4 October 2006
|A patent recently issued to an
upstart space entrepreneur could be another sign that stealth satellites
are real — not vestiges of the previous millennium’s battles.
In late 2004, right about the time that some U.S. lawmakers publicly unveiled a previously classified $9.5 billion program to build satellites that orbit the Earth undetected from the ground, Robert Bigelow, hotel entrepreneur and founder of Bigelow Aerospace, submitted a patent application for a satellite that proposed to do just that.
Bigelow’s patent, filed in November 2004 and approved a year later, follows a dozen or so previously filed inventions back to the early 1960s. Each outlined methods that could reduce or eliminate the optical and radar signatures that could be used to track, identify and determine the orbital parameters of a satellite from the ground.
If the essentials of an orbit are obtained — potentially by low-cost, easily obtainable methods and equipment — an opponent can either hide above-ground activities during the reconnaissance satellite’s pass or possibly target the space vehicle with anti-satellite weapons. By all indications, the U.S. has launched and operated at least two such satellites in the post-Cold War era for photo reconnaissance or signal intelligence, one in 1990 and the other in 1999.
Bigelow’s invention, called an inflatable satellite bus, appears to be identical in construction to the company’s Genesis I spacecraft, which was launched July 12 by an ISC Kosmotras Dnepr rocket into a 550-kilometer near-circular orbit with 64-degree inclination.
The patent reveals that the shell, or outer surface of the inflatable portion of the vehicle, “can have radar stealth capabilities. This could include using radar absorbing materials and/or geometrics to reflect radar waves at angles that make detection of the craft difficult.” The patent goes on to say that shell could be “colored as to make visual detection more difficult.”
A former CIA analyst, Allen Thomson, included the patent in his latest Stealth Satellite Sourcebook, a document hosted on the Web site of the Federation of American Scientists. “I guess the main substantive reason I [included the patent] is that it shows the idea of satellite stealth is still in the air and is being used as a selling point,” he said in an e-mail response to questions from C4ISR Journal.
Given the secretive nature of stealth programs — the Defense Advanced Research Projects Agency, Boeing, Lockheed Martin, Bigelow Aerospace and other satellite builders did not comment for this article — the methods used to hide a satellite from view have to be inferred from patents issued, expert opinions and the observations of a worldwide network of satellite tracking hobbyists.
In the U.S., the primary means to achieve stealth for aircraft have included using faceted surfaces (F-117A), compound curves (B-1) and planform alignment (F-22), or symmetry of components.
For satellites, the proposed methods have been similar but include additional options, such as dispensing decoys. Although the Defense Department is said to have experimented with stealth satellite designs in the 1970s, the first stealth satellite openly discussed in the media was deployed by the space shuttle Atlantis as part of STS-36 in February 1990. That information came largely from a 2001 book by Jeffrey T. Richelson called “The Wizards of Langley: Inside the CIA’s Directorate of Science and Technology.”
Known as Misty 1 (officially known as AFP-731 or USA 53), the satellite is thought to have been a digital imaging reconnaissance satellite weighing about 37,000 pounds and using the analog of faceted surfaces as its cloaking mechanism. That means an incoming radar beam would have been deflected back in a different direction, similar to a billiard ball’s path when grazing the bumper. The same would have been true of incoming light, either directly from the sun or reflected from the Earth, masking the satellite to optical tracking systems on the ground.
A patent application by workers at Teledyne Industries at about the same time detailed how such a design could work, at least in theory. The cloaking mechanism was a large inflatable cone coated with “radiation reflective material” deployed on a rotating arm on the body of the main satellite. The device could be moved into position to cloak the satellite when needed, then moved out of the way to allow the instruments to see targets on the ground. “The purpose of the invention is to suppress the laser, radar, visible and infrared signatures of satellites to make it difficult or impossible for hostile enemy forces to damage or destroy satellites in orbit,” the applicants wrote.
Another patent in Thomson’s sourcebook, filed in 1971 by TRW, uses anti-radar screens that project out from the main satellite body and its appendages to either totally deny the detection of the satellite by ground-based radars or change its appearance so that the radar cannot distinguish it from nearby decoys.
Declassified memos from the 1960s in Thomson’s sourcebook detail how the U.S. military was considering cross-section reduction techniques, decoys, shielding and other countermeasures, such as hiding among existing satellites. The CIA’s key reconnaissance satellite at the time was code-named Corona. Operated between 1959 and 1972, the space vehicles carried high-resolution cameras and would drop film canisters for midair recovery by Air Force aircraft.
Concerns about satellite survivability increased in the 1980s because of fear of Russian anti-satellite capabilities. The mind-set continued despite the fall of the Berlin Wall in 1989 with the development of Misty 1 and Misty 2, also known as USA 144, a follow-up satellite launched by a Titan IVB booster out of Vandenberg Air Force Base, Calif., in 1997. Both highly classified missions were unveiled to some extent by the amateur satellite tracking community.
Ted Molczan, a Canadian technologist by education and top satellite tracker by hobby, organized a worldwide team in 1990 to track the mysterious payload deployed by the shuttle, and sightings were made. About a week after deployment, however, reports from Russia indicated that five or six objects were being tracked. The assumption was that the satellite had exploded or been deliberately destroyed by the U.S.
Misty 1 appeared to be a closed book until November 1990, when hobbyists in Scotland and France observed an unknown satellite in a similar inclination as Misty 1 but at a much higher altitude. Molczan’s computations showed that there was a good chance the mystery vehicle was Misty 1, meaning the orbital debris the Russians had tracked may have been decoys or debris purposefully generated to hide the intentions of the true satellite.
About a week after news articles announced what the hobbyists had seen, Misty 1 disappeared again, Molczan said.
As with Misty 1, shortly after Misty 2’s launch, nine pieces of debris were catalogued by the Air Force at or above the satellite’s initial orbit, Molczan said. Hobbyists tracked various objects, some for several years, but doubted that the primary satellite was among them. “No one has seen what might be the Misty 2 payload,” Molczan said.
Aside from keeping hobbyists guessing, the need for stealth satellites remains the topic of much debate. Democratic lawmakers in the U.S. Senate’s Select Committee on Intelligence have denounced the multibillion-dollar classified intelligence acquisition program widely thought to be the follow-on to the Misty series and have voted several years running to cut its funds. In each case, Congress has kept the program going through the appropriations process.
Critics argue that enough satellites are already orbiting, stealthy or not, that potential adversaries have moved critical defense-related projects underground.
Thomson is of the opinion that stealth, as one ingredient in a reconnaissance system’s survivability, may be overdone.
“Stealth, properly used, might be
one technique to increase survivability,” he wrote in an e-mail. “Stealth
for survivability enhancement is different from stealth to defeat adversarial
denial and deception (D&D), which I think is mostly a waste of time
these days. Alas, counter-D&D seems to be what the intelligence community
is fixated on.”
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