ST. LOUIS — A successful Chinese missile test last year that destroyed one of China’s own aging satellites has substantially added to space debris around Earth, increasing the danger that a chain reaction of colliding space junk could threaten parts of the world’s satellite network, scientists said Tuesday.
The threat is that debris would begin slamming into other debris, creating a cascading effect called super-criticality, according to scientists addressing the American Physical Society conference here this week.
“Debris in space is already a problem,” said David Wright, a senior scientist with the Union of Concerned Scientists in Cambridge, Mass. “But it’s potentially a very big problem.”
Geoffrey Forden, a Massachusetts Institute of Technology physicist and an expert on China’s space program, said the danger from space debris is more of a worry than the threat that some country could intentionally cripple U.S. space assets with anti-satellite weapons.
Forden argued that the United States’ redundancy in space satellite systems makes it almost “invulnerable” to that kind of attack. And it would be relatively easy to spot the Chinese readying a launch.
On the other hand, “we are in danger of a runaway escalation of space debris.”
According to Wright, the Chinese shoot- down on Jan. 11, 2007, added more than 2 million pieces of debris in low-Earth orbit, which is where most satellites are.
Because there is already so much debris — more than 150 million pieces, most of them less than 2 inches across — even if nothing more is added, the amount will still increase by a factor of three in the next 200 years because of fragmentation from collisions and other reasons.
That could be a low figure if more anti-satellite tests take place. Destruction of one 10-ton satellite can contribute up to 15 million pieces of junk, thousands of them more than a foot across.
Forden said the threat of super-criticality is a warning that it’s time to treat space as a natural resource that must be protected.
“We’re fortunate we haven’t really screwed things up yet,” Wright said. “But the Chinese test brought home how quickly this could get out of hand.”
