Orbiting junk is nearing a tipping point, National Academies warn

NASA needs a strategic plan to coordinate how it will deal with the growing hazard of space junk —the flotsam of abandoned spacecraft, spent rocket parts, and other debris—that orbits Earth alongside satellites in use and the International Space Station, according to the report Limiting Future Collision Risk to Spacecraft: An Assessment of NASA’s Meteoroid and Orbital Debris Programs , released early this month by the National Research Council.

The plan should consider how the US will clean up the debris and how it can improve its capacity to track objects and avoid collisions. The amount of debris, which has skyrocketed in recent years, may have reached a ‘tipping point,’ where collisions between two or more pieces of junk set off a train of similar collisions with other pieces, warned the NRC report.

The destruction of a disused satellite in China’s 2007 anti-satellite warfare test, combined with an accidental 2009 collision between an Iridium-33 spacecraft and a Russian Cosmos satellite, doubled the number of orbiting objects that are large enough to be tracked by NASA, the report said. Those 22 000 items range from paint flecks to derelict satellites and the remnants of anomalous events such as failed launches. It is estimated that there are tens of millions of particles, however, that are too small to track, according to the report.

The debris poses a threat both to active robotic satellites and to manned flight. The space station is equipped with shielding to protect it from objects that are too small to track, and NASA employs a collision avoidance model to track larger items. The NRC committee that wrote the report, chaired by Donald Kessler, retired head of NASA’s space debris program office, said that numerous NASA offices—most of them staffed by one person—have responsibility for parts of the agency’s orbital debris and meteoroid programs, but their efforts are not coordinated. The strategic plan the NRC called for should prioritize those programs.

The US is responsible for only about 30% of total orbital debris, the report said. Any cleanup program would be complicated by the acute sensitivity with which nations treat their satellite technologies, and by the international acceptance of a principle that prohibits one nation from salvaging or collecting another’s space junk. The committee recommended that NASA consult with the Department of State on the legal and diplomatic dimensions of the problem. The agency also was urged to educate the public about the debris problem, and to initiate an international effort to record, analyze, report, and share data on spacecraft anomalies.

The committee also called for NASA to improve its characterization of the risk posed by high-velocity meteoroids. Committee members noted recent evidence that small hypervelocity meteoroids may cause electrical damage to spacecraft due to the electrostatic charge or electromagnetic pulses that the meteoroids carry. Unlike space junk, meteoroids cannot be tracked nor their courses predicted.

David Kramer