident i fy a l l re la ted in- f light anom al ies .The pr im ary ob jec t ive of th i s f l igh t was to successfu l ly perform the opera t ions of theSpace R adar Labora to ry -2 (SRL -2) . T he seconda ry ob j ec t ives o f t he f l igh t were toper fo rm the opera t ions o f t he Chrom osome and P lan t Ce l l D iv i s ion in Space(CH ROM EX ) , t h e Co m merc i al P ro t ei n Crys t a l Gro wt h (CPC G) , t h e B i o lo g ica lResearch in Can is ters (BRIO ) , the Cosm ic Radia t ion Effec ts and Ac t iva t ion Moni tor( C RE AM ), the M i li ta ry A pp l ica t ion o f Sh ip Tracks ( MA ST) , and f iv e Ge t -Aw ay Spec ia l(GA S) pay loads .T h e S T S - 5-8 miss ion was p l anned wi th a 10-day dura t ion p lus 1 ex tens ion day p lus2 con t ingency days , wh ich were ava iW,la for weather avoidance or O rbi tercont ingency op e ra t ions . The sequence of event s for the ST S-68 m is sion i s show n inTable 1 , and the Orb i te r Pro jec t Off ice Problem Tracking Lis t is shown in Tab le I I .The off ic ia l Governm ent Furn ished Equipment (GFE ) Problem Tracking Lis t i s shownin Table I II , and the M arshal l Space F l ight C enter (MSF C) Problem T racking List isshow n in Table IV. In addi t ion , the In tegrat ion and P ayload in- f l ight anom al ies arer e fe renced in appl icab le s ec t ions of the r epot . App endix A l is t s the sources of d a ta ,both form al and informal , that were used in the preparat ion of th is repor t . App endixB p rov ides the de f in it ion o f ac ronyms and abb rev ia t ions used in th is docum ent . Al lt imes a r e g iven in Greenw ich mean t ime (G .m. t .) a s we l l a s m i ss ion e l apsed t ime(MET) .The six-pe r son c r ew fo r ST S-6B cons i s t ed o f Michae l A . B aker , Cap t ., U . S . N avy ,Co mm ander , Terrence W . Wilcu tt , Major , U. S. M arine Corps , P i lo t; Steven L . Smi th ,M ission Spe cial is t 1; Daniel W. Bu rsch, Cdr . , U. S. Navy , M iss ion Sp ec ia li s t 2 ; Pe t e rJ . K. W isoff , Ph.D . , M ission Special i s t 3; Thom as D. Jones, Ph. D. , Pay load


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Co m ma nder and M iss ion Spe c ia li s t 4 . ST S-68 w as the th i rd space f l i gh t fo r t heC om m ander ; the second f l ight for M ission Special is t 2 , M ission Special i s t 3 , andM ission S pecial i st 4; and the f i rs t space f l ight for the Pi lo t and M ission Sp ecial is t 1 .

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MISSION S U M M A R Y

T he f i r st l aunch a t tempt o f t he ST S -68 miss ion on A ugus t 18 , 1994 , ended a t230:10:53:58 .157 G.m . t . [1 .8 seconds pr ior to Sol id Rocket B ooster ;SRB ) ign it ion],when the SSM E s w ere shu t down. SSM E 3 h igh p ressu re ox id ize r t u rb ine (HP OT )d i scharge t empera tu re A exceeded the Launch Com mi t Cr i t e ri a (LCC ) r ed line o f1560 R. As a resul t , the vehicle was re turned to the Vehicle Assem bly Bui lding(VAB ) and a l l t h r ee SSME s were r ep laced .T he second l aunch a t t empt o f t he ST S-68 m iss ion r esu l ted in an on - t ime l aunch a t273 :11 :16 :00 .011 G .m. t. (6 :16 a .m . c .d .t .) on Sep tem ber 30 , 1994 , a f te r a coun tdow nwi th no unp lanned ho lds . Main eng ine cu to ff (ME CO ) occur red a t273:11:24:35 G.m.t . (00:00:08:35 MET), af ter a nominal launch phase.A l l S S M E a n d R S R M s t ar t s e qu e n c e s o c c u r re d a s e x p e c t e d a n d l a un c h p h a s epe r formance was sa t is f ac tory in a l l r e spec t s . F i r s t st age a scent pe r forman ce w as a sexpec ted . SRB sepa ra t ion , en t ry , dece le ra tion , and w a te r impac t occur red a san t i c ipa ted . Both SRB s were r ecove red and re turned to Kennedy Space C ente r(KSC) fo r r e fu rb ishmen t . Pe r fo rmance o f t he SSM E s, E T , and m ain p ropu ls ions ys tem ( M I S S) was nom ina l.T he w a te r sp ray bo i l e r (WSB) sys t em 2 gaseous n i t r ogen (GN2 ) r egu la to r had twoper iods of in ternal out -of -speci ficat ion leakage whe n the i solat ion valves w ereopened dur ing the p r e l aunch t ime- f r ame . T he i so la t ion va lves were c losed inaccordance w i th nom ina l p rocedures to decrease the sens i ti v it y o f t he G N 2 t anks toin t e rna l r egu la to r l eakage . T h i s i n t e rna l leakage d id no t im pac t t he miss ion .The planned di rect - inser t ion t ra jectory was f lown , and no orb i ta l maneuv er ings u b s y s te m ( O M S ) - 1 m a n e u v e r w a s r e q u ir e d . T h e O M S - 2 m a n e u v e r w a s p e r fo r m e da t 273 :11 :51 :09 G.m. t . (00 :00 :35 :09 M E T ) . T he maneuv er was 99 seconds induration with a"of approximately 160 ft/sec, and the orb i t ach ieved was 119 .7 by119 . 4 nm i .T he pay load-bay -door (PLB ) open ing sequence w as com ple t ed sa ti s fac to r il y a t273:12:49:44 G.m. t . (00:01:33:44 MET) .A t 273:19 :54 G .m. t. (00 :08 :38 M E T ) , Ku-band channe l 2 da t a (opera t ions r ecorderd u m p ) w e r e d e g r a d e d b e c a u s e o f i n t er f e re n c e b e t w e e n c h a n n e l s 2 a n d 3 . K u - b a n dchanne l 3 w as ac t ive a t t he t ime wi th h igh- ra t e da t a f rom Space -borne Imag ingRadar -C (S IR-C) and X -Band Syn the t ic A per tu r e Radar (X-SAR ) . A t273:20 :18 G.m. t . (00 :09 :02 M E T ) , channe l 2 da t a were dumped aga in wi th nom ina lr e su l ts . The impac t was m in ima l s ince channe l 2 ope ra t ions r ecorde r dump s wereavo ided when pay load da t a were be ing down l inked on channe l 3 .

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A 34-minu te was t e wa te r dum p w as in it ia t ed a t 275 :05 :32 G.m. t . (01 :18 :16 M E T ) . Ato ta l o f 108 .8 lb o f wa te r was dum ped in a s ing le dum p cyc le wi th no p rob lems . T hedum p r a t e was a nomina l 2 .01 pe rcen t iminu te .A t approximately 278:04:50 G .m.t . (04:17:34 M ET), the crew repor ted that a t ile wasmiss ing a long the inboard a f t edge o f t he por t- s ide overhead w indow (W 8) . A nanalysis show ed that the loss of th is t i le w ould not imp act on-orb i t or ent ryope ra t ions .A was te wa te r dum p was in i t ia t ed a t 278 :02 :51 G.m. t . (04 :15 :35 M E T ) and w ascom ple t ed 45 minu tes l a t e r wi thou t p rob lems . T wo cy c les were r equ i red , and bo thhad nom ina l dump r a t es o f approx imate ly 2 .0 p e rcen t /minu te . A to t a l o f 106 :5 lb o fw a s t e w a t e r w a s d u m p e d .A t 278:17:59:56 G.m. t . (05:06:43:56 M ET ) , the le f t a ft reac t ion cont ro l sys tem (RC S)t h rus te r L5 D ox id ize r i n j ec to r t emp era tu r e becam e e r r a t i c . A th rus t e r- f a il messag ew a s a n n u n c i a te d a n d t h e t h r u s t er w a s d e s e l e c te d b y t h e r e d u n d a n c y m a n a g e m e n t(RM ) . A genera l pu rpose compute r memory (GM E M ) WRIT E w as app li ed tha tlowered the oxidizer leak de tect ion tempe rature of the vernier thrusters toapprox imate ly 0 F , wi th the fue l l eak de t ec t ion t em pera tu re r em ain ing a t 1 30 F .A t t itude con trol was re turned to the vernier thrusters , and the thruster funct ionednom inal ly for the remainder of the m ission.Pdm afy RC S thruster L3D fai led of f af ter operat ing successfully for num erouspu l ses . T he R C S RM annunc ia t ed a f a i l- o f f cond i tion when th r ee consecu t ive80-m i ll is econd f i r ings had cham ber pre s sure s of l e ss than 10 ps i s . The re w as noi nd ica tion o f a l eak , and the th rus t e r r emained dese l ec t ed fo r t he r em ainder o f t hemission.The con sum able s leve l s r ema ined abov e the mis s ion p lan , and th i s enab led theM ission Ma nagem ent Team (M M T) to fu l f il l the request o f the Payloads Com m uni tyon f l ight day c and ex tend the m iss ion o ne day fo r add i t iona l sc i ence ac t iv i ti e s .A f t e r the f l a sh evapora to r sy s t em (FE S) f eed l ine hea t e r r econf igura t ion to hea t e rsystem 2 a t 278:16:15 G .m.t . (05:04:00 M ET), the FES feedl ine A high- load l inet empera tu r e w en t o f f - sca le h igh (>25 00 F) fo r nea r ly e igh t hour s . T he c r ew swi t chedback to hea t e r sy s tem 1 a t 280 :04 :14 G.m . t (06 :16 :59 M E T ) and a ll tem pera tu r econdi t ions becam e nomina l .A " B C E S T R G 3 M T U " m e s s a ge w a s a n n u n c i a te d a t 2 7 9 :1 3 : 0 5 G . m . t.(06 :01 :49 M E T ) . T h i s m essage ind ica t es a p rob lem in the se r i a l inpu t /ou tpu t (1 /0)da ta pa th be tween the mas te r t iming un i t (MT U ) and the genera l pu rpose compute r(GP C) , inc lud ing m ul tip lexer/demukip iexer (M DM ) f l igh t c r i t ica l fo rward (F F) S. T wogood accum ulators s t i ll existed , and th is fa i lure d id not imp act the f l ight o ther thanthe loss -of MTU redundancy.

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A w a s t e w a t e r d u m p w a s i n i ti a te d a t 2 8 0 : 0 8 :0 8 G . m . t. ( 0 6 0 :5 2 M E T ) a n d w a scom pleted sat isfactor i ly 26 m inutes la ter wi th no problems. Only one du mp c yclewas r equ i r ed , and the dump r a t e was n omina l wi th 81 .8 l b o f .was t e w a te rdum ped . Al so , two supp ly wa te r dum ps were success fu l ly pe r fo rmed . T he f i r s t o fthese dum ps was in i t ia ted at 281:10:01 G.m .t . (07:22.45 M ET) and dur ing the3 0 - m i n u t e d u m p , 7 8 . 7 lb o f s u p p l y w a t e r w a s d u m p e d . T h e s e c o n d d u m p w a sin i ti a ted a t 282:11:00 G .m. t . (08 :23:44 M ET ) and during the 30-m inute dump, 76 .4 lbof supp ly wa te r was dumped .W S B 1 G N 2 r egula tor pre ssure decayed s lowly through out the mis s ion . W hen theW S B 1 G N 2 i so la t ion va lve was o pened fo r en t ry , the sys t em r ep ressu r ized and ther egu la to r p ressu re r eached 25 .2 ps i a f rom the low o f 16 .8 ps i a t ha t had beenr e a c h e d .The f l ight control system (FC S) checkout w as com pleted sat isfactor ily a t283:12:12:38 G.m . t. (10:00:56:38 M ET) , and auxi l ia ry pow er un i t (APU ) 1 ran for4 m inu tes 16 .58 seconds . T he A PU opera t ed nomina l ly w i th 15 lb o f f ue l u seddur ing the checkou t . H ydrau li c sys t em 1 w as used in con junc t ion w i th A PU 1 fo r t hec h e c k o u t , a n d th e s y s t e m p e r f o r m e d n o m i n a ll y . T h e W S B 1 G N 2 isolation valve wasleft closed during the F C S c h e c k o u t b e c a u s e o f th e G N 2 t eak . H ad AP U 1 r equ i redspray coo l ing , t he va lve wou ld have opened to accomm odate sp ray ing ; howev er , theAP U ru n - ti me w as n o t l on g en o u g h t o requ ire an y W SB sp ray co o li n g o f t h e APUlubrica tion o i l. The maxim um A PU 1 lubrica t ion o i l tem pera ture was 20 2 F.A t 283:12:10 G .m.t . (10:00:54 M ET), the rudder channel 3 secondary di f ferentia lp r essu re r equ i r ed approx imate ly 1 .96 seconds to i nc r ease to t he f a i lu r e -de t ec t ionlevel (bypass) dur ing the posi t ive-stimulus por t ion of the seconda ry-actuator checkin the FC S checkou t p rocedure .A s imul t aneous supp ly and was te wa te r dum p w as pe r fo rmed nomina l ly , w i th thesupply dum p beginning at 283:13:50 G.m .t . (10:01:34 M ET). A to tal of 40.1 lb ofsupp ly wa te r was dumped f rom t anks B , C , and D dur ing the 16 -minu te dump. T hewas te w a te r dump w as in it ia t ed 12 m inu tes i n to the supp ly w a te r dump a t283 :14 :02 G.m. t . (10 :02 :46 M E T ) , and a t o t a l o f 126 .9 lb o f was t e wa te r was dum peddur ing the 39 -minu te dum p.A l l s towage and deorb i t p r epara t ions w ere com ple ted in p r epara t ion fo r entry. T h epay load bay d oor s were success fu l l y closed and l a t ched a t 284 :12 :06 :13 G .m. t.(11 :00 :50 :13 M E T ) . T he f i r s t l and ing oppor tun i ty was w aved o f f because o f t hedynam ic wea ther a t KSC tha t was t r end ing toward unaccep tab le l and ing cond i t ions .A d e c i si o n w a s m a d e t o l a n d a t E d w a r d s A i r F o r c e B a s e , a n d t h e d e o rb i t m a n e u v e rwas in i t ia ted a t 284:16:07:19 G.m. t . (11:04:51:19 ME T) , , a n d t h e m a n e u v e r w a s138.5 secon ds in durat ion wi th a A V of 239.1 f t l sec .

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E nt ry w as com ple ted sa t i s fac to r il y , and m ain l and ing gear t ouchdown occur r ed a t t heEd w ard s A i r Fo rce Base co n c re t e ru n way 22 a t 2E-+ :17 :02 :08 G.m. t .( 1 1 : 0 5 :4 6 : 0 8 M E T ) o n O c t o b e r 1 1 , 1 9 9 4 . T h e O r b i te r d r a g c h u t e w a s d e p l o y e dsa t is f ac to r i ly a t 284 :17 :02 .11 G.m. t . , and nose l and ing ge ar t ouchdow n occu r r ed10 second s l a te r . The drag chute w as j e tt i soned a t 284 :17:02 :45 G .m . t, w i th whee l ss top occur r ing a t 284 :17:03 :10 G .m . t. The ro l lou t was n orma l in a l l r e spec ts . Thef li gh t du ra tion was 11 d ays 05 ho ur s 46 m inu tes 08 seconds .T h e W S B 3 G N 2 r egula tor pre s sure was no ted to be dec rea s ing a t a r a te of0.26 psi /minute beginning at 284:17 :18:41 G .m.t . , about 16 m inutes af ter landing.T he pos t l and ing v ideo a l so show ed w ha t appeared to be wa te r d r ipp ing f rom thearea o f t he c en te r li ne l a t ch fo r t he O rb i te r /E T doo r s . T he pos t l and ing inspec t ionde te rmined the source o f th i s wa te r t o be WS B 3 .

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P A Y L O A D S

The Space R adar Laboratory -2 (S RL -2) consisted of a set of dedicated Earthobservation payloads that were u sed to study vegetation, hydrology, tectonics,topography, and global air pollution. The SR L-2 pa yload is comprised of the Space-bome Imaging Radar-C/X-Band Synthet ic A perture Radar (SIR-C/X-SAR), and theMeasurement of Air Pol lution from Satel li te (M AP S). These are the sameinstruments f lown on STS-59 as the SRL-1 payload. Other payloads f lown onSTS-68 include the Biological Research in Canister (BR IO), the Military Applicationsin Ship Tracks (MA ST), the Com mercial Protein Crystal Growth (CP CG ), theChromosome and Plant Cel l Division in Space Experiment (CH ROM EX), and theCosm ic Radiation Effects and Activation Monitor ( C R E A M ) .S P A C E R A D A R L A B O R A T O R Y - 2

The imaging radar included in the SIR -0/X-SAR instruments provided the capabil ityto obtain radar data over virtually any reg ion of the Earth, regardless of weather orsunlight conditions. The SRL -2 flight was planned as a 10-day +2 day mission on a57-degree inclination. However, energy conservation measures added the capabili tyfor another day to the m ission, and this extra day w as added to the m ission at therequest of the Scientific Com mu nity. A s a result , the mission was 11 days induration.The SRL-2 instruments performed exceptionally well throughout the mission. TheSIR-C performed flawlessly from the beginning as did the X-SA R. The Pay load HighRate Recorders (PH RRs) performed acceptably, evan though PH RR-1 w as removedand replaced with an on-o rbit spare after the original recorder fai led to play-backproper ly. I t i s expected that some of the data tapes recorded on PH RR-1immed iately prior to the detection of the problem will not provide useful data.The A pplied Physics Laboratory (A PL) sub-experiment also performed flawlessly andwa s a comp lete success. The radar experime nts overal l had a success rate of about98.5 percent successful data takes against those at tempted. For the sup ersi tesalone, the success rate was almo st 99 percent. The strategy to follow a pre-m issionplanned groun d track was execu ted so well that the last radar data takes occurredwithin one-half minute of the pre-m iss ion predicted m iss ion elapsed t ime and thelook angle of the radar c h a n g e d less than 0.5 degree from the pre-mission plan. Inaddition, the zero doppler steering maneuvers appear to have been very successful.The SIR-C /X-SAR Inst ruments produced over 110 hours of radar data that werewritten on 163 S IR-C and 36 X SA R digital data tapes on the three -- ' ;RRs. D uringthe 950 data-takes, the area of coverag e was in excess of 83 million squarekilometers. The total data-take swat. length w as two million kilometers (all data-take

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:swaths summed as a cont iguous data take) . Tie AP L exper iment produced wav espectra over 1 mill ion l inear kilometers of ocean .The high-rate downlink and subsequent flow to the Mission Control Center (MC C)and Jet Propulsion Labo ratory (JPL) worked v ery well . The JPL ground productssystem processed approximately 40 scenes using the high-precision processor,three scenes using data f rom al l three f requencies and numerous spec ia l products.X-SA R processed num erous X-band passes on the real- t ime processor andproduced special image products for display and evaluation.One of the bonuses of flying SIR-M -SA R for the second time was the opportunityto demon strate a different data-gathering method called interferometry from theShuttle platform. Scientists conducted the highly successful interferornetryexperimen ts during the last three day s of the flight. The Scientists were ab le togenerate digital elevatior. models (topograph y) of the Earth's surface. Fringes w erefound in scenes taken from the SRL -1 fl ight in A pril and the SRL-2 fl ight , as well asscenes taken on success ive days dur ing the SRL -2 miss ion. C hanges in topographywere foun d in Long Valley Caldera, Ca lifomia, and in Kilauea, H awaii . Topographicmaps w ere also produced of M amm oth Mountain, Cal i fornia. A digital elevat ion m ap(DEM ) and a perspect ive image w ere produced for M t . Etna in Sici ly from the repeat -pass da ta .The M A PS instrument performed flawlessly, as i t did on the STS-59 m ission. Theexperimenters w ere again extremely pleased v jdh the stabili ty of the therm al controlloop, given the sun ang les at the time of year that this mission was flow n. TheM AP S experiment was 10 0-percent successful and the data quality w as excellent.A t the conclusion of the mission, 256 hours of MA PS data had been accum ulated,and i t covered a l l of the planned corre la t ive m easurement s i tes . These data wereenhanced by an excel lent se t of crew observat ions .

C H R O M O S O M E A N D P L A N T C E L L D I V I SI O N I N S PA C E E X P E R I M E N TSTS-68 w as the fifth fl ight of the CH RO ME X experiments that examined the effectsof micrograv ity on a wide range of phy siological processes in plants. Theexperiment opera tions are flown in an au tomated plant grow th unit , which is locatedon the Shuttle middeck . The crew perform ed daily status checks of the unit and itperformed nom inally throughout the flight.

C O M M E R C I AL P R O T E I N CR Y S T A L G R O W T H E X P E R I M E N T .The C PC G experiment grew and retrieved crystals in microgravity as well asprovided data on the dynam ics of prote in crysta ll izat ion. The C PC G was act ivated a t273:18:05 G .m.t. (00:06:49 M ET), and the timeline sequence wa s initiated40 m inutes later. Early in the m ission, the com mercial refdgeratorrincubator m odule(GR IM) temperature was e levated because of h igher-than-expected cabin

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temperatures. After the cabin temperatures returned to expected levels, the GR IMtemperature stabilized and remained at that level throughout the rem ainder of themission. The end of the mission timeline sequence w as deleted at 284:04:27 G .m.t.(10:17:11 ME T), and CP ( 'G preparations for ent ry were com pleted seven minuteslater.

B I O L O G I C A L R E S E A R C H I N C A N I S T E R S E X P E R IM E N TSTS-68 was the first flight of the ERIC experiment which provided data in the area ofl ife sciences. The BR IC hard ware is self-conim]ned and requires neither Orbiterpow er nor any crew interface. Postfl ight evaluation is required to determine thesuccess of the BRIG experiment .

C O S M I C R A D I A T I O N E F F E C T S A N D A C T I V A T I O N M O N I T O R E X P E R I M E N TThe C REA M experiment col lected data on cosm ic ray energy loss spectra, neut ronfluxes, and induced radioactivity using active and passive mo nitors. The C RE A Mmon itor was activated at 273:18:41 G .m.t . (00:07:25 M ET), and the passive monitorswere placed around the cabin about tw o minutes later. The crew m oved the activemon itor to the stat ion 1 posit ion at 275:13:01 G .m.t . (02:01 :45 M ET). i t was thenmov ed to the stat ion 2 posit ion at 277:18:42 G.m.t. (04:07:26 M ET), to station 1 at279:16:27 G .m.t . (06:05:11 M ET), and to stat ion 1 again at 281:20:18 G .m.t .(08:09:02 ME T). The CRE AM act ive m oni tor was stowed at 282:16:21 G .m. t.(09:05:05 M ET), and the passive monitors were stowed prior to entry.

M I L IT A R Y A P P L I C A T I O N S O F SH I P T R A C K S E X P E R I M E N TThe M A ST experim ent collected data on ship pollutants and their effects on thereflective properties of clouds. No M A ST oppo rtunit ies were sched uled in theprefl ight t imeline, as MA ST tur gets are depen dent upon w eather condit ions.Upcom ing MA ST oppo rtunities were submitted to the Flight Control team on eachplanning shift as agreed upon prior to fl ight. The crew reported comp leting nineMA ST oppo rtunit ies that included the Kamc hatka peninsula, the Sea of Okhotsk, andthe Ca lifornia coast .

G E T A W A Y S P E C I A L SThe GA S payloads consisted of seven experiments flown in three GA S canisters.The experiments were:

a. G-316 - One experiment provided data on the Effects of Microgravi ty onSurvival, Mat ing, and Development of Milkweed B ug, and the second experimentprovided data on the Microgravity Effects on Growth Q uali ty and Size of C rystal ofRochel le Sal t. The G AS canis ter G-316 was v er i fied to be act ivated a t278:20:19 G .m.t. (05:09:03 M ET). The G -316 canis ter was a lso powered dow n on

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f l igh t day 1 2 , a s p l anned , f o r en t ry . T he sponsor o f t h is G A S can i s t e r i s the con tac tfor the resul ts of th is exper iment .

b . G-503 - T he G-50 3 can i s t e r con ta ined four exper imen t s , wh ich were :1. M icrogravi ty and C osmic Radia t ion Effec ts on Dia toms;2. Con crete Cur ing in M icrogravi ty ;3. Root G rowth in Space ; and4. Microgravi ty Corros ion.T he G -503 G A S can i s t e r was ve r if ied to be ac t iva t ed a t 273 :20 :11 G.m. t .(00 :08 :55 M E T ) . E n t ry p r epara t ion ac t iv i ti e s were com ple ted as p l anned on f li gh tday 1 2 . T he spo nsor o f t h i s GA S can i s te r i s t he con tac t f o r the r esu l t s o f t h isexper iment .

c . G-541 - The Study o f Breakdow n of P lanar Sol idPl - iqu id In terface duringCrys t a l Growth - T h i s 9 . .pe r imen t was com mand ed on a t 273 :20 :19 :35 G.m. t ., andcomm anded o f f a t 274 :17 :57 :32 G.m . t. (01 :06 :41 :32 M E T ) . T he sponsor i s thecontact for resul ts of th is exper iment .

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V E H I C L E P E R F O R M A N C E

A n a t t empt was m ade to l aunch th is veh ic le on A ugus t 18 , 1994 , however , t hel aunch w as abor t ed a t 230 :10 :53 :59 .157 G .m. t . n s a r esu l t , t he Space V eh ic l e wast aken f rom the l aunch pad tt o t he VAB where the th r ee main eng ines werec h a n g e d . T h e s u c c e s s f u l la u n c h o f t h e S T S - 6 8 m i s s io n o c c u r r ed a t273:11 :16 :00 .011 G .m. t . on Sep tem ber 30 , 1994 . T h i s sec t ion o f t he r epor td i scusses t he l aunch ab or t a s w e l l a s t he f l igh t .SOLID ROCKET BOOSTERLaunch Abort

T he SR B pre launch coun tdown w as normal fo r t he launch a t t empt on Augus t 18 ,1994 . T here were no SRB Launch C omm i t Cr i t e ri a (LCC ) v io l a tions . OneOpera t ions and Main tenance Requ ir emen t s and Spec i f ica t ion Docum ent (OM RSD )violat ion occurred wh en the left -hand System A Ran ge Safety bat tery temperatured ropped o f f - sca le l ow. A l l o the r SRB sys t ems per fo rmed as expec ted dur ing thel aunch a t t empt .L a u n c h

A ll SRB system s per formed nom inal ly dur ing the launch of the STS-68 vehicle . Thecoun tdown was normal and no SRB LC C or O MR SD v io l a tions occur r ed . For t h isf l ight , the low -pressure heated grou nd purge of the SR B af t ski r t was used tomain ta in the case /nozz le j o in t t empera tu res w i th in the r equ i red L CC r anges . AtT-25 m inutes , the purge w as act ivated at h igh pressure to inar t the SRB af t ski rt .One SR B-re la ted in -f ligh t anomaly occurred in conjunct ion w i th th i s f l igh t . Thel e ft - hand SRB range sa f e ty sys t em (R SS) th rowaw ay cab le assemb ly , wh ich i s u seddur ing g round t es t o f the R SS , w as found to have cu t s i n t he cab le jacke t (F l igh tProb lem S TS-68 -K-1) . Thi s anom a ly has been a s s igned to the Kennedy S paceCe nter for resolution.Bo th SRB s were success fu l ly separa t ed f rom the E T a t T + 123 .96 seconds , andvisual s ight ing repor ts f rom the recovery a rea indicate that the decelerat ions u b s y s te m s p e r f o r m e d a s d e s ig n e d . B o t h S R B s w e r e o b s e r v e d d u r i n g d e s c e n t a n daf ter landing, both w ere observed f loat ing approximately 15 m i les f rom the re t r ievalships.

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R E D E S I G N E D S O L ID R O C K E T M O T O RL a u n c h A b o r t

No R SRM L C C o r OM RSD v i o la t io n s were i d en ti fi ed d u ri n g th e l au n ch abo rtcountdo wn . Powe r up and operat ion of a l l igni ter and f ie ld- jo int heaters wasaccom pl ished nom ina lly . Al l R S R M t empera tu r es w ere ma in ta ined w i th in accep tab lel imi ts throughout the countdow n.L a u n c h

No R SRM LC C or O M RSD v io la t ions occur red dur ing the launch coun tdown. Powerup and op erat ion of the igni ter and f ie ld- jo int heaters wa s accom pl ished nom inal ly .A l l RS RM temperatures we re maintained wi thin acceptab le limi ts throughout thecoun tdown.Field jo int heaters operated for 11 h ours 25 m inutes (23 hours to ta l including thel aunch abor t ) . Pow er was appl ied to the hea t ing e lement an ave rage of 15 pe rcentof the t ime d ur ing the LCC t ime-f rame to m aintain required temperature levels .Ign i te r jo in t I . _ -Aers opera ted for 18 hours 19 m inutes (36 hours 9 m inutes to ta li nc lud ing l aunch a bor t ). Pow er wa s app l i ed to t he ign it e r hea t ing e l em en t s anaverage o f 29 pe rcen t o f t he LC C t ime f r ame to m ain ta in p roper tempe ra tu res .The a f t ski rt thermal condi t ioning was o perated per iodical ly to maintain the f lexb e a r in g t e m p e r a tu r e a b o v e 6 0 O F an d the nozz le - to - case jo in t tem pera tu r e above75 F . To ensure a l l haza rdous tcombu s t ib le ga se s we re r emoved f rom the a f tcom par tment , the af t skir t purge was operated at h igh f low -rate from T -15 m inutesth rough l aunch .Data indicate that the f l ight per formanc e of both RSR M s was w el l wi thin the contractend i t em (CE I ) spec i fi ca tion l imi t s , and w as t yp ica l o f t he pe r fo rmance obse rved onprev ious f ligh t s . The R SRM prope l l an t mean bulk t emp era ture was 80 F . The t ab leon the fo l lowing pa ge p r esen t s t he more de t a i led p ropu l s ion pe r fo rmance da t a fo rth e R S R M s .A ll avai lab le data were reco rded, t ransmit ted and analyz ed, and no in- f l ightanom al ies were ident i f ied f rom the da ta rev iew. The post f l ight inspect ion of them otors a lso indicated nom inal per formance , wi th a ll jo ints per form ing as designed.

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R S R M P R O P U L S IO N P E R F O R M A N C EParame te r Left molar , 80 O F Right motor, 8 0 O FPredictedActua l Predicted Actua lImpu l se ga t es1-20, 10 6 Ibf -sec 66.12 65.92 6 6 . 0 6 65 .901-60, 10 6 tbf-sec 176.05 175 .70 175 .90 175 .77I - A T 1 0 6 Ibf-sec 296.93 297 .16 296.90 296.60Vacuum Isp, ibf-sec/ibm 268.6 267 .9 268 .6 2 6 8 . 3Bum ra te , in /s ec @ GO O F 0.3678 0 .3685 0 .3676 0 .3682a t 625 ps iaB u m r a te , in / se e @ 8 0 O F 0.3731 0 .3738 0.1 ?9 0 . 3 7 3 5a t 625 ps iaE ven t times , secondsIgnition interval 0.232 N/A 0 .232 W AWeb time 108 .9 108 .8 1 0 9 . 1 0 108 .6Sepa ra t ion cue , 50 ps ia 118 .6 118 .4 1 1 8 .7 1 1 8 .5Action t ime 2 120 .7 120 .6 120.8 120 .5S e p a r a ti o n c o m m a n d 123.6 123 .4 123 .6 123 .4P M B T , O F 80 80 80 80

M aximum igni t ion r ise ra te , 90.4 N/A 90 .4 N/Asia'10 msD e c a y t im e , s e c o n d s 2 .8 T-2-9 2 .8 2.859 .4 Ps i a t o 85Tai loff Imb alance Impulse Predicted Actualdifferentia! Kibf-sec N /A 202 .0Impu lse Imbalance = lef t mo tor minus r ight mo tor' Al l t imes a r e r e f e renced to ign i ti on comm and t ime excep t w here no ted by a 2 .2 Referenced to lif toff t ime ( ignition interval).

E X T E R N A L T A N KL a u n c h A b o r t

A l l ob jec t ives and r equ ir emen t s assoc ia t ed wi th E T p rope l lan t l oad ing were m et . Al lE T e l ec t ri ca l equ ipm en t and ins t rum en ta t ion op era t ed sa t i sf ac to r il y . E T p urge andhea te r opera tions were moni to r ed and a l l pe r fo rmed p roper ly . No E T LC C o rOM RSD v i o la t io n s o ccu r red .T ypica l i ce /f ros t fo rmat ions were obse rved on the E T dur ing the coun tdown. T herewas no i ce or f ros t obse rved on the ac reage a rea s of the ET. N orma l quant i t ie s of

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ice and/or f rost were prese nt on the l iquid oxyge n (1-0 2 ) and liquid hydrogen (1-1-112)f eed l ine s and on the pre s sur iza t ion l ine b racke t s . A l l obse rva t ions w e re acceptab lep e r N S T S 0 8 3 0 3 . T h e I c e /F r o s t R e d T e a m w a s n o t u s e d b e c a u s e o f a r e c e n tc h a n g e t o t h e L C C . T h e D e b r i s te a m r e p o r t e d n o t h in g u n u s u a l o n t h e E T . T h e E Tpressur izat ion system funct ioned nominal ly throughout engine s tar t .

LaunchThe E T loading and f l ight per formance w as excel lent . A l l f l ight ob ject ives wereaccompl ished. Al l ET elect r ical equipment and inst rumentat ion operated proper ly .A l l E T p urge and hea te r opera t ions w ere mon i to r ed and a l l pe rfo rmed p rope r ly . NoET L CC o r OM RSD v i o la t io n s o ccu rred .The no se cone purge hea te r and t empera ture cont ro l sys tem op e ra ted sa ti s fac tor i ly .M easured nose cone f low- ra te w as w i th in the I n te r face C on t ro l Docum ent ( ICD)requ i rem en t s , a s i t has been s ince KSC ins ta l led a c r i ti ca l f low nozz le t o l imi t 'hef low ra te .T ypica l l ce /f ros t fo rmat ions w ere obse rved on the E T dur ing the coun tdow n. T herewas no i ce or f ros t obse rved on the ac reage a rea s of the ET. N orma l quant i f ie s ofi ce and/or f ros t we re pre sen t on the L 0 2 a n d L H 2 feedlines and on thepressu r i za tion l ine b r acke t s , and som e f ros t o r ice w as p r esen t a long the LH 2pro tuberance a i r l oad (PA L) r amps . Al l obse rva t ions were accep tab le pe r NS T S0830 3 , , T he I ce /Fros t Red T eam repor t ed tha t no anom alous the rmal p ro tec t ionsys t em (T PS ) cond i t ions ex i s t ed , a lt hough on e accep tab le c r ack d id ex i st a t t hefoam b r idge be tween the ve r t ica l s t ru t cab le t r ay and i t s f it t ing and tha t was cau sedby joint rotation.Prope l l an t tank load ing wa s nom ina l . A l l L0 2 an d L H 2 t ank u l l age pre s sure s we rewi th in accep tab le l imi t s t h roughou t l oad ing , p r ep ressu r iza t ion , and f li gh t . Geyserp reven t ion p rocedures p rov ided exce l l en t t empera tu r e ma rg ins th roughou t l oad ing .T he E T p ressu r i za t ion sys t em func t ioned no mina l ly t h roughou t eng ine s t a r t andf l igh t . T he min imum L0 2 ul lage pre s sure expe r ienced du r ing the u l l age -pre s sures lump w as 14 .2 ps id .E T s e p a ra t io n o c c u r r e d w h e n c o m m a n d e d . E T e n t ry a n d b r e a k u p o c c u r re d 1 7 n m i .uprange of the pref l ight predict ion an d w i thin the e xpected footpr in t .Post f l ight analysis of the f i lm f rom the um bi l ical wel l cam eras, as wel l as f rom theonboard cam era opera t ed by the c rew in suppor t o f Deve lopmen t T es t O b jec t ive(DT O) 312 , revealed the fo l lowing:

1 . T w o d ivo t s , approx imate ly 10 to 12 inches in d i amete r , in o r j u s t f o rward o fthe LH 2 - toin tPr tank spl ice on the -Z side of the E T;

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2. A shal low d ivo t , approxim ate ly 5 inches in d iameter , in the LH 2 insulat ionaf t of the in ter tank spl ice and ou tboard of the -Y b ipod at tachme nt .3. M issing foam , approximately 10 inches in length , wi th probable exposedprimer from an in ter tank s t r inger top near the +Z axis a t approximate ly s ta t ionXT-1050 .S P A C E S H U T T L E M A I N E N G I N E S

Launch AbortA l l SSM E param ete r s appeared to be normal t h roughou t the p r e l aunch coun tdown ,and the pa ram ete r s were t yp ica l o f t he p r e launch param ete r s obse rved on p rev iousf ligh t s . E ng ine r eady w as ach ieved a t t he p roper time and a l l LC C w ere met . An o n-pad abor t occur red a t 230 :10 :53 :58 .157 G .m. t. b ecause the SSME 3 (S1N 2032) h ighpressu re ox id i ze r t u rb ine (H PO T ) d i scharge t empera tu r e channe l A exceeded a p r e -l i ftoff redl ine check result ing in a fai lure identificat ion (FID) and subsequent engineshu tdown (F l igh t Prob lem ST S-68-E -01) From eng ine s ta r t comman d (E SC ) p lus2 . 3 s e c o n d s t h ro u g h E S C p l u s 5 .8 s e c o n d s , t h e H P O T d i sc h a r g e t e m p e r a tu r e m u s tn o t e x c e ed 1 5 6 0 R . T h e S S M E - 3 H P O T d i s c h a rg e t e m p e r a tu r e C h a n n e l A a t ta i n ed1 5 7 6 R . T h e C h a n n e l B m e a s u r e m e n t a t ta i n ed 1 5 3 0 , 1 11, and tha t w as a l so h igherthan pred ic ted . Da ta r ev iew ind ica te s tha t the da ta a re v a l id .S S M E 3 w a s c o m m a n d e d t o s h u t d o w n a t E S C p l u s 4 . 7 2 se c o n d s . S S M E 2 a n dS S M E 1 s u b s e q u e n tl y s h u t d o w n a t E S C p l u s 5 .8 0 s e c o n d s a n d 6 . 9 6 s e c o n d s ,r e spec t ive ly . The shut dow ns were a l l nom ina l and p laced the vehic le in a s a feconfigurat ion.T he SS M E 1 inspec tion fo llowing the abor t r evea led a c r ack in the tu rb ine d i schargeshee t meta l tu rnaround duc t o f the SSM E 1 h igh p ressu re fue l t u rbopump (H PF T P)(F l igh t Prob lem ST S-68-E -02) . T he c r ack was 4 .5 inches long , wi th two c r acks(0 .8 inch and 0 .9 inch long) runn ing 90 degrees to t he long c r ack , m ak ing a f l ap .T he f l ap w as de f l ec t ed ou tboard touch ing the coo lan t l i ne r. Degrada t ion o f t heturb ine per formance w ould be sm al l from this condi t ion , and the engine i s to lerant topar t ic le gene rat ion of th is s ize in th is area.

LaunchAl l SSM E paramete r s were normal t h roughou t the coun tdown and were t yp ica l o fpre launch pa rame te r s obse rved on p rev ious f ligh t s . En gine r eady was ach ieved a tt he p roper time , a l l LC C w ere met , and an on- t im e star t and thrust bui ldup werenormal .Fl ight data indicate that SSME performanc e dur ing mainstage, throt tl ing , shutdown ,and p rope l l an t dumping op era t ions w as norm al . T he spec i f ic impu l se ( I sp ) was

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ra ted a t 452.0 seconds. H igh pressure oxidizer turbopump (H PO TP) and H PO TPtemperatures were w ell within specification throughout engine operation. ME COoccurred at T+ 513 .4 seconds. There were no FID s or significant problems identifiedfrom the data.A re view of the launch data has reve aled the following i tems of interest:

1. The SSM E 1 H POTP discharge temperature channel A shifted down atengine start plus 240 seconds. The shift is attributed to a reduction in H PO TPcavitation. This same condition was ob served on ST S-59 (previous flight of thispum p) and is within the experience base.2. The SSM E 1 a nti-flood valve skin temperature 2 failed high at engine start

plus 95 seconds , and the no . 1 m easurement was s low to respond. The mostprobable cause is that the sensors are debonde d. The sensors w ill be replacedprior to the next flight of this engine.3. The SSM E 1 m ain combustion chamber (M CC ) pressure channel Alspiked to 84 psia at engine star t plus 292 seconds. This w as a s ingle event spikeand caused the cha nnel to be tempo rarily disqualified for one ma jor cycle. Eventhough the sensor operated properly for the remainder of the flight, it was rem ovedand troubleshooting wa s perform ed. Microfocus X -ray identified a part icle inside thesensor that could account for the spike. The sensor has be en sent to the vendor foradditional analysis.4. The SSM E 2 M CC hot gas in ject ion pressure froze and recovered a tengine start plus 270 seconds. This condition was w ithin past experience.5. The SSM E 2 H PO TP system pressure dipped a t engine cutoff p lus2.5 seconds. This cond i t ion is w i thin the e xper ience base .

S H U T T L E R A N G E S A F E T Y SY S T E ML a u n c h A b o r t

The Shut t le Range Safety Sy stem (SRS S) c losed- loop tes t ing w as completed asscheduled dur ing the launch countdown. Al l SRSS safe and arm (S& A) deviceswe re ar: led and system inhibits turned off at the appropriate t imes. A ll SRS Smeasurem ents indicated that the system operated throughout th e launch abortcountdow n as expected with the exception of the left-hand System A b atterytemperatu re . The System A battery temperature dropped off-scale low (18 I F) . Anexception was written to the OM RSD requirement of 34.6 to 103.4 F. All SRSSdevices performed as planned for the on-pad launch abort .

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A nalys is o f t he ba t t e ry t em pera tu re p rob lem ind ica t es t ha t t he m easuremen t f a i l edas a step- funct ion , lnd ic^~ 'ng an ins t rum enta t ion fa i lu re . Vol tage and cu rren tr emained s t ab le du r ing the m easurem en t f a i lu r e . T he f a i lu r e s igna tu re ind ica t es anintermittent open c i r cu i t fo r t he t empera tu r e measurem en t (thermistor) . The bat terywas r em oved and t es t s were pe r fo rmed to i so l a t e the cause o f t he anom aly .

Launch

T he SR SS c losed- loop t es ting was com ple t ed as schedu led dur ing the l aunchcoun tdown. Al l SRSS S& A dev ices were a rmed and sys t em inh ib it s t u rned o f f a t t heprope r t ime . A l l SRSS measurem ents ind ica ted tha t the sys tem op e ra ted a sexpected throughout the countdow n and f l ight .A s p ianned , t he SRB S& A dev ices were sa t ed , and SRB sys t em power wa s tu rnedoff pr ior to SRB separat ion. The ET system remained ac t ive unt il ET separat ion f romt h e O r b i t e r .

O R B I T E R S U B S Y S T E M SMain Propulsion System

(Launch A bor t : T he overa l l pe r fo rmance o f t he MP S w as as expec ted th roughou t thecountdow n and dur ing engine s ta r t and shutdow n. T h e L O 2 a n d L H 2 l oad ing wa sperformed no minal ly wi th no s top - f lows or reverts . No O M RSD or LOG vio la t ionso c c u r r e d .Throu ghou t the per iod of pref l ight operat ions, no s igni f icant haza rdous gasconcen t r a t ions were de t ec t ed . T he m ax imum hydrogen co ncen t r a t ion l eve l in t heO rbi ter af t com par tment oc curred shor t ly af ter s tar t of fast - fi l l and was approximately153 pp m, and tha t compares f avorab ly wi th p revious da ta for th i s veh ic le .A com par i son o f t he ca l cu la ted p rope l l an t loads a t t he end o f r ep len i sh ve r sus theinventory loads resul ts in a loading accuracy of -0 .026 percent for LH 2 and+ 0 . 0 3 5 p e r c e n t fo r L O 2 .L a u n c h : T h e o v e ra l l p e r fo r m a n c e o f th e M P S w a s n o m i n a l. N o L C C o r O M R S Dv i o la t io n s o c c u r re d .LH 2 l oad ing opera t ions were norm al t h roughou t t he p r e l aunch t ime- f rame and w ereperformed as p lanne d wi th . no s top - f lows or revert s . Analys i s o f the LH 2 loadingsys tem da ta showed the load to be 231 , 886 lbm a t t he end o f r ep len i sh . Acom par i son wi th the p l anned load show ed tha t an excess o f 33 I bm w as loaded ,providing a loading accuracy of +0 .01 percent , which i s w el l wi thin the requiredaccuracy.

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L02 l oad ing opera t ions were norm al t h roughou t t he p r e l aunch t ime- f rame and w ereper fo rmed w i thou t any s top - flows o r r ever t s . Ana lys i s o f t he L 0 2 loading systemda ta showed the load to be 1 , 388 ,337 Ibm a t the end of r ep len i sh . A com par i sonwi th the p l anned load showed tha t an excess o f 508 Ibm was loaded , p rov id ing aloading accuracy o f +0.04 percent , wh ich i s wel l wi thin the required accuracy .Throu ghou t the per iod of pref l ight operat ions, no s igni f icant hazard ous gasconcen t r a t ions were de t ec t ed . T he m ax imum hydrogen co ncen t r a t ion l eve l in t heOrb i t e r a ft compar tmen t w as approx imate ly 150 ppm , and tha t compares f avorab lywi th prev ious d ata for th is vehicle .A scen t MP S per fo rmance w as comple t e ly nomina l and no anomal i es were iden ti f ied .Da ta ind ica t e t ha t t he L0 2 a n d L H 2 pre s sur iza t ion sys tems pe r formed a s p lanned ,and tha t a l l ne t pos i t ive suc t ion p r essu re (NP SP) r equ i r emen t s we re met t h roughou tthe f l igh t . T he gaseous hydrogen f low con t ro l va lves pe r fo rmed nom ina lly .T h e M P S g a s e o u s o x y g e n ( G O 2 ) pressur izat ion system fai led the OM RS D F i le IXrequ i rem en t fo r on -o rb it decay . A de te rmina t ion o f t he amoun t o f l eakage f rom theoxygen p ressu r i za t ion sys t em i s m ade by m ea . :u ring the p r essu re decay o f t he G0 2m anifold following m anifold pressur izat ion. The calculated on-orb i t leakag e was34 .8 sc im , and the a l low ab le l eakage i s 24 .5 sc im. F a i lu r e o f t h i s r equ ir emen t wi l lnecessitate the perforriance of the G02 pre s sur iza t ion l eakage check pe r theOM RSD Fi l e I II t o i so l a te t he cause o f t he l eakage .T he p rope l l an t dump and v acuum iner ting opera t ions we re pe r fo rmed under t he0I -22 so f tware in a nom ina l manner . T he p rope l l an t dump w as in i ti a t ed a tM E C O p lus 122 seconds as p l anned , and the pos t f l igh t ana lys i s i nd ica ted nom ina lope ra t ions . The vacuum ine r ting w as a l so nom ina l . Thi s was the l a s t fl igh t o f the01-22 so f tware .In preparat ion for ent ry , the ma nifold repressur izat ion was nom inal . A total of57.5 lb of hel ium (nom inal), was used d ur ing ent ry on th is vehicle .

R e a c t io n C o n t r o l S u b s y s te mT he R CS per fo rmance was nomina l ; however , two anomal i es were iden t if ied f romthe da ta . The RC S w as in te rconnec ted to the l e ft and r igh t OM S, and dur ing thei n t e rconnec t opera t ions the RCS used a t o t a l o f 2533 Ibm of O M S propellan ts . I naddit ion, 4658.8 Ibm of R CS propel lants were consumed by the RC S.Du ring th is f l ight , a successful a t tempt wa s mad e to obtain high-rate data on al l RC Sthrus te r s so tha t t he R CS ho t - f ir e p r io r t o en t ry cou ld be e l imina ted . A l l th rus t e r se x c e p t F 3 F w e r e v e r ged w i th h igh- ra te chambe r pre s sure da ta . S ince th i s th rus te rwa s not a h igh-pr ior i ty thruster for ent ry , the RC S hot- f i re was e l iminated.

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At 278:17:59:56 G.m.t. (05:06:43:56 M ET), the left aft RC S thruster 'l-51) oxidizerinjector temp erature becam e erratic (Flight Problem S T S -68-V-02). A fuel leakmessage w as annunciated and the thruster was deselected by the RM . Fl ight rulesprohibit vernier operation with a v ernier thruster deselected; consequently, theprimary thrusters were used for v ehicle a*fi tu de control . Data analysis showed thatthe data signature was ty pical of an intermittent open instrumentation sensor orwiring, most l ikely between the sensor and ded icated signal conditioner. Atemporary w orkaround was implem ented that al lowed vernier operations only whenreal-timedownlink of the L.SD fuel injector temperature and chamberpressure (Pc) w ere available, and with data losses of no greater than 30 seco nds.Subsequently, a more permanent workaround was implemented after verification inthe Shuttle A vionics Integration Laboratory (SAIL) in which a GM EM WR ITE wasapplied. The GM EM lowered the oxidizer leak detection temperature of the vernierthrusters to approximately 0 F, with the fuel leak detection temperature rem aining at130 F. Leak d etection for al l vernier thrusters was provided by the fuel injectortemperature. Atti tude control was returned to the v ernier thrusters, and the thrusterfunctioned nom inaly for the rema inder of the mission.At approximately 279:05:00 G .m.t. (05:17:44 M ET), the left aft primary RC S thruster1-31) was de clared failed off and deselected by the RM after having beensuccessfully fired 399 time s. The failure occurred after three consecutive 80 m spulses during wh ich the chamber pressure never reached m ore than 10 psia (FlightProblem STS-68-V-03 ). There was no indication of a leak, and the thrusterremained deselected for the rem ainder of the m ission. Data review indicates thatthe thruster did not fire nominally. Injector thermal trends indicate propellant flowthrough both v alves, but the data did not show the typical soak-back that Is Ind icativeof a nom inal firing. Inertial measuremen t unit (IMU) veh icle rate data confirm lowthrust output for the UD firings.

O r b it a l M a n e u v e ri n g S u b s y s t e mThe O MS perform ed nominally during the mission, comp leting two maneu vers -O M S - 2 and the deorb it firing. The total firing time on the eng ines was236.3 seconds, with 12,31 4 Ibm o f propellants being used. In addition, the RC Sused 2533 Ibm of the OM S propel lants . Detai ls of the two O MS fir ings are shown inthe following table.

OMS F IR INGS Firing A V ,OM S firing Engine Time, G.m.tJMET duration, fUsecsecondsOMS-2 Both 273:11:51:09:9 G.m.t . 98.0 160.100:00 , 36:09.9 ME TDeorbit Both 284:16:07:19.3 G.m.t . 138.3 239.211:04:51:19.3 M ET

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Tw o minor problem s were noted, neither of which affected the m ission. The firstwas the left fuel total quantity m eter reading high. The aft probe w as readingcorrectly; however , the forward probe w as not . The problem has been docum entedat KSC ; however, corre ctive action will probably no t be taken unti l this vehicle goesto Orbiter maintenance down period (OM DP).Also, the right oxidizer total quantity reading w as high. The aft probe was readingapproximately the sa me value as total quanti ty . Prel iminary .alysis indicates thatthe aft probe and its electronics are suspect. This problem w as initially noted onSTS -59, and KSC docum ented i t at that t ime for future corrective action.

P o w e r R e a e t a n t S t or a g eand D i s tr i but ior : -3 ubsys temThe operations of the power reactant storage and distribution (PRSD) subsystemwas nom inal. A total of 3,061 Ibm of oxygen was used, including 128 Ibm that wasconsume d by the environmental control subsystem s. A lso, 369 lbm of hydrogenwere used. Reactants remaining provided a mission extension capabili ty of 54 hoursat a miss ion average pow er level of 15.8 W. There w ere no anom alies ident if iedfrom the data for this subsystem.At 280 :03:16 G.m.t. (06:16:00 ME T), usage was switched to hydrogen tanks 1 and 2for the next 36 hours. During m ost of the cycles for the first 12 hours following theswitch to tanks 1 and 2 , hy drogen tank 2 p ressure rose faster than the tank 1pressure and m anifold pressures when the heaters were on. T his condi t ionindicated that the hydrogen tank 2 check valve was s t icking c losed. H owever , thetank 2 pressure dec lined norm ally during the heater-off cycle, and this indicates thatthe check valve wa s opening enough to allow some flow and prop erly deplete thetank but not enough to increase m anifold pressure. Similar behav ior was noted forthis sam e hydroge n tank 2 check valve during the previous fl ight of the OV-105vehicle (STS-59). At 280:18:56 G.m.t . (07:n7:40 MET), the manifold pressureabruptly rose approxim ately 8 psi from the tank 1 pressure to the tank 2 pressure.This indicated that the hydrogen tank 2 check valve suddenly opened or b ecameunstuck. After th is occurrence, hydrogen tanks 1 a nd 2 and the manifold pressuresal l tracked each o ther proper ly for the res t of the miss ion. There was no miss ionimpact from this condition.

F u e l C e l l P o w e r p l a n t S u b s y s t e mThe fuel cel l powerplant (FCP ) subsystem performed nominal ly throughout themission with no prob lems or anom alies identified in the data. The fuel cellsgenerated 4 ,260 kW h of 'e lectr ic i ty a t an average pow er level of 15.8 kW and theload was 516 am peres. The fue l co ls consumed 2933 ibm of oxygen and 369 Ibm ofhydrogen, and generated 3302 Ibm 0 w ater dur ing the miss ion.

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Main buses B and C were t ied for most of the mission to support the payload. Fivefuel cell purges we re perform ed, occurring at approximately 24, 91, 163, 212 , and261 hou rs mission elapsed time. Fo r this mission, the mean p urge interval was only59 hours . No purge in terval of 96 hours w as achieved because of the higheraverage load that led to a more rapid performance deca y.A uxi li ary Power U ni t Sub sys tem

The A PU sub system performe d satisfactori ly throughout the mission with noproblems or anom al ies ident if ied from the data. The A PUs were shut dow n afterascent in the 2, 1, and 3 order to fulfi ll the requiremen ts of DTO 414 , Sequence B .The results of the DTO are discussed in the Developm ent Test Objectives S E.ion ofthis report .During the scrubbed launch attempt, the AP U 2 exhaust gas temperature (EGT )1rose sharply at start-up, then followed a norm al profile but w as biased high. Thissame b ehavior was a lso noted dur ing the ascent and entry phases of the miss ion,but to a lesser extent.A ll three A PU s had the ne w w ater valves instal led for their first fl ight. These valvesare not l ife-limited because of corrosion. The prev ious design was sub ject tocorrosion, which caused the bellows to stick open or closed; hence the valves werelimited to a nine-month w etted life.The A PU 1 gearbox lubrication (lube) oil outlet temperature fau lt detection andannunciation (FDA ) limit was lowered to provide an FDA message ea rly and allowsufficient time for the crew to open the WS B G N 2 isolation valve that is opened fornormal lubrication oil cooling operations (250 F) during FCS checkout. However,opening the valve w as not required.The A PU fuel consum ption and run-time by A PU posit ion and serial number isshown in the following table.

Flight phase APU 1(SIN 403) APU 2(S/N 311 ) A P U 3(S/N 410)Time,min:sec Fue lconsumpt ion,lb

Time,min:sec Fuelconsumption,lb

Time,min:sec Fuelconsumpt ion,I bAscent 19:00 48 18:44 48 19:12 48FCS checkout 04:16 15Ent 59:52 116 74:32 14 1 59:56 116Totals 83:08 179 93:15 189 79:08 1 6 4'APU s ran for approximately 14 minutes 47 seconds after main gear touchdow n.b Totals do not include 5 minutes 53 second s of operation during the launch abo rt.Each A PU co nsumed i8 Ibm of fuel during the launch abort operation.21


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Hydrau l i cs / Wat er Spray Bo l l er Subsyst em

The hydraul ics/WSB subsystem m et a ll requirements placed on the system; howeverseveral minor problems were noted.During prelaunch operat ions , nominal performance was observed except for out-of-specif icat ion in ternal leakage on W SB system 2 G N 2 regulator after opening the GN2isolation valve during the prelaunch ac tivities (Flight Problem S TS-68-V-0 6). Thef i rs t regulator leakage w as about 4 2 scan (redl ine l imit is 10 sccm ) over a 2 6-minuteper iod fol lowing the f i rs t isola tion valve op ening. The second leakage w asapproxima tely 73 sccm over a 28 -minute period just prior to launci i . The isolationvalves were closed when ever possible in accordance with nom inal procedures todecrea se the sensi t iv i ty of the G N 2 tanks to internal regulator leakage. Internalleakage has been observed in the pas t to be caused by a dam aged balance s temO-ring.The ascent operat ion of the hydraulics subsystem w as nom inal , and theper formance o f two o f the th ree WSB sys tems w as nomina l. WSB sys tem 3exhibi ted a 24.5 O F AP U lubr ication oi l overcool subsequent to spray s tar t . Thisovercool is bel ieved to have bee n caused by a s l ight freeze-up of the WSB spraybar.On-orb it operation of th e h yd rau licsM + SB s u b s ystem was n om in a l except for WSB 1G N 2 regulator which exhibi ted a low-pressure decay in regulator out le t pressurethrough the re l ie f va lve (F l ight Probl em S T S -68 -V -07) . T h e decay began at274:14: 3 5 G ,m. t . ( 01 : 03 : 19 M ET) and cont inued for the remainder of the f light .H ydraul ics WSB system 1 was used for FCS checkout; however , no spray coolingwas required because of the shor t run- t ime of the A PU (4 minutes 16.58 seconds) .T h e G N 2 i sola t ion valve was kept c losed dur ing the FC S checkout to prevent loss ofwater because the regula tor out le t p ressure decay m ay have been due to w ater leak .The pressure decay ed to 16.8 psia prior to entry; how ever, this W SB operatednominal ly throughout entry and landing.At 2 83:12:10 G .m.t. (10:00:54 M ET), the rudder channel 3 secondary dif ferentia lpressure required approximately 1 .96 seconds to increase to the fai lure-detect ionlevel (bypass) du r ing the posi t ive-st imulus por t ion of the secon dary-actuator checkin the FC S checkout procedure (Fl ight Problem ST S-68- V -11) . The channe l shou ldnormally bypass in approximately 120 ms. The channel bypassed nominally duringthe negat ive-st imu lus port ion of the test . Data review show ed a delay of1 .44 seconds on STS-59 , less than one second on STS-57 , l ess than 0 .25 secondon STS-54 , and 0 .15 second on ST S-49 . There were no delays apparen t on STS -47or STS-61 .

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During entry, the hydraulics subsystem performed satisfactorily. WSB system 1performed nom inally. WSB system 2 exhibited a maximum internal leakage ofapproximately 22 sccm af ter the G N 2 isolation valve w as opened for entry.The W SB 3 system 3 regulator pressure showed a rapid decay short ly af ter weight-on-whe els (WOW ), indicating a leak (Flight Problem STS -684-1 0). This WS B hadb een s tab le th rou gh ou t th e m iss ion . Th e G N 2 pressure dropped from 38.1 psia to19.8 psia in just over one hour. Water w as observed com ing from the ET um bilicaldoors and ce nterline hinge while sti ll on the runwa y. Total wa ter leakage in to the aftcompartment w as es t imated to be 88 lb (10.5 gal lons) . Approximately 0 .5 lb of w aterremained in the tank. The postflight inspection revealed that the WS B 3 b ottom andport s ide blankets were wet . System 3 was repressur ized by cycl ing the G N2isolation valve d uring troubleshooting to pinpoint the leak. The w ater leak wasisola ted to a crack 'n the WS B sy stem 3 A PU lubrication oil spray valve on the inlets ide . It has been determined that the crack resul ted f rom contam inant that wasintroduced into the system, and the contaminant produced corrosion.

E l ec tr i ca l Po wer D i s tr i but i on and Co ntro l 5u1bsys temThe performa nce of the electrical power distribution and control (EP DC ) subsystemwas nom inal throughout the m ission w ith no problems or anom alies identified in thedata. All data analyzed showe d nom inal vol tage and current s ignatures, and nospecified limits were violated during the m ission.

E n v i ro n m e n t a l C o n t r o l a n d L i f e S u t w o r t S y s t e mThe environmental control and l i fe support system (EC LS S) met a l l requirements ofthe miss ion in a sa t isfactory m anner .The act ive thermal control subsystem (A TC S) operat ion w as nominal throughout themission. After the FE S feedline heater reconfiguration to heater system 2 at278:15:15 G .m.t. (05:04:00 M ET), the FES feedline A high-load line temperaturewent off-scale high (>250 F) for near ly e ight hours (Fl ight Problem STS-684-05).The FE S feedl ine A accu mulator l ine temperature measurem ent had beenexperiencing erratic cycling during the off-scale high periods and had m aintainedtemperatures abo ve the nom inal thermostat control band. The heater on this l ine iscontrol led by the same thermostat as the heater on the high- load l ine , and i t isposs ib le that the hea ter sys tem 2 therm osta t i s loose . T h e off-scale high con dit ionwas also repeated for shorter periods (1 to 3 h ours), a s ignature that also occurredduring STS-59. The crew switched back to heater sys tem 1 a t 280:04:14 G .m.t(06:16:58 ME T) and a l l temperature condi t ions became nominal .The A TC S successful ly supported the payload cool ing requirements . by placing bothFreon coolant loops (FCLs) to the payload mod e a t 273:13:29 G.m .t.

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( 0 0 : 0 2 : 1 3 M E T ) . T h e F C L s w e r e r et u r n e d t o th e i n t er c h a n g e s m o d e a t284:06 :13 G . rn . t. (10 :18 :57 ME T ) .The rad ia tor co ldsoak prov ided cool ing dur ing en t ry th rough touchdow n p lus1 5 m i n u t e s w h e n a m m o n i a s y s t e m B , w h i c h u s e d t h e p r i m a r y ,'G P O c o n t ro l le r , w a sa c t iv a t e d . A m m o n i a s y s te m B w a s d e a c t i v a te d a f t e r 1 7 m i n u te s o f o p e r a t io n w h e ng r o u n d c o o l in g w a s c o n n e c t e d a n d p l a c ed i n o p e r a t i o n .T h e s u p p l y w a t e r a n d w a s te m a n a g e m e n t s y s t e m s p e r f o r m e d n o r m a l l y t h r o u g h o u tthe mission. Supply water was managed through the use of the FES and overboarddump systems. The supply water dump line temperature was maintained between66 and 100 O F w i th the ope ra t ion of the l ine hea te r . Three supply wa te r dum ps weremade at an average dump rate of 1.59 percent/minute (2.9 lb/min).Waste water was gathered at about the predicted rate. Four waste water dumpswere made at an average dump rate of 1.9 percent/minute (3.13 lb/min). The wastew a t e r d u m p l in e t e m p e r a t u r e w a s m a i n ta i n e d b e t w e e n 5 3 a n d 8 0 O F throughou t themission. The vacuum vent line temperature was maintained between 57 and 80 F,w h i l e t h e n o z z le t e m p e r a t u r e w a s m a i n t a in e d b e t w e e n 1 1 8 a n d 1 7 8 F .The w as te co ll ec t ion sys tem (W C S) pe r formed adequa te ly th roughout the mis s ion .The a tmo sphe r ic rev i t a li z a t ion sys tem (A RS ) pe r forman ce was nom ina l th roughout .the mis s ion wi th no prob lems or anom a l ie s iden t if i ed . DT O 664 - C ab inT e m p e r a t u r e S u r v e y w a s p e r f o r m e d w i th n o p r o b l em s .T he A IRS p ressu re co r1ro l sy s t em per fo rmed n om ina lly t h roughou t the dura t ion o fthe mission. During the redundant component check, the pressure controlconf igura t ion was sw i tched to the a l t e rna te sys tem. Bo th sys tems exhib i t ed norma loperation.

A f r ock Support Syst emUse of the airlock support system and components was not required because noext ravehicu lar ac t iv i ty (EVA ) w a s planned or required. The active system monitorpa rame te r s ind ica ted norma l ou tput s th roughout the d ura t ion o f the f l igh t .

S m o k e D e t e ct io n a n d F i r e S u p p r e ss io n S u b s y s te mT h e s m o k e d e t e c t io n s y s t e m s h o w e d n o i n d i c a ti o n s o f s m o k e g e n e r a t io n d u r in g t h eent i r e dura t ion of the f l igh t . Use of the f i r e supp re s s ion sy s tem w as not r equi red .

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Avionics and Software Staters

Du r ing en t ry , the pe r formance of the in tegra ted guidance and nav iga t ion sys tem wasnom ina l. E n t ry nav iga t ion sensor s a l l func t ioned nom i rmi ly , and the r e w ere nof a i lu re s or de se lec tions by RM . The re was no nav iga t ion m easurem ent da ta ed i ting .Drag m easurem en t p rocess ing s t a r ted a t 222K f t and ended a t 64 .9K ft . T A CA Nstat ion acquisi tion occurred at approxim ately 142 K f t wi th the cone -of -confusionspanning the 6 4 .9K f t to 8K f t r ange o f a l ti tude . A i r da ta t r ansduce r a s sembly(A DTA ) data incorporat ion s tar ted at approximately 77K 111and con t inued toapprox imate ly 15K f t . T he m ic rowave scann ing beam l and ing sys t em (M SB LS)processing in the na vigat ion f i lter was in it ia ted at ap proximately 15 K f t , and a l lm easurement r e s idua l s we re nom ina l . The pr imary av ionic s sof twa re sys tem-backup f l igh t sy s t em (PA SS-B FS) s t a t e vec to r compar i son in UV W co ord ina t esshow ed tha t bo th sys tems were pe r form ing and t r ack ing a s expec ted .W h i le f l y in g a d e s c e n d in g a p p r o a c h i n to E d w a r d s , D T O 2 5 1 - E n t r y A e r o d y n a m i cC on t ro l Sur faces T es t - A l te rna t e E levon Sch edu le - was succe ss fu ll y pe r fo rmed w i tha l l p rogramm ed t es t i npu t s (P T I s) sa t is f ac to r il y com ple t ed . At t he t r ans it ion toapproachi landing , DTO 2254 - Subson ic Aerodyn amics Ver i f ica t ion - wa ssa t is f ac tor ily com ple ted . Drag chute deploym ent was com ple ted pr ior to de ro ta t ioni n a c c o rd a n c e w i t h D T O 5 2 1 - O r b it e r D r a g C h u t e S y s t e m .A " B C E S T R G 3 M T U " m e s s a g e w a s a n n u n c ia t e d a t 2 7 9 : 1 3 :0 5 G - m . t.(06:01 :49 M ET ) . Thi s me ssage ind ica te s a prob lem in the se r ia l 1 /0 da ta pa thbe tween the MT U and the GPC , inc lud ing M DM FF 3 (F l igh t Prob lem ST S -68-V-04) .T he M T U bu i lt - in t e s t equ ipmen t (B IT E ) word w as nom ina l, t hus ind ica t ing no M T Uprob lems . A n VO re sa t and s t r ing 3 po r t ,node w ere pe r formed in an unsuccess fu la t t empt to c lea r the prob lem. Tw o go od accu mu la tor s s t i ll ex i sted , and th i s f a i lu red id no t impac t t he f l igh t o the r than the loss o f M T U redundancy . An M DM BIT ESta tus Read (BSR ) was pe r fo rme d a t 284 :06 :50 :36 G .m. t . (10 :19 :34 :36 M E T ) and i ts h o w e d a n o m i n a l v a l u e o f 0 0 0 0 . A n M D M B I T E T e s t w a s t h en p e r f or m e d a b o u t t w om inu tes l a t e r and i t a l so showed a nom ina l va lue o f AA A A 5555 ) . T h i s was fo l low edb y a s e c o n d M D M B S R a p p r o xi m a t e ly f i v e m i n u te s l a te r t h a t a g a in s h o w e d n o m i n a lvalues.The f l igh t cont ro l sys tem pe r formance w as sa t is f ac tory except for one i t em. A t283:12 :10 G.m . t. (10 :00 :54 M E T ) , t he rudder channe l 3 secondary d i f f e r en ti a lpre s sure r equi red approxim a te ly 1 .96 secon ds to inc rea se to the f a i lu re -de tec t ionleve l (bypass ) dur ing the p os i t ive - s t imu lus por t ion of the secon da ry-ac tua tor checkin the FCS ch eckout procedure (F l igh t P rob lem ST S-68-V-11) . Thi s prob lem i sd i scussed in the H ydraul i c s s ec t ion of th i s r epor t .The pe r form ance of the th ree h igh accuracy ine r ti a l nav iga t ion sys tem (H A INS )IM U s wa s ve ry sa t i s f ac to ry th roughou t t he p r e l aunch a c t iv it ie s and the f li gh t . T hepre f l igh t a l ignment gy rocom pass pe r formance w as except iona l w i th the l a rges t mean

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relative errors being -34 aroseconds. The l a rg es t m i s a li g nm ent m ea n co rrec t i o no bs erved du r i ng the s crub a nd the l a unch pre f l ig ht a l ig nm ents w a s 11 areseconds.O n ly on e u p l in k ad j u s tm e n t o f gyr o d r i f t an d t w o sm al l ad ju s t me n t s o f t h eac c e le r om e t e r s w e r e p e r for m e d d u r in g t h e f li gh t .T h e s t ar tr ac ke r s op e r at e d n om in a l ly w i th n o p r ob le m s id e n t if i e d .

Displays and Controls SubsystemA t approx ima te ly 263 :16 :30 G.m . t. (10 :05 :54 M E T ) , t he c r ew r epor t ed tha t t he t ensd ig i t on the Ku-band r ang e r a t e /az imuth d i sp l ay on pane l A2 was m al func t ion ing(F l igh t Prob lem ST S- 684-09). O nly the upper lef t l ight -emit t ing diode (LE D) wasi llumina ted . Wh en the l amp te s t was pe r formed, a l l LED s i llumina ted cor rec t ly . Thec r e w u s e d S P E C 2 0 1 f o r K u -b a n d s t o w i n g , w h ic h w a s c o m p l e t e d n o m i n a ll y .A t 283 :23 :46 G .m. t. (10 :12 :30 M E T ) , t he c r ew tu rned on the fo rward por t f lood l igh ta n d n u m e r o -3 c u r r e n t sp i k e s r a n g in g f r o m 9 t o 1 2 a m p e r e s d o w e r e n o t e d o n t h em i d p o w e r c o n t ro l a s se m b l y ( P G A ) m a i n A b u s . T h e s e s p ik e s a r e e v id e n c e o f ak n o w n a r c i n g p h e n o m e n o n . T h e l i g h t w a s , p o w e r e d off , and o ther l ights w e r eav a i l ab l e ; c on se q u e n t l y , th e lo s s of th is light d id not impact m ission operat ions.L. f i r ing conf igurat ion of the RC S to s t ra ight feed at 282 :13:20:44 G .m.t .(09 :02 :04 :44 M E T ) , t he c r ew r epor t ed tha t t he l e ft RC S 3 /4 /5 c ross f eed va lvet a lkback ( ind ica tor ) show ed ba rbe rpole w hen i t should hav e ind ica ted c losed . Thec rew tapp ed the pan e l and repor ted tha t the t a lkback ind ica t ion t r ans i tioned toclosed. The data indicate a clean, simultaneous closure of both the fuel and oxidizerva lves . Thi s condi t ion w as docum ented dur ing pre f l igh t ac t iv i t ie s and accepted a s afly-as-is condit ion.

Communications and Tracking SubsystemsThe com mu nica t ions and t r ack ing subsys tem p e r formed sa t i s fac tor i ly th rougho ut themis s ion . The S-ban d com m unica t ion l ink handove r f rom the W al lops I s l and grounds ta tion to the Tracking and D a ta Re lay (TD RS) sa te l li te dur ing a scent was n om ina l .Dur ing the p r e launch t ime- f rame a t 273 :07 :00 G.m. t ., T AC A N 2 locked on in rangebut d id no t lockon in bea r ing whi le on the uppe r an tenna and con f igured to KSC.W hen swi tched to the Pa t ri ck A FB T A CA N beacon , T AC A N 2 d id no t lock-on inb e a r in g o n t h e u p p e r a n t e n n a . T A C A N s 1 a n d 3 p e r f o rm e d n o m i n a l ly i n b o t h r an g eand bea r ing , and w hi le on the low er an tennas a l l t hr ee T A C A N s opera t ed nom ina lly .Data r ev iew and ana lys i s ind ica te s tha t the cause of the TAC A N 2 co ndi t ion w aspoor s igna l because of mui t ipa th a t the TA C A N 2 upp e r an tenna , com bined wi thT A CA N 2 hav ing more sens i ti v it y t o such cond i tions .

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A t 273:19 :54 G.m . t. (00 :08 :38 M E T ) , Ku-band channe l 2 da t a f rom an opera t ionsr ecorder dump w ere degraded (F l igh t Prob lem S T S-68-1-01 ) . Ku bared channe l 3was ac t ive a t the t ime wi th h igh-r a t e da ta f rom S IR-C and X-SA R. A t2 7 3 : 2 0 : 1 8 G . m . t . ( 0 0 : 0 9 :0 2 M E T ) , c h a n n e l 2 d a t a w e r e d u m p e d a g a i n w i t h n o m i n a lresults. Channel 3 was not active at that time. This appears to be a repeat of theanom a ly obse rved on th i s veh ic le w i th the same pay load dur ing the STS-59 m is s ion ,a n d t h a t a n o m a l y w a s c l o se d a s a n u n e x p l a i n e d a n o m a l y . T h e i m p a c t w a s m i n i m a ls i n c e c h a n n e l 2 o p e r a ti o n s r e co r d e r d u m p s w e r e a v o i d e d w h e n p a y l o a d d a t a w e r ebeing downlinked on channel 3. A t roubleshoot ing plan wa s developed p r ior to f l ightto a id in de te rm ining the cause of the appa ren t in te r fe rence . The Ku-b anddegrada t ion t roub le shoot ing procedu re was pe r formed a t 279 :18:20 G .m. t .(06:07:04 M ET ) . The da ta co l lec ted dur ing the t e s t showed tha t the s igna tureexpe r ienced dur ing STS-59 w as no t dupl ica ted . 'H ow eve r , da ta f rom W hi te SandsG r o u n d T e r m i n a l ( W S G T ) a n d d e lo g o f K u c h a n n e l s ta t u s fr o m N A S A G r o u n dTerminal (NGT) were obtained and analyzed to isolate possible causes. The dataana lys i s showe d tha t 12 of 15 da ta -dropou t inc ident s w e re d i r ec t ly r e la ted toope ra t ions r ecorde r t rack chang es , da ta gaps , o r conf i rme d A ppl ied Phys ic sLab ora tory r ecorde r prob lem s . Three inc ident s r evea led seve re degrada t ion inchann e l 2 (ope ra t ions r ecorde r ) da ta qua l ity w i th no usab le da ta , and the se couldnot be correlated with track changes or data gaps. Data analysis showed thatchanne l 3 con ta ined the p layback of S IR -C d a ta dur ing the se th ree spec if i c timeperiods when severe channel 2 degradation was observed. Channel 3 data werenot a f fec ted . A lso , a ll th ree ins tances we re on the TD RS -W es t us ing the 2 - southground equipm ent cha in for da ta process ing .Du ring the Orbi ter post f light crew debr ief ing, the crew repor ted co nt inuous er rat icr e a d o u t s o n th e d i s p la y p a n e l a n d c a t h o d e r a y t u b e s ( C R T s ) in S P E C 2 0 1 w h i lepe r forming the Ku-ban d s tow p rocedure s . The e r ra t ic r eadouts we re n o ted wh i le inthe s low s lew m ode (0 .4 0/sec). The crew had been trained to expect erratic readoutsin the fas t - s lew m ode (20 0 /sec), and therefore , though t that the s lew w as "defaul t ing"to the fast mode. The crew noted this erratic behavior three times. Ku-banda n t e n n a s t o w a g e w a s p e r f o rm e d d u r i n g a d a r k p a s s w i th o u t p a y l o a d b a y l ig h t s , sono v i sua l repor t o f the cond i t ion i s ava i l ab le . Da ta show tha t the c rew w as h i t ting thea lpha sof twa re s top , r e su l ting in a 360 degree w hip-a round at 20 degrees/second tor each the r eques ted pos i t ion . Da ta show tha t th i s condi t ion occur red f ive t imes .This s cena r io i s a nom ina l occur rence .

O p e r a ti o n a l I n s t ru m e n t a t io N M o d u l a r A u x i l ia r y D a t a S y s t e mA t approx ima te ly 282 :08 :50 G .m. t . (08 :21 :34 M E T ) , degraded da t a were no teddur ing p layback of the App l ied Phy s ic s Labo ra tory da ta on the pay load recorde r(Flight Problem STS-684-08). Track 2 had degraded data from the 68 to the100 p e rcent pos i t ion , t r ack 3 was deg raded f rom the 29 to the 68 pe rcent pos i t ion ,and track 4 was do aded from the 84 to the 100 percent position. The APL dataw e r e o n K u - b a n d 4 . j a n n e l 2 a n d S R L h i g h - ra t e d a ta w e r e o n K u - b a n d c h a n n e l 3

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during par t of these dum ps. On-orbi t t roubleshooting was performed using dif ferenttape direct ions (forwa rd and reverse) and du m p rat ios (1 to 1 and 16 to 1). Thist roubleshoot ing revealed thRt only t racks 1 and 5 -14 w ere usable for the remainderof the m ission.Du ring postlanding operations, operations recorder 2, track 8 w ould not dum p ineither the forward or reverse directions (Flight Problem ST S-68-V-12 ). The failurei nd i ca ti on was an unm odula t ed ca r .er . All other t racks dum ped (4 through 7 an d 9and 10 ). Troubleshooting at KSC verif ied a bad track 8. The operat ions recorderwil l be rem oved, repaired and re insta l led.

S t r u c t u r e s a n d M e c h a n i c a l S u b s y s t e m sThe s t ructures and m echanical subsystems performe d sat isfactor ily throughout them ission. The landing and braking data are show n in the table on the fol low ingp ag e .The drag nhute performance w as excel lent , and the deployment w as completed a tthe planned t ime in the O rbi ter rollout . As a resul t , only l ight braking w as needed tobr ing the vehicle to a s top. Test condi tion 4 of D TO 521-Orbi ter Drag C hute Systemwas completed with this landing.

I n t e g r a te d A e r o d y n a m i c s . H e a t i n g a n d T h e r m a l I n t e r f a ce sThe ascent and entry aerodynam ics were nominal wi th no problems, anom alies, orunexpected conditions identified in the data.During entry, all f ive PTIs required by DT O 25 1 Part 7 - Entry Aerodyn amic Co ntrolSurfaces Test - A l ternate Elevon Schedule were com pleted. A lso , DT O 25 4 Par t 4 -Subsonic Aerodynamics Verification was performed during the final approach. Allai leron and rudder inputs were as expected for this DTO . Likewise, DTO 52 1- OrbiterDrag C hute Sys tem per formance w as as expec ted .The integrated heat ing during ascent and entry was nom inal , based on the telemetryda ta and the p lume appearance . The en t ry aerodynam ic hea t ing was nom inal;how ever , postf l ight analysis and heat ing calcula tions are con t inuing as th is is wri t ten .The performance of the thermal interfaces was nominal with all temperatures remainingwithin limits, and there were no L CC violations.

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L a n d i n g a n d B r a k i n g P a r a m e t e r sFro mParameter th re shold , Speed, Sink rate , f t /sec Pi tch ra te ,

f t keas de secM a i n g e a r t o u c h d o w n 3 5 8 5 193.1 --1.0 NIANose gear touchdown 17 301 928 .4 N/A -4.4B rake in i t ia t ion speed 81 .5 kno t s (kegs)Brake-on t ime 34.0 secondsRol lou t d i s t ance 8,490 fee tRollout t ime 61.8 secondsR u n w a y 22 (Co n c re t e ) EA FBO rbi ter wei h t a t land in 2 2 1 , 5 7 1 l bPeak

Brake sensor pressure, B r a k e a s s e m b l y E nergy ,locat ion psia million ft-lbLef t -hand inboard 1 64 8 Left-ha. - ,d outboard 10 .05Lef t -hand inboa rd 3 5 2 8 Lef t -hand inboard 12 .54Lef t -hand outboa rd 2 5 4 0 R i h t - h a n d i n b o a r d 11 .45Lef t -hand outboa rd 4 5 5 2 Righ t -hand ou tboard 8 .60FU h t -hand inboard 1 5 88Ri g h t - h a n d i n b o a r d 3 4 8 0R i g h t - h a n d o u t b o a r d 2 4 2 0Fr igh t -hand ou tboard 4 4 4 4T h e r m a l C o n t r ol S u b s y s te m

The the rma l cont ro l subsys tem pe r forman ce was nom ina l .The F ES p r imary accum ula tor line A the rm os ta t cyc led e r

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STS-68 Space Shuttle Mission Report

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