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

The small, low-cost spacecraft 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-11 is shaking out technology and techniques for future military space purposes, be it for in-space servicing and repair of other satellites to up-close inspection of objects in space.

The XSS-11 was rocketed into space on April 11 from Vandenberg Air Force Base, California atop an Orbital Sciences Minotaur booster.

Maneuvers to upper stage

XSS-11 has flown repeat rendezvous maneuvers with the Minotaur upper stage that deposited it into orbit, reported Harold "Vern" Baker, AFRL's XSS-11 program manager. "The satellite is doing outstanding," and has accomplished "a significant milestone."

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

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

The up-close look-see produced no surprises, Baker said, but there was "a lot of excitement when it happened."

XSS-11 is outdoing an earlier shakeout test satellite, the XSS-10. That spacecraft flew a 20-hour mission in January 2003, inspecting and navigating around the Delta 2 second stage that placed XSS-10 into orbit.

Next objective

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

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

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

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

For example, XSS-11 operators were considering a rendezvous in the near-term with an old Thor upper stage. "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 space technology

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

Lockheed Martin Space Systems Company near Denver, Colorado is AFRL's structure, propulsion and systems support contractor for XSS-11.

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

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

RoadRunner and DSX

One such project in the works is RoadRunner, an experimental satellite that will have gone from concept to launch ready within 18 months.

Loaded with hardware, RoadRunner equipment would collect radio, radar, and handheld communication signals. It would also tote a telescope to demonstrate low-cost, high-quality photography for use by war fighters in the field. This experimental satellite would show off autonomous operations attributes using a sophisticated autopilot system.

Along with RoadRunner is the Demonstration and Science Experiments (DSX) satellite, once dubbed the Deployable Structures Experiment. Areas to be advanced by DSX involve conducting persistent global and tactical radar operations from medium Earth orbit; try out enhanced military satellite-based communication; and chart out how future Department of Defense responsive satellite platforms can best be protected from space weather phenomenon.

Both RoadRunner and DSX are AFRL efforts.