'Virtual satellites': scientists pursue flexible, adaptable space systems.

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ANAHEIM, Calif. -- The Defense Advanced Research Projects Agency is predicting that in the future "virtual satellites" circling the globe will peer down on enemy forces.

Instead of one expensive 10,000-pound spacecraft, the spy camera will float alone, unattached to other components. The onboard processor and communications node, for example, will orbit nearby and the three building blocks in this system will be linked wirelessly.

The System F6 program--future fast, flexible, fractionated, free-flying spacecraft united by information exchange--would allow the Air Force or the National Reconnaissance Office to easily swap out outdated or broken components.

"Flexibility and the technology that enables it is the cornerstone of DARPA's vision of a new space architecture," Owen Brown, a program manager in the agency's virtual space office, said at the DARPATech conference.

Founded 50 years ago in response to the Soviet Union's launch of the Sputnik satellite, DARPA was a key player in creating today's U.S. military space architecture. Now the agency wants to tear that structure down and create new paradigms for space-based systems.

The key word, project managers stressed, is "flexibility."

Today's giant military spacecraft take anywhere from five to 10 years to complete the development cycle. As they are being built, technology advances, making some of their components outdated as soon as they reach orbit. To prevent catastrophic failure in orbit, redundancy must be built in, which adds weight, space and cost to the system.

These so-called monolithic spacecraft are vulnerable to launch failures, software engineering bugs or component malfunction that could set a program back by billions of dollars and years of development, Brown said.

Such satellites are "configured to solve tomorrow's problems using yesterday's technologies," he added.

The advantages of the F6 program are many, he asserted.

Program managers could change out software or hardware anytime during the spacecraft's lifecycle by sending up a smaller, less expensive replacement. A spy satellite could be changed in orbit to a communication satellite by adding a new node. It would also alleviate the "engineering nightmare" of having multiple sensing payloads on one spacecraft, Brown said.

The F6 concept is one of many programs in the revitalized virtual space office. After the Commission to Assess United States National Security Space Management and Organization in 2001 highlighted the vulnerability of U.S. space assets, DARPA refocused its efforts on its space program.

The commission recommended that the U.S. military and the agency invest in cutting edge space concepts. DARPA has responded with a $400 million annual space budget, said Steven Walker, deputy director of the tactical technology office and head of the virtual space office.

On Jan. 11, six years to the day after the commission released its report, China used a rocket to destroy one of its own spacecraft. The anti-satellite demonstration further reinforced the need to create "flexible" space systems, Walker said.

"Like Sputnik, this action should serve as a wake-up call," he said.

The virtual space program has five divisions: access infrastructure, where the F6 program resides; space situational awareness; mission protection; and, space-based support to the war fighter, which seeks to better tie space assets to soldiers and commanders on the ground.

The fifth is a classified program that is called "space mission denial." Walker declined to give details on this division, but the name suggests a program designed to neutralize enemy spacecraft or launching systems.

The F6 program fits into a larger concept that is known as operationally responsive space. One of the U.S. Strategic Command program's goals is to create satellites that can be built and launched within days or weeks, rather than months or years. The loss of key spacecraft due to attack, space weather or malfunction, makes the U.S. military vulnerable. Critics have called its dependence on space-based assets its Achilles heel.

The Air Force and Stratcom continue to work on their own concepts for operationally responsive space. They envision launching "plug-and-play" satellites readily assembled from components taken "off the shelf." If a communications satellite went down, for example, technicians could assemble a replacement quickly.

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The giant, expensive spacecraft of today aren't going away, Brown said, but such concepts may take small satellite programs "out of the boutique and into the mainstream."

Two DARPA programs designed to support responsive and flexible space systems have already come to fruition, Walker pointed out.

In June and July, the orbital express program demonstrated the ability of a spacecraft to carry out in-flight servicing. The Boeing-built spacecraft autonomously refueled a second satellite and swapped out its batteries and computer.

The DARPA/Air Force Falcon small launch vehicle program is attempting to make sending satellites less expensive, more reliable and to reduce the time needed to prepare for launch.

For concepts such as F6 or the rapid deployment of plug-and-play satellites, launch remains the central stumbling block. Apart from the complexity of finding slots on U.S.-based spaceports, the per-pound price of launch remains high.

Brown said he often hears criticism that launching small satellites is not cost effective. The per-pound price tag rises exponentially when there is only one small satellite or one node, as would be found in the F-6 program.

It's not the cost, but the value, Brown noted. Sending a letter by express mail across the world costs a premium, he argued, but the high price is weighed against the benefits of getting it there quicker.

"Cost per pound is a flawed metric ... There is a value to timeliness," he added.

Air Force Lt. Col. Fred Kennedy, protection program manager, said one solution might be the tiny independent coordinating spacecraft (TICS) program.

Satellites weighing as little as 10 pounds could be launched from a tactical munition similar to an AGM-88 high-speed anti-radiation missile, which is fired from jet fighters.

If a U.S. military spacecraft were threatened by a hostile satellite in space, a jet could be scrambled and subsequently launch a low-Earth TICS.

It would be simple to load and launch, and nearly impossible for an adversary to detect the operation, unlike major launch pads, which are closely watched, he said.

TICS has about a 50-50 chance of succeeding within the next five years, he predicted. The mico-electronics revolution is making it possible to create the small satellites required for such concepts, he noted.

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