Trackers of Orbiting Junk Sound Warning

There are 19,000 pieces of debris larger than a softball orbiting the Earth. They travel at about 17,000 miles per hour, fast enough for a relatively small piece of junk to destroy a satellite or even the space shuttle.
There are 300,000 pieces of debris the size of a marble or larger, according to Paul Graziani, chief executive of Analytical Graphics, Exton, Pa., a maker of software for the space and defense industries.
There are 3,000 "payloads" in space - sensors, transponders and other equipment used by the communications industry, the military, scientists and others, Graziani said. And 1,400 times each week, a payload comes within three miles of a piece of debris that could damage or kill it.
Graziani knows. His company produces the software that the U.S. government uses to track space debris.
With so much junk and so many near misses, there have been surprisingly few disastrous collisions - about eight, according to Andrew Palowitch, director of the U.S. Air Force and National Reconnaissance Office Space Protection Program.
In 1996, a French satellite was hit and damaged by debris from a French rocket that had exploded a decade earlier.
In 2007, a spacecraft built by China and Brazil suddenly broke apart, likely the result of a collision with space junk.
The most spectacular space crash occurred Feb. 10, when a defunct Russian satellite collided with and destroyed a functioning U.S. Iridium commercial satellite. The collision added 1,131 pieces of trackable debris to the inventory of space junk.
China's 2007 anti-satellite test, which used a missile to destroy an old weather satellite, added 2,500 pieces to the debris problem.
A similar demonstration by the United States in 2008 was conducted at a much lower altitude - about 180 miles compared with China's 500 miles - so the debris re-entered Earth's atmosphere and burned up within about two weeks, Graziani said.
The increase in space debris has greatly increased danger to the space shuttle and astronauts at certain altitudes, Palowitch said.
During the recent mission to repair the Hubble Space Telescope, the U.S. space shuttle Atlantis faced a 1-in-229 chance of suffering a disastrous collision with space junk. The risk was high enough to prompt NASA to prepare a backup shuttle for a rescue mission.
Astronauts working in space on the Hubble faced a 1-in-89 chance of being killed by space debris, Palowitch said.
Over the next five years, 2,200 additional satellites are scheduled to be launched, and there are likely to be at least 10 more major collisions in space, he said.
Palowitch and Graziani explained the problem of space debris to a gathering of congressional staffers and news reporters June 10.
Palowitch's Space Protection Program was created last year to search for solutions to the problem of space debris.
The first step is to prevent it, Palowitch said. Spacefaring nations must agree to limit the number of rocket parts that they leave in space, he said.
Second, there is a need for better tracking and identification of debris and for calculating the likelihood of collisions. The United States has no debris-tracking capabilities in the southern hemisphere.
Third, there is a possibility that some space debris could be cleaned up, Palowitch said.
U.S. government research laboratories are experimenting with the possibility of using ground-based lasers to burn the surfaces of space debris to create more drag as the pieces fly through space, causing them to re-enter the atmosphere sooner and burn up.
"But lasers and space are very touchy," Palowitch said. U.S. adversaries - and some allies - are likely to take a dim view of the United States firing lasers into space. Lasers might also be used as anti-satellite weapons.
Space could be partially cleared if dead satellites could be repositioned, either to re-enter the atmosphere or to be placed in "garbage orbits," where they are out of the way of working spacecraft, Palowitch said.
The United States is spending $3.2 billion this year and $7 billion over the next five years on "space situational awareness" programs to improve the ability to track debris.
"It's a good start," he said, but in the long run, it might not be enough.