According to Joel Primack writing in the Bulletin of the Atomic Scientists a really big dust-up in low Earth orbit caused by anti-satellite weapons could render LEO unusable for satellites:
But in reality, space does not clear after an explosion near our planet. The fragments continue circling the Earth, their orbits crossing those of other objects. Paint chips, lost bolts, pieces of exploded rockets—all have already become tiny satellites, traveling at about 27,000 kilometers per hour, 10 times faster than a high-powered rifle bullet. A marble traveling at such speed would hit with the energy of a one-ton safe dropped from a three-story building. Anything it strikes will be destroyed and only increase the debris.
With enough orbiting debris, pieces will begin to hit other pieces, fragmenting them into more pieces, which will in turn hit more pieces, setting off a chain reaction of destruction that will leave a lethal halo around the Earth. To operate a satellite within this cloud of millions of tiny missiles would be impossible: no more Hubble Space Telescopes or International Space Stations. Even communications and GPS satellites in higher orbits would be endangered. Every person who cares about the human future in space should also realize that weaponizing space will jeopardize the possibility of space exploration.
To a scientist whose research has benefited enormously from space observations, these prospects are horrifying. Many of the important astronomical satellites are in low Earth orbit (from the lowest practical orbits—about 300 kilometers—to about 2,000 kilometers above the Earth). The Cosmic Background Explorer, which operated from 1989 to 1994, is at 900 kilometers and the Hubble Space Telescope is at about 600 kilometers.
In addition, most Earth-observing satellites are also in low Earth orbit, both those that study changes in climate and vegetation and those for military surveillance. Low orbits permit the highest-resolution imaging, and are also easiest to reach with existing launch vehicles.
Unfortunately it is probably impossible for treaties to prevent the inevitable development of anti-satellite weapons. US adversaries such as China see US military satellites as high priority targets in any future conflict with the US. The history of arms control treaty cheating (eg the massive Soviet biological weapons program) suggests that only countries that want to obey treaties will do so - especially among the less democratic and less open nations.
What would be interesting to know is whether any low cost techniques could be developed for doing clean-up after massive amounts of small fragments were released into LEO. Could one make, for instance, large very thin sheets unfolded and moved around in orbit (perhaps using solar wind?) to try to get fragments to collide with them? Every collision - even if the collisions punch right thru the thin sheets - is going to rob a fragment of momentum. Rob of them of enough momentum and they will fall out of orbit.
|Share |||Randall Parker, 2002 October 05 03:57 PM Airplanes and Spacecraft|