probably the best possibility for Europe to fly an inexpensive Powersat demonstrator on the Shuttle as this is an essentially European mission. Otherwise, opportunities to launch on other missions are likely to compete with the backlog of US pay loads awaiting launch. Even though the GAS CAP and Hitchhiker opportunities are for inexpensive pay loads, they must all nevertheless meet the Shuttle's strict and time-consuming safety specifications. The Payload Safety Review Process for Hitchhiker payloads are shown schematically in Figure 3.3-5. [16] Importantly, the time needed for the safety review process is lengthy. For Hitchhiker users, for example, the safety review process begins some 18-24 months prior to the target launch date, with the review being completed just prior to launch with the Final Safety Inspection. What this means, in summary, is that the design standard of the Powersat demonstrator must be clearly defined nearly 2 years in advance of the launch date. This time evidently conflicts with the proposed short-schedule/inexpensive nature of a Powersat experiment. 3.4 Other Possible Launch Opportunities 3.4.1 Astro-SPAS The Shuttle has been used on a number of occasions to deploy and recover large satellites with its remote manipulator system (RMS). Such satellites co-orbit with the Shuttle Orbiter at distances of up to several hundred kilometres and durations ranging from several hours to days. After this period, such satellites are collected by the RMS, re-installed back into the payload bay and returned to Earth for reuse on a later mission. The very first satellite used for this purpose was built by DASA-MBB/ERNO for the German space authorities and was designated SPAS-01 (Shuttle PAllet Satellite). This mission occurred on Shuttle flight STS-7 in June 1983. Two other SPAS missions have
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