A robot that can refuel and service America's spy satellites while they are in orbit is being developed by Department of Defense researchers. The new system could extend a satellite's life many times over, as it would no longer drop out of orbit and burn up once its fuel was all used.
The robot refueller, dubbed the autonomous space transporter and robotic orbiter (ASTRO), will shuttle back and forth between the spy satellite and fuel dumps stationed in holding orbits, says David Whelan, director of the tactical technology office at the Defense Advanced Research Projects Agency (DARPA).
With today's satellites, it is easy for an enemy to predict the craft's position, unless it changes course. But course changes use up the satellite's limited supply of hydrazine fuel and shorten its life. With a steady supply of fuel available to their satellites, controllers will be able to manoeuvre them at will, making their orbits more difficult to predict.
The development of ASTRO would revolutionise satellite operators' attitudes. "If an aeroplane runs out of fuel you don't throw it away," says Charles Miller of Constellation Services International in Dayton, Ohio. And yet, he says, that is precisely what happens with satellites costing as much as $1 billion apiece.
Miller believes a refuelling infrastructure is inevitable. His company has been set up to develop a satellite retrieval and repair service along similar lines for commercial telecoms and broadcasting satellites. The DARPA programme will rely on future military satellites being fitted with docking stations that allow them to be refuelled.
DARPA has secured $5 million to begin designing ASTRO, and expects to commission aerospace contractors to start building prototypes next year. By building satellites with modular electronics systems, the robot could also be used to replace faulty or outdated on-board systems.
Author: Duncan Graham-Rowe
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