The Defense Advanced Research Projects Agency (DARPA) last week announced the Phoenix program to "develop technologies to cooperatively harvest and re-use valuable components from retired, nonworking satellites in GEO and demonstrate the ability to create new space systems at greatly reduced cost." There is a lot of work that needs to be done, but as DARPA Director Regina E. Dugan points out, "If this program is successful, space debris becomes space resource."
David Barnhart, DARPA program manager, explained some of the complications. "Satellites in GEO are not designed to be disassembled or repaired, so it's not a matter of simply removing some nuts and bolts. This requires new remote imaging and robotics technology and special tools to grip, cut, and modify complex systems, since existing joints are usually molded or welded. Another challenge is developing new remote operating procedures to hold two parts together so a third robotic 'hand' can join them with a third part, such as a fastener, all in zero gravity. For a person operating such robotics, the complexity is similar to trying to assemble via remote control multiple Legos at the same time while looking through a telescope."
DARPA is seeking expertise from "international and non-traditional space communities" to make this possible. DARPA said Phoenix "specifically seeks technologies for developing a new class of small 'satlets,' or nanosatellites, which can be sent more economically to the GEO region through existing ride-along services with commercial satellite launches and then robotically attached to the antenna of a nonfunctional cooperating satellite to essentially create a new space system."
The 'satlets' would be deployed using a to-be-designed payload delivery system or "PODS" and be housed in a tender in geostationary orbit. They would communicate with each other and be controlled through a master satellite such as DARPA's System F6. DARPA describes it this way, "Once the tender arrives on-orbit, the PODS would be released from its ride-along host and linked with the tender to become part of the satellite servicing station's 'tool belt.' The tender plans to be equipped with grasping mechanical arms and remote vision systems to remove components and satlets from the PODS using unique space tools to be developed in the program."
The first keystone mission of the Phoenix program is planned for 2015 "to demonstrate harvesting an existing, cooperative, retired satellite aperture, by separating it from the host non-working satellite using on-orbit grappling tools controlled remotely from earth. The aperture will then be reconfigured into a 'new' free-flying space system and operated independently to demonstrate the concept of space 're-use.'"
Considering the problems we've seen with antennas and solar arrays that don't deploy properly from satellites once they are in orbit, it appears even a simple system could from benefit some of the estimated more than $300 billion worth of satellites in geosynchronous orbit when they don't work properly. For the military, it could also provide a way to disable enemies' satellites without creating a belt of space junk that would pose a danger to friendly commercial and military satellites when their orbits intersect.
