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5

the failure mode in question was of such low probability that no change would be forthcoming.  Changes of this nature which fundamentally affect the way the crew has trained must be made as early as possible and only when absolutely necessary.  In this case the change could have been teleprinted up to the crew the day before with the supporting rationale.

Before TDRS became available for the flight, there was concern on the ground that the SBS spacecraft might not be activated in time for the payload community to see any data prior to LOS Hawaii.  As it occurred, the satellite was activated and on internal power approximately 11 minutes prior to deploy time.  It is the opinion of MS1 and MS2 that it is not realistic to expect that a satellite could be activated more quickly, and if a baseline fiture should be required at some future time, the 41-D timeline should be adopted as optimistic.

As a note of interest which could apply to future cargo configurations, it is the opinion of the 41-D crew that it would not have been possible to monitor the Telstar spin-up visually had the SYNCOM satellite not been deployed.  In this case, we would have probably requested to open the SBS sunshield to allow direct visual monitor of the Telstar deploy operations.

Finally, the 41-D crew felt comfortable with a day 1 deployment.  In particular, we did not feel rushed, and had there been a requirement, the crew felt that they could have deployed SBS on the previous orbit.  In fact, had a contingency required, the crew felt that it would have been feasible to deploy two satellies on consecutive orbits.

OAST-1

The OAST-1 payload consisted of an extendable solar array wing, dynamics measurement electronics, and a solar cell calibration experiment.  In addition, the closed circuit television (CCTV) system was specially configured to allow simultaneous video recording from up to four cameras for post-flight analysis of array movements.  The solar array was extended while in different Orbiter attitudes on flight days 3, 4, and 5.  Dynamics tests utilized preplanned sequences of vernier jet pulses input by the crew at specific times in an orbit.  Passive tests were also performed to measure solar cell characteristics.  Several orbits of a top-sun attitude were scheduled with the array retracted for the separate solar cell calibration experiment.  All aspects of OAST-1 payload performance were nominal.  The following comments are offered.

Preflight changes.  Shortly before the scrubbed launch, thermal considerations began to emerge which caused several revisions to the flight plan at that time.  Even after the scrub, there were more late developments, concerning not only thermal issues but also moon position effects.  The ensuing changes to the mission attitude profile and payload operations were being documented in the Flight Data File even as it was being packed for shipment to KSC.  Payloads should be held to the requirements of identifying any constraints and completing any analyses which might affect timelining no later than the Flight Operations Review so that a stable flight plan and mature procedures can be solidified early.

Real-time on-board planning.  In order to accommodate the worst-case situation in which array motion was excessive enough to prohibit Orbiter attitude