By Xinhua,
Beijing : Debris from the U.S. intercept of a spy satellite in February and from China’s anti-satellite test in Janaury 2007 is still orbiting Earth, according to a space debris expert.
T.S. Kelso’s CelesTrak satellite tracking software shows some 15 pieces of the busted up USA 193 spysat are still flying around, although when the successful intercept was reported, estimates were that all pieces would re-enter Earth’s atmosphere within 40 days.
A recent analysis shows the last piece of clutter will decay about 100 days post-intercept, Kelso reported.
To generate accurate whereabouts of Earth orbiting debris, experts use data in the form of what’s known as Two-Line Elements, or TLEs.
“We still don’t have any way to predict when the piece still identified as USA 193 will decay, since we have never received any TLEs for it,” Kelso explained. “It’s almost as if that orbit was still classified, which seems a bit odd. You would think TLEs for all pieces would be released.”
Kelso explained that, with fewer pieces of USA 193 speeding about the Earth, there are only a half dozen or so close approaches a week to other spacecraft. “So it would appear that this threat is diminishing.”
The Chinese anti-satellite (ASAT) test back in January 2007 created so much space litter that there are 3,144 close approaches of leftover debris with other satellites over the next week, according to a recent analysis, Kelso said.
In a debris update, NASA information puts the known leftover flotsam from the USA 193 intercept at 12, as of May 12. Furthermore, a government estimate of the maximum lifetime of orbital debris from the intercept — made prior to the intercept — pegged the last piece of clutter to fall back to Earth this summer, longer than 100 days post-event.