Collision reminder of space’s junkyard

On Jan. 17, the engine from a Thor rocket launched 31 years ago was soaring southward, 550 miles over the African continent.

At the same time, a fragment of a Chinese rocket that blew up five years ago was high over the Pacific Ocean, also headed south.

Incredibly, the two chunks of metal flew into the same spot over Antarctica at the same instant.

The high-speed collision, reported last month by NASA’s Orbital Debris Quarterly News, created even more orbiting space junk. It also drew renewed attention to the litter that surrounds our planet – and efforts to keep the neighborhood from becoming even more cluttered and dangerous.

“It’s sort of a classic environmental problem, not unlike air pollution or water pollution,” said Nicholas Johnson, chief scientist and program manager for NASA’s orbital debris program. “If you wait until you start seeing negative consequences, then the environment is pretty far gone already, and cleaning it up can be very, very difficult.”

When the shuttle Discovery is finally launched, most likely in July, it will join more than 13,000 pieces of orbiting hardware that the U.S. military tracks 24 hours a day.

Among them are hundreds of working satellites – and thousands of dead ones – along with spent rockets and other odd scraps set loose by decades of breakups, explosions and collisions.

The junk pile includes about a ton of radioactive fuel from defunct reactors launched into orbit before the practice ended in 1988, according to a recent report to the Fourth European Conference on Space Debris.

Much of the material is concentrated in “low-Earth orbit,” which extends to about 1,200 miles and is home to the International Space Station and hundreds of communications, environmental, scientific and spy satellites.

A thousand more satellites – about half of them working – cluster in a slender ring, like a bicycle tire, about 22,000 miles above the equator. They orbit once a day, hanging above the same spot on the ground as the Earth spins. These “geosynchronous” orbits are ideal for communications satellites, which must stay in view of fixed dish antennas on the ground.

Everything larger than a softball is tracked 24 hours a day by the 1st Space Control Squadron. It’s a part of the U.S. Air Force Space Command, tucked deep into the Cheyenne Mountain in Colorado Springs, Colo., along with the nation’s aerospace and ballistic missile warning centers.