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cargo bay, two on each of the forward and aft bulkheads, on both the port and starboard sides. These locations are designed to provide clear views of the SRMS.

The Data Acquisition Cameras (DACs) were on board for the purpose of SRMS verification and were used for STS2, 3 and 4 only. The DAC system consists of six 16 mm movie cameras which are mounted in groups of three on the forward and aft bulkhead. Photogrammetric analysis of the DAC film is used to provide data on the SRMS dynamics and position relative to a reference point on the Orbiter. Actual positioning accuracy, position hold stability and stopping distance can then be measured independent of the OI.

3.4 SRMS FLIGHT SUMMARIES

The first five flights, up to STS-8, are regarded as test flights for the SRMS, although the SRMS was considered operational after the STS-4 mission.

STS-2 was the first flight of the SRMS and consequently was its most important flight. Unloaded performance was demonstrated in all of its operating modes. Loaded performance of the SRMS was first tested on STS-3 with the Plasma Diagnostics Package (PDP) payload. In addition, unloaded testing of the arm continued. On STS-4 the unloaded testing was completed, and a further demonstration of lightly loaded arm operation with the Induced Environment Contamination Monitor (IECM) payload was carried out. The payload retrieval performance of the SRMS was demonstrated on STS-7 when the Shuttle Pallet Satellite (SPAS-01) payload was grappled by the SRMS while in the shuttle cargo bay, released and later retrieved by the arm. Also, the payload deployment capability of the SRMS was demonstrated by the releasing of SPAS-01 with a low tip-off rate, which is desired to ensure the stability of the payload after release. The contingency operation of the SRMS was demonstrated by a Direct Drive Berthing and Unberthing as well as a Single Drive track and capture of the free-flying SPAS-01 payload. The STS-8 mission completed the SRMS testing with the PFTA payload. However, SRMS flights subsequent to STS-8 will continue to provide further data on the SRMS on-orbit performance and the SRMS performance verification will go on. Figures 3-1 and 3-2 show the SRMS unloaded on STS-2, and loaded with the PDP on STS-3.

Use of the SRMS on 41-B was mainly a rehearsal for the satellite repair flight 41-C. The SRMS was used for the first time as a workstation by an EVA astronaut riding on a Manned Foot Restraint (MFR) attached to the arm (Figure 3-3).

Mission 41-C marked a highlight in the orbital flight of the SRMS where the largest payload to date, Long Duration Exposure Facility (LDEF), (Figure 3-4)



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