 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] SMS:B27715       ]
 ]   LINDA IVERS      ]    BFS PROGRAM NOTE         ] DR: 108799       ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE: 5/19/93    ]
 ]  RID/ 922-4858     ]      RELEASE NOTE ( )       ]                  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ]            OI22 & SUBS        ]  CREW (X)  GROUND ( )  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]           MAJOR SOFTWARE AREA:            ] OPS MODES AFFECTED: 3   ]
 ]BSL( ) BSS( ) GNC(X) SEQ( ) SM/SP( ) IPL( )]                         ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: GUID                                             ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: MG038104 / 3.2.3.1.10.10                       ]
 ]_____________________________________________________________________]
 ] TITLE: PASS AND BFS HAVE DIFFERENT BURN SOLUTIONS                   ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION: DURING OPS 3 DEORBIT BURNS, BFS ESTIMATE OF VEHICLE    ]
 ] MASS WILL DIVERGE FROM PASS. BFS WILL NOT DECREMENT ENOUGH MASS     ]
 ] CYCLE TO CYCLE AND WILL LINEARLY DIVERGE FROM THE PASS MASS VALUE.  ]
 ] THE DIVERGENCE IS APPROXIMATELY .28 LB/SEC OF BURN FOR THE OMS      ]
 ] BURNS. STS-57 DEORBIT BURN WAS 366 SEC. LONG AND THE MASS DIFFERENCE]
 ] WAS 103 LB., BFS ENDING HIGHER THAN PASS. FOR FUEL WASTING BURNS,   ]
 ] BFS IN LISTEN MODE WILL SHOW VGO AND TGO RESIDUALS ON THE MNVR DIS- ]
 ] PLAY. STS-57 DEORBIT BURN MASS DIVERGENCE RESULTED IN 3 FT/SEC      ]
 ] RESIDUAL VGO AND 5 SECONDS OF RESIDUAL TGO. FOR BFS ENGAGED, THESE  ]
 ] RESIDUALS RESULT IN A SLIGHTLY LONGER BURN THAN PASS WOULD COMMAND. ]
 ] THE ADDITIONAL DELTA VELOCITY WILL BE IN THE OUT-OF-PLANE DIRECTION.]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] USER RESPONSE: IF FUEL WASTING IS NOT DESIRED, ITEM 18 PRPLT ON THE ]
 ] MNVR DISPLAY CAN BE ENTERED AS A ZERO WHICH WILL ELIMINATE THE VGO  ]
 ] AND TGO RESIDUALS. THE MASS DIFFERENCE WILL STILL BE SEEN ON THE    ]
 ] BFS MNVR DISPLAY. THIS DIFFERENCE IS EXPECTED TO BE VERY SMALL AT   ]
 ] APPROXIMATELY 0.05% OF TOTAL VEHICLE WEIGHT. STS-57 2 OMS DEORBIT   ]
 ] BURN WAS 14,000 LBS OF PROPELLANT AND THE TOTAL DIVERGENCE SEEN     ]
 ] WAS 103 LBS. BETWEEN PASS AND BFS. THE MASS DIVERGENCE SHOULD NOT   ]
 ] HAVE ANY ADVERSE AFFECTS ON ENTRY GUIDANCE.                         ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]RI: <S> J. AGRES          DATE 05/25/93]                             ]
 ]    --------------------      ---------]                             ]
 ]FDSD:   W. R. PRUETT      DATE 06/29/93]                             ]
 ]     -------------------      ---------] DARRELL E. STAMPER 06/30/93 ]
 ]PF MGR:  GENE MCSWAIN     DATE 06/29/93]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_____________________________________________________________________]
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