Headline: Editor's Note: This story was updated at 11:27 a.m. ET.
NASA's 2003 budget does not include funding for its Orbital Debris Program Office, which monitors space junk that could damage or destroy satellites and other spacecraft. If funding is not restored by the end of September, the program will cease operations Oct. 1.
But NASA Headquarters is reviewing the program and could restore the budget before the fall deadline, SPACE.com has learned.
The program, begun in 1979, has helped reveal the existence of more than 100,000 bits of small, mostly manmade space debris that are not tracked by any other agency. The junk has the potential to damage space shuttles, the International Space Station, and other spacecraft.
This is not the first time managers of the Orbital Debris Program Office have worried about money. Funding this year was cut by 50 percent compared to previous years, said Nicholas Johnson, chief scientist and program manager for Orbital Debris at NASA's Johnson Space Center, where the program is run.
A story Friday by the United Press International first reported that the program's budget would be eliminated by NASA Headquarters, despite recommendations from an advisory panel early this year to restore it.
Johnson said this morning, however, that officials at NASA Headquarters are still reviewing the situation. He is concerned but expressed confidence that something would be worked out. He and his colleagues have lobbied Headquarters to provide the necessary funding.
"If it's not funded, then in fact the program is terminated," Johnson said.
The separate U.S. Space Command, a military agency, catalogues and tracks debris larger than 10 centimeter (4 inches) and would be unaffected by any decision regarding the small-debris program.
The Orbital Debris Program Office uses data collected by radar telescopes and other observatories to detect debris from 10 centimeters (4 inches) down to the size of a pinhead. The researchers do not track the debris over time, but they use statistical models to predict how much will exist at various altitudes.
Space agencies around the world rely on the results to help position spacecraft and keep them safe.
"We're the only people in the world that do this kind of work," Johnson said. He added that the statistical models have a high degree of accuracy because they include data that goes back more than two decades.
Small junk, some of it created by rocket explosions, can rip holes in a spacecraft or disable a satellite by causing electrical shorts that result from clouds of superheated gas, called plasma, that are sometimes generated in an impact.
Even something the size of a paint chip or a sand grain can damage a spacecraft. Johnson said that because large debris is systematically and individually tracked, it is much more likely that damage will be done by untracked debris, the small stuff for which Johnson's team predicts the general whereabouts.
Spacecraft that carry astronauts have beefed-up protection against this small debris. They sometimes alter course to avoid larger objects.
But most satellites, including observatories like the Hubble Space Telescope, are not well protected against anything larger than sand grains, Johnson explained earlier this year. In fact, Hubble has a 3/4-inch hole to prove it.
Johnson and his colleagues have used photographs taken by astronauts during Hubble servicing missions to learn more about what sorts of debris are up there and what happens when something hits a spacecraft. They also examine space shuttles after each flight to glean similar knowledge.
Windowpanes on shuttles frequently must be replaced due to impacts.
NASA estimates there are 4 million pounds of junk orbiting Earth. More than half the impacting debris is manmade, Johnson says. It travels at about 10 kilometers per second (22,370 mph). Small asteroids and meteoroids -- the natural debris -- typically move at twice that speed.
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