Cost-conscious space planners are studying the concept of orbiting ''carpools'' to make more efficient use of near-earth space. Here a leading space engineer explains how this may transform humanity's use of this new frontier.
Many of the satellites that go into low-earth orbit have common needs for such things as electric power or temperature control. Consequently, a share-the-ride era is emerging in space.
The interest of NASA (National Aeronautics and Space Administration) in more economical space operations has spawned the concept of large, multi-use facilities in low earth orbit called space platforms. A number of suggested designs are now being studied by McDonnell Douglas, under contract to Marshall Space Flight Center. Unmanned as well as manned platforms are planned; both will be ''plugged'' into a new, common utility-provision vehicle, a boxlike structure with large winglike solar panels and radiators that will provide 12-25 kw of solar-derived power, heat rejection, data handling, a ground communications link , attitude control, and orbit-reboost propulsion.
The multi-use facilities will orbit many payloads (in cost-effective, ''carpool'' fashion) both for scientific and commercial applications. The facility will be delivered into orbit in sections, assembled and activated with shuttle support, and then visited on a three-month cycle. The platforms are designed for easy loading and unloading. The periodic shuttle visits will allow crews to exchange payloads, as well as modifying, maintaining, or replenishing those on board.
The unmanned platform version planned for late in this decade will initially consist of a central utility vehicle with three short arms. Here payloads can be mounted and rotated independently to serve the three different viewing objectives of solar, astronomical, and earth-oriented instruments and their respective scientists at the consoles in the Payload Operations Control Center on earth. Ultimately, scientists hope to replace the three initial short arms with 12-meter ones to accommodate the much larger telescopes and antennas planned by NASA for later years.