The crew aboard the International Space Station (ISS) have been directed to take evasive action to avoid space debris no less than 14 times, spending precious fuel to nudge the course of their 450-ton home. They have had to pack themselves into their cramped Soyuz lifeboat an additional three times. When China destroyed the Fengyun 1C weather satellite with a ground-launched missile in 2007, the largest cloud of space debris in history was created. Over 3200 trackable objects from Fengyun 1C were cataloged by the US military, with more than 90% of that debris still in orbit — and that’s just a small sample of the debris that is making its way around the Earth clogging up orbital paths and making things unsafe for some very expensive equipment.
The Fengyun favor was returned, unintentionally, in 2009, when the American Iridium 33 communications satellite catastrophically collided with the defunct Russian Cosmos 2251 payload module 490 miles above Siberia. Scientists determined that the debris posed a direct threat to many of their sun-synchronous satellites — those whose orbits ascend or descend over a given Earth latitude at the same mean solar time.
The loss of an occasional satellite is far from a disaster, but if China, for example, were to roll out a space laser capable of de-orbiting satellites, more than a few eyebrows would be raised. The US Air Force and NASA funded a study in the 1990s, called Orion, to determine the feasibility of building such a laser. The “laser broom,” as it came to be called, would target pieces of debris between one and ten centimeters in diameter, and could significantly alter their velocity using a 100-kilowatt infrared laser. A test device was scheduled to fly on a 2003 Space Shuttle mission, however the Columbia disaster led to several postponements. Ultimately, numerous international agreements restricting lasers in orbit limited the laser to a measurement device.
Tracking of space debris has evolved from crude catalogs and databases into sophisticated models run with powerful simulation software. But even the best models need good data, or sensor tracks. A case in point is the calculations made by CelesTrak orbital element software, from Analytical Graphics Inc. (AGI), which indicated that the Iridium and Cosmos satellites would miss by at least 584 meters. AGI’s flagship product, the Satellite Tool Kit, is used worldwide in over 40,000 installations by aerospace, defense, and intelligence professionals.
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