China test boosted space risk up to 40 pct: U.S. govt

By Jim Wolf

WASHINGTON (Reuters) - A Chinese anti-satellite test in January increased the risk that a spacecraft could collide with debris by up to 40 percent in some orbits, the U.S. Air Force Space Command said on Wednesday.

Before China's test, the Space Command said, there had been a one in 1,000 chance of a satellite in low-earth orbit -- or below 2,000 km -- being struck by a piece of debris 1 cm or larger over a five-year period.

"After the successful China ASAT test, the probability of a low-earth orbit satellite being hit increased 10 to 40 percent," the command said in a written reply to queries from Reuters.

Thus, the risk of a crash with a marble-sized piece of debris or larger rose to a range of 1.1-1.4 in 1,000, depending on the orbit, according to the command, headquartered at Peterson Air Force Base, Colorado.

China used an interceptor aboard a DF-21 missile on January 11 to shatter an obsolete weather satellite in polar orbit, fueling U.S. military concerns about the vulnerability of its eyes and ears in space.

"That successful capability now puts the majority of our low-Earth orbit satellites at some risk, including the ones that are extremely, extremely important to us in our national security," Air Force Chief of Staff Gen. Michael Moseley told a space-industry conference this month.

The biggest U.S. satellite builders are Lockheed Martin Corp., Boeing Co. and Northrop Grumman Corp., which said April 12 that it had teamed with Israel Aerospace Industries Ltd. to pitch small surveillance satellites to the U.S. government in a deal spurred by China's test.

More than 1,600 bits of junk spawned by the test will remain in orbit for decades, increasing by more than 10 percent the total tracked by the Air Force's Space Surveillance Network since the launch of the Soviet Sputnick 50 years ago.

About 700 active spacecraft are in orbits affected by the debris field from the Chinese test, according to the Space Command; about 40 countries have assets on orbit.

David Wright, a physicist and an expert on space debris at the Cambridge, Massachusetts-based Union of Concerned Scientists, said his calculations roughly agreed with the Space Command's.

"We are fortunate that even after the Chinese test, the probability that an individual satellite in orbit will be hit by debris that will destroy it is still relatively small," he said in an e-mail interview.

But the breakup of a single U.S. spy satellite -- with a mass more than 10 times that of the one in the Chinese test and a likely target of an anti-satellite weapon -- could double the amount of marble-sized and larger junk in low-earth orbit.

"Multiple breakups of this kind could significantly threaten our ability to use parts of space for long into the future," he added.