The Defense Advanced Research Projects Agency (DARPA), a high-tech arm of the Pentagon, is working to develop a prototype system for refueling and upgrading spy satellites while in orbit. The project, called Orbital Express, could have implications for a broad range of space activities, military and civilian.
The goal is to move away from "the inflexibility and risk intolerance that were traditionally associated with our intelligence systems," says David Whelan, director of DARPA's tactical technology office. Whelan notes that the maneuverability of spy satellites is limited by their on-board fuel supplies, and that their electronics may become obsolescent while in orbit.
The Orbital Express project could lead to a "new infrastructure," says Whelan. For example, a robotic vehicle may shuttle between satellites and orbiting fuel depots. Such a vehicle has been dubbed ASTRO, for "autonomous space transporter and robotic orbiter." The project also seeks to develop a "standard design" for reconnaissance satellites so that old components can be replaced and upgraded.
DARPA has obtained $5 million in the federal budget for the year 2000 and is discussing design ideas with aerospace contractors. The program's costs for subsequent years have yet to be determined. The agency hopes to develop prototype technologies by around 2004, and may have working systems in place by 2010.
The project also may lead to new types of launch vehicles -- possibly "lower-performance hybrid or gun-launch technologies," says Whelan. Riskier launches may be acceptable when the payloads consist only of replacement parts, not full satellites.
Such launch vehicles, and other technologies resulting from the program, may be useful in civilian space exploration and commercial space projects, Whelan believes. He compares the Orbital Express project to the Interstate Highway System which was initiated with military funding, but has since become an indispensable mode of civilian transportation.
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