small-scale production stage, power requirements will have to be increased to provide flexibility and extend on-orbit stay time. A survey of organizations that are engaged in these activities indicates that they will be increasingly constrained by power supply limitations. The power requirements in future space shuttle missions starting in 1989 are projected to be in the 10-kWe range, and they are expected to grow to the 30- and 40-kWc range by 1996. Associated with these increased power requirements is also the need to reject to space the heat generated by the power used by the various facilities. There is only a limited capability for heat rejection on the shuttle beyond the space radiators that utilize the cargo-bay doors for heat rejection purposes. These will be inadequate to meet the needs of significantly greater heat rejection requirements as power use increases. The limitations on shuttle power availability have been recognized, and the concept of a power extension package to generate up to 25 kWe has been considered, but not implemented. The space shuttle's ability both to perform various tasks in orbit requiring significant power and to reject heat is partly limited by landing weight constraints. In addition, launching a powerplant that is integral to the shuttle will increase costs, as the payload presented by the power plant would reduce the volume and mass available for other shuttle payloads. An alternative approach would be to utilize a free-flying powerplant, consisting of solar cell arrays, space radiators, storage batteries, power conditioning equipment, propulsion system and avionics, permanently placed in low-Earth orbit and capable of effecting a rendezvous with the space shuttle. Such a space powerplant (Powercraft) would dock with the space shuttle and supply industrial-type power to users and reject heat from space shuttle processes and equipment. The Powercraft could enhance the shuttle's ability to support in-orbit activities by providing: • increased availability of power to meet user requirements; • increased capability to reject heat to space; • extended mission duration by reducing the power demand on the fuel cells, and • productive use of on-board volume and mass for shuttle payloads. The Powercraft may not have to meet all the requirements imposed on man-rated systems pertaining to critical design, materials, and reliability criteria, resulting in decreased cost. Its design can be based on the technologies developed for a multimission spacecraft system that has already been demonstrated in the Solar-max and Landsat missions. The Powercraft could also supply supplemental power to free-flying platforms that would be placed in low-Earth orbits, such as the Industrial Space Facility. Space Station A permanently manned space station will permit a range of activities to be performed in a microgravity environment over an extended period of time-one that cannot be achieved with a space shuttle. In addition, a space station will provide routine, economical, and flexible access to Earth orbits by manned and robotic systems; permit routine checkout, refuelling, repairing, and upgrading of unmanned, and manned space platforms, space laboratories and various satellites; provide facilities for the assembly and construction of projects in space; and facilitate space debris removal when methods to reduce the hazards of such debris have been developed. The prerequisite for these activities will be the availability of adequate power in
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