Space junk: A computer-generated artist's impression released by the European Space Agency (ESA) depicts an approximation of all the satellites and other debris in orbit around the Earth. Since the start of the space age the ESA estimates that 6,000 satellites have been launched, 800 of which are still operational.
Credit: ESA
The debris from the defunct 900-kilogram Russian satellite launched in 1993, and its 560-kilogram U.S. counterpart could be significant.
"We are looking at around more than 500 pieces of debris," said Navy Lieutenant Charlie Drey, a spokesman with U.S. Strategic Command (STRATCOM), whose Joint Space Operations Centre tracks and catalogues over 18,000 man-made objects orbiting the Earth.
"Very low-probability event"
"Anytime you have something like this happen, there is a concern about other objects that are in orbit. Now that you have all this debris there, it does pose a risk to satellites," he said.
Analysts are plotting the coordinates of each of the debris pieces, which will later be posted on the website www.space-track.org.
In a statement, Iridium called the crash an "extremely unusual, very low-probability event," adding it has 66 communication satellites in orbit and rejecting any fault for the accident.
NASA spokesman William Jeffs said there was no danger to the scheduled launch of the space shuttle Discovery to the ISS next week.
High velocity
Before the latest incident, there were over 300,000 orbital objects measuring between one and 10 centimetres in diameter and "billions" of smaller pieces, according to a 2008 report by the Space Security Index, an international monitoring group.
Travelling at speeds that can reach many thousands of kilometres per hour, the tiniest debris orbiting can damage or destroy a spacecraft.
In June 1983, the windscreen of the U.S. space shuttle Challenger had to be replaced after it was chipped by a fleck of paint measuring 0.3 mm.
Some 6,000 satellites have been sent into space since the Soviet Union launched the first man-made orbiter, Sputnik 1, in 1957. About 800 satellites remain in operation, according to STRATCOM. NASA's World Book says there are about 3,000 "useful" satellites, without providing details.
