Space junk

Science World, Oct 6, 1997

Space may be the final frontier, but it's not free of human pollution. Scientists are concerned that the debris from disintegrating spacecraft is cosine a threat to other spacecraft and satellites.

According to NASA, there are now more than 500 working satellites, 2,000 defunct satellites, 1,400 used rocket boosters, and 1,100 smaller objects floating in orbit. Since the beginning of space exploration in 1957, more than 137 spacecraft have exploded or broken apart while in orbit around Earth. Over time, even working spacecraft lose bolts and screws.

And space junk moves fast--several thousand kilometers per second. At that speed, even the tiniest scrap can cause huge problems. NASA engineers think an electronic circuit board hit the Columbia space shuttle, leaving a 6-millimeter dent in the door of the shuttle's cargo bay. Had the door been open, the speeding projectile could have pierced the shuttle's vulnerable oxygen tanks.

In fact, spacecraft and satellites collide quite often with space junk. So much debris has bounced off the shuttles that NASA has had to replace 63 shuttle windows since 1981. Several thousand near-misses (within 10 km, or six miles) involving junk and satellites happen every day, according to Timothy Payne, a scientist at Falcon Air Force Base in Colorado.

NASA fears the situation will only get worse. Private companies plan to launch hundreds of new satellites for TV, radio, and Internet communication. What do you think? How can we clean up space?