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Air Force Satellite Shows Off Rendezvous Skills

Orbiting Earth for sixmonths, the U.S. Air Force XSS-11 (Experimental Satellite System-11) hasachieved an early objective--to rendezvous with other space hardware.

The small, low-costspacecraft was developed by the U.S. Air Force Research Laboratory's (AFRL)Space Vehicles Directorate at Kirtland Air Force Base in New Mexico. The XSS-11is shaking out technology and techniques for future military space purposes, beit for in-space servicing and repair of other satellites to up-close inspectionof objects in space.

The XSS-11 was rocketed intospace on April 11 from Vandenberg Air Force Base, California atop an OrbitalSciences Minotaur booster.

Maneuvers to upper stage

XSS-11 has flown repeatrendezvous maneuvers with the Minotaur upper stage that deposited it intoorbit, reported Harold "Vern" Baker, AFRL's XSS-11 program manager. "Thesatellite is doing outstanding," and has accomplished "a significant milestone."

Baker told SPACE.com thatthe XSS-11 is carrying out "passively safe trajectories" to repeatedly reachthe Minotaur upper stage. The Air Force experimental spacecraft approached thespent stage, maneuvering to as close as about 1,640 feet (500 meters) distance.

"We do have some imagery" ofthe upper stage taken by XSS-11, Baker said. That data is still being reducedand reviewed, he added.

The up-close look-seeproduced no surprises, Baker said, but there was "a lot of excitement when ithappened."

XSS-11 is outdoing anearlier shakeout test satellite, the XSS-10. That spacecraft flew a 20-hourmission in January 2003, inspecting and navigating around the Delta 2 secondstage that placed XSS-10 into orbit.

Next objective

Baker said that the XSS-11may remain in its present phase of testing over the next 8 to 12 weeks beforecontrollers plan for the next rendezvous. Its next operation depends on the completionof its current work, and what space hardware is reachable given fuel efficientmaneuvers, Baker said.

"Our fuel consumption hasbeen extremely good," Baker explained. "We've used about 10 percent of our fuelso far" after being in orbit for six months, he said.

Baker said that thepropellant onboard the XSS-11 should allow the vehicle to accomplish itsmission. "We expect to go for another year," he explained.

Orbiting space hardware thatmight be reached by XSS-11 includes derelict rocket bodies and several oldsatellites. Selected objects are all dead or inactive property and U.S.-owned.

For example, XSS-11operators were considering a rendezvous in the near-term with an old Thor upperstage. "That was within the next three weeks, so we probably won't go see it.We'll wait for another one," Baker said.

Air Force spacetechnology

Baker said that XSS-11 isthe best satellite he's ever flown. The comment is made all the more sweetergiven the total project cost: $82 million, including launch, operations, thespacecraft itself, and all the ground control hardware, Baker noted.

Lockheed Martin SpaceSystems Company near Denver, Colorado is AFRL's structure, propulsion andsystems support contractor for XSS-11.

The groundwork for an XSS-12mission - still to be fully defined - is already in motion. Perhaps by year'send, Baker explained, the duties of such a follow-on satellite may be clear. Tofurther hone Air Force space technology, not all progress depends on XSS-typesatellites.

"We're a lab dedicated todeveloping technologies needed by the Air Force for future missions," Bakersaid. Those needs could mean anything, he said, from docking, servicing,inspection to imaging.

RoadRunner and DSX

One such project in theworks is RoadRunner, an experimental satellite that will have gone from conceptto launch ready within 18 months.

Loaded with hardware,RoadRunner equipment would collect radio, radar, and handheld communicationsignals. It would also tote a telescope to demonstrate low-cost, high-qualityphotography for use by war fighters in the field. This experimental satellitewould show off autonomous operations attributes using a sophisticated autopilotsystem.

Along with RoadRunner is theDemonstration and Science Experiments (DSX) satellite, once dubbed theDeployable Structures Experiment. Areas to be advanced by DSX involveconducting persistent global and tactical radar operations from medium Earthorbit; try out enhanced military satellite-based communication; and chart outhow future Department of Defense responsive satellite platforms can best beprotected from space weather phenomenon.

Both RoadRunner and DSX areAFRL efforts.

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