Tuesday, April 24, 2007

China’s deliberate destruction of one of its own satellites in a January test of an anti-satellite (ASAT) weapon has led to much hand-wringing about the creation of space debris, reinvigorating the opponents of weapons in space. Orbiting debris is dangerous, but the danger has been greatly exaggerated and is no reason for new unenforceable arms control agreements.

When the space age began 50 years ago there were no man-made objects in space. Since then, Space Command has tracked more than 25,000 objects of baseball size or larger. More than 10,000 have fallen into the atmosphere and disintegrated or landed, but in 50 years not one person anywhere on Earth has been killed or injured by falling debris.

Space debris is only slightly more likely to strike one of the 850 active spacecraft. Most are in low Earth orbit below about 800 miles. These operational spacecraft are only 6 percent of the objects tracked. The rest is space junk that includes inactive satellites, spent rockets, debris from exploding rockets and just plain trash. Space Command monitors debris to identify threats and alerts operators of satellites to move out of the way if they appear to be in danger.

Some 80 percent of debris orbits between 500 and 600 miles altitude. The Chinese test, at 527 miles, created more debris right where traffic is heaviest. Air Force Space Command is tracking more than 1,000 pieces of debris from the Chinese test, plus 14,000 that were there before. So far, none has hit an active spacecraft. In fact, over the last 50 years there have been only three documented debris impacts with operational spacecraft, and none have been destroyed.

A Space Command Web site describing the Space Surveillance Network that tracks debris notes there is only a small amount in the low orbits of the space shuttle and space station, and gives a worst-case estimate of 1 chance in 10,000 years of a piece of debris of baseball size or larger hitting either one.

Even in the debris-heavy area around 500 miles altitude, Space Command says normally there are only three or four objects orbiting in an area equivalent to the airspace over the continental United States up to an altitude of 30,000 feet. Thus, it states, the likelihood of a collision is very small.

Now there are reports U.S. intelligence agencies knew about and monitored Chinese preparations for the ASAT test, but senior administration officials decided to say nothing to deter Beijing in orderto protect intelligence methods. That shows that despite the anguish about space debris the creation of more was not considered a serious danger.

Most debris eventually migrates down and burns up in the atmosphere. The main efforts are to avoid existing debris, design spacecraft and rockets that will not explode in space, limit the release of debris on orbit, and at the end of their mission de-orbit satellites or move them to parking orbits where there is little traffic.

The Inter-Agency Space Debris Coordination Committee (IADC) is an international governmental group that promotes good conduct in space. Most space-faring nations are members, including the United States, Russia, China and the European Space Agency, which together have created some 95 percent of space junk. The IADC was supposed to meet in Beijing in late April, but after creating a new debris field, China postponed the meeting until November.

Now an earlier meeting at a new location is under consideration. It will be interesting to see if China explains its anti-satellite test. By conducting the test without advance notice to anyone, Beijing ignored the concerns of governments and commercial satellite operators alike, and violated a cardinal rule of the IADC by creating a lot of long-lived debris at a relatively high altitude.

Though the danger is not as great as many believe, China’s action has led to renewed calls for a ban on tests in space that might cause debris. That would be a mistake. Banning weapons or tests in space could adversely affect our ability to protect our armed forces on land and sea from satellite reconnaissance and targeting.

ASAT technologies that do not cause debris are under development and need to be tested in space. China’s aggressiveness in space and Russia’s military resurgence may require us to develop new defensive weapons. We do not need another treaty that we honor while our adversaries do not.

The IADC has adopted standard practices to mitigate orbital debris. China deliberately violated those standards. At the next IADC meeting the other space-faring nations should insist that China explain its actions and press Beijing to act more responsibly. They also should review the guidelines to see if they can be improved. Space debris is a problem, but it is manageable and should not be used to limit our freedom of action in space.

James Hackett is a contributing writer to The Washington Times and is based in Carlsbad, Calif.

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