May 19 2007
From The Space Library
Orbital Express successfully captured the ASTRO servicing satellite, and its client spacecraft NextSat, after the two spacecraft had flown apart for nearly eight days. ASTRO’s primary sensor flight computer AC-2 had failed during a test on 11 May, causing the craft to lose its relative navigation. During the test, the pair of craft had undocked and separated as planned, moving apart to a distance of 10 meters (33 feet). After the failure of its AC-2 computer, ASTRO had behaved according to the protocol of its programmed fault-protection software, flying 120 meters (394 feet) away from NextSat to avoid inadvertently colliding with the satellite. However, thereafter, ASTRO had drifted approximately 6 kilometers (3.7 miles) away from NextSat, requiring ground observers’ intervention to help the two craft remate successfully. DARPA planned to conduct a technical review of ASTRO’s sensor- and navigation-performance lessons and to conduct an investigation into the cause of the AC-2’s failure. The technical review would assist DARPA in planning the remaining set of Orbital Express demonstration activities, scheduled for the following weeks.
U.S. Defense Advanced Research Projects Agency, “Orbital Express Spacecraft Successfully Rendezvous, Remate,” news release, 21 May 2007, http://www.DARPA.mil/news/2007/oe_remate.pdf (accessed 6 April 2010); Kelly Young, “Estranged Satellite Pair Reunited at Last,” New Scientist, 21 May 2007; Stephen Clark, “Computer Problem Interrupts Satellite Servicing Demo,” Spaceflight Now, 15 May 2007.
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