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 |  | X Satellites Push Design Envelope
By Frank Sietzen, Jr.
Special to SPACE.com
posted: 07:05 am ET
27 September 2000
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WASHINGTON -- A new generation of experimental satellites that fly in formation and maneuver in space are about to emerge from the drawing boards of Air Force engineers. The experimental craft, called "X-satellites" after the X-rocket planes of the 1940s, 50s and 60s, may start test flights as soon as next year if approved in the Pentagon's budget.
The radical craft may push the envelope of space designs and establish fleets of small satellites that can be quickly deployed on a variety of military missions. Even NASA is involved in the planning for the X-craft, since their designs may have many uses.
"These are truly 'Concept Cars for Space' -- things that might migrate someday as systems for the future," said Christine M. Anderson, Director for Space Vehicles at the U.S. Air Force Research Laboratory (AFRL) near Albuquerque, New Mexico.
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The X-40A Space Maneuverable Vehicle has been tested in atmosphere for its ability to be brought down and landed remotely. Watch the video. |
The concepts now under final design and study include:
- Solar-powered transfer vehicles that can deliver multiple payloads while shifting their orbits.
- On-orbit space platforms that serve as space gas stations.
- Maneuvering satellites that will be able to pull up next to other spacecraft for a check out, all while orbiting earth at 17,500 miles (28,165 kilometers) per hour.
Anderson said that new designs for ultra-efficient rocket engines, lightweight structures that can slash the cost of putting payloads into orbit and energy-producing solar cells that can be "cut from a roll like carpet" are on military planner's drawing boards now at the AFRL.
Partners in the research work include NASA, the National Reconnaissance Office (NRO) and the Defense Advanced Research Projects Agency (DARPA). U.S. Navy space planners are also interested in the results from the test flights.
"Different technologies are important in addressing military requirements," Anderson explained. "These are areas that we are currently investigating, but not every agency is interested in every technology," she added. Anderson said that NASA was interested in technologies that could assist deep-space missions, while the Air Force was interested in directed-energy weapons.
And unlike the X-plane projects of past decades, cost is a major consideration in the fielding of the X-satellites. "We're not only attacking performance but also affordability," Anderson said. "We want to make sure that the technology will be manufacturable in an affordable way."
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Those technologies may seem pretty far out. Among those under study are a form of "smart skin" for future satellites where Anderson said "you would build-in power and control within the structure itself." If a satellite were damaged, it's "smart skin" would relay signals around the injury to other parts of the craft.
"Someday you might be able to service while on-orbit for replacing modules and other systems," she suggested. Other versions of the craft could serve as orbiting gas stations for military spaceplanes or other satellites stationed in space.
New generations of space computers and guidance systems are also being designed that are completely autonomous, meaning they will not need humans to control their flight from the ground.
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Satellite clusters can be used to cover larger areas in orbit with a group of small craft. |
And even more radical is the notion of fleets of microsatellites that orbit in clusters but act as one craft. "These clusters of co-orbiting microsatellites could perform a mission together, flying a very tight formation while orbiting," Anderson said. "You'd command them as a cluster, and they would figure out themselves how to do what you wanted them to do."
These craft would also be fully modular, meaning that different experiments or sensors could be swapped out rapidly when their missions changed. "We'd fly them in groups of three making a 16-satellite cluster," she explained. Along with the military and NASA, several universities were working on the technology that would be needed for formation flying.
Among the X-satellites on the drawing boards are:
An experimental satellite to demonstrate the ability to maneuver in space and park next to another satellite. While flying nearby, the craft could do inspections, imaging or look for damage on the other vehicle. The first XSS-10 test flight would be a 24-hour mission, with NASA, the Naval Research Lab and Lawrence Livermore Laboratory as partners. Hardware was in testing now, Anderson said, with a first flight in 2001 possible.
A space-superiority testbed. The satellite would demonstrate advanced orbital maneuvers and station keeping. Space surveillance of objects is a key goal of the test. "We want that one to have situational awareness in space," Anderson said. That would allow the craft to know if it was under jamming or laser attack. "We're developing new sensors for that." First test flight in 2004 possible.
The first orbital test of the cluster-orbiting concept. Batches of microsatellites would be launched and would fly in formation for a brief period to validate the idea. No date yet for the first space test flights.
In addition to the test satellites, Anderson said the AFRL was interested in five broad areas of military space research. These included space power, hyper-spectral imagery for Earth remote sensing, microsat technology in general, space communications breakthroughs and building large, deployable optical systems in space.
"X-vehicles are really crucial to space technology," Anderson said. "We are developing a feel for where commercial industry fits into our plans."
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