– Operators of satellites in low Earth orbit and agencies that monitor traffic there say the recent destruction of a Chinese weather satellite by a Chinese ground-launched missile is unlikely to pose much risk to other spacecraft in the short term.
But because of the dispersion of the satellite’s pieces following impact, the collision presents a longer-term danger that cannot be discounted.
The missile strike occurred at
10:25 p.m. GMT
5:25 p.m. EST
) Jan. 11 at an altitude of 863 kilometers, where the Chinese FY-1C satellite, launched in 1999 and since retired, had been in sun-synchronous orbit.
Beyond the political or military issues involved, the test represents the first time a satellite has been intentionally destroyed in such a high, and frequently used, orbit, according to
and European officials who track orbital debris.
Several dozen Earth observation and meteorological satellites use that orbit, including
‘s own FY-series craft.
‘s next-generation meteorological satellite, the FY-3A, is scheduled for launch this year.
“This event is very disappointing,” said Heiner Klinkrad, head of the space debris office at the European Space Agency’s Esoc operations center in
. “Destroying a satellite at this altitude, in sun-synchronous orbit, presents a debris problem about as serious as you can get.”
The U.S. Defense Department’s Space Surveillance Network, a series of ground-based radars that track orbital objects and debris as small as 5 centimeters across, had identified 32 pieces from the FY-1C satellite as of Jan. 23.
Experts said it is likely that hundreds, and perhaps thousands, of small and undetected pieces of the satellite also were thrown off by the impact.
data shows that the identified pieces had separated into two clusters. One is dispersed over altitudes low enough that the debris will re-enter the Earth’s atmosphere relatively quickly.
But the second cluster was jettisoned into orbits with apogees as high as 3,500 kilometers, with other pieces at 1,700 kilometers, and a perigee of 863 kilometers, meaning they travel between those two points each time they circle the Earth.
“Some of these pieces can be expected to remain in orbit for more than 100 years,” Klinkrad said.
The U.S. Space Surveillance Network is by far the world’s most sophisticated, and its data is used as a reference by other nations. But even that system is patchy – “like looking through a keyhole as objects speed past,” Klinkrad said.
routinely analyzes the
radar network’s findings but the agency’s orbital debris experts were reserving judgment on the debris impact until further data is in.
“NASA is not yet at liberty to discuss the debris consequences of the breakup,” said Nicholas L. Johnson, NASA’s chief scientist for orbital debris. “However, thorough environmental assessments are and have been under way. We anticipate that information on this event will be released shortly.”
NASA Administrator Michael Griffin, in Paris Jan. 23 to meet with representatives of the nations building the international space station, said NASA’s early analysis is that the station will not be put into danger by the Chinese debris.
“We perform debris analysis all the time in recognition of the possibility of collision-avoidance maneuvers,”
said of space station operations. “That has not changed, and so far we have not seen any need for a collision-avoidance maneuver.”
NASA policy is to maneuver the station if orbital calculations show a greater than 1-in-10,000 chance that a piece of orbital debris might threaten the orbital complex.
T.S. Kelso, technical program manager at the Center for Space Standards and Innovation (CSSI) in
, a research arm of Analytical Graphics Inc., said it is premature to dismiss the long-term risk to satellites and to the international space station from the Chinese debris.
Kelso and CSSI, using data from the U.S. Space Surveillance Network, have plotted the future paths of the Chinese debris and the orbit of the space station and low-orbiting satellites and concluded that owners of any spacecraft should take the necessary precautions.
“I liken it to crossing a street with heavy traffic,” Kelso said. “If you use a tunnel under the street, or a bridge over it, you know you’re OK. But otherwise you better look both ways, and carefully. These issues can be [handled] with a collaborative effort, but if we keep sweeping them under the rug and assuming everything is OK, someone is going to learn the lesson the hard way.”
Kelso said his analysis of the orbit of the Chinese FY-1C satellite before the Jan. 11 missile impact suggests that the Chinese did not maneuver the satellite into a new position to prepare for the anti-satellite test.
Several officials said they were doubly surprised by the Chinese action because
has been an active member of the 11-member Inter-Agency Space Debris Coordination Committee, a group which represents almost all spacefaring nations.
The committee has been the source of debris-mitigation policies that all members have endorsed, even if the rules are nonbinding.
The committee meets once a year. Its next meeting is scheduled for April – in