Last week, six astronauts living on board the International Space Station (ISS), which orbits some 200 miles above the earth’s surface, received notice that a piece of space debris travelling 29,000 miles per hour would pass dangerously nearby. NASA officials calculated that the probability of the ISS being hit at around one in 360. (One in 10,000 is NASA’s nominal threshold for which it will authorize a “collision avoidance maneuver.”) Normally, the ISS receives ample notice so that it can maneuver out of the pathway of potential space debris. However, with less than fifteen hours’ warning, the astronauts were forced to relocate to Soyuz space capsules for only the second time in the ISS’s thirteen-year history.
While the debris missed the space station by 1,100 feet, orbital space debris is a growing threat to civil, military, and commercial satellites in space. Presently, there are some 22,000 items over ten centimeters across, or roughly the size of a softball, which can be regularly tracked with existing resources and technology. These include the upper stages of launch vehicles, disabled spacecraft, dead batteries, solid rocket motor waste, and refuse from human missions. In addition, there are approximately 300,000 other fragments of space junk measuring between one and ten centimeters, and over 135,000,000 less than one centimeter, which could potentially damage operational spacecraft.
Though it took forty years to produce the first 10,000 pieces of softball-sized space debris, it required less than a decade for the next 12,000. This recent increase was due in part to two worrying incidents, which, according to NASA, combined to increase the number of total space objects by over 60 percent. In January 2007, the Chinese military destroyed a defunct polar-orbiting weather satellite with a mobile ballistic missile, and in February 2009 an active Iridium communication satellite and a defunct Russian satellite, which had been predicted to pass each other 1,900 feet apart, unexpectedly collided.
The ability to detect, track, characterize, and predict objects in space and space-related events is known as space situational awareness (SSA). The U.S. Strategic Command’s Joint Space Operations Center (JSpOC) provides this function for the Pentagon by monitoring space debris (over ten centimeters) with a worldwide network of twenty-nine ground-based radars and optical sensors.
In addition to supporting U.S. military and intelligence agencies, JSpOC provides e-mail notifications to commercial space operators when their satellites are at risk from space debris. JSpOC provides twenty to thirty close-approach notifications per day, which last year resulted in satellite owners maneuvering 126 times to avoid collision with other satellites or debris. According to U.S. officials, the United States even notifies the Chinese government when their satellites are threatened by space debris created by the 2007 anti-satellite test. Despite JSpOC’s best efforts, however, these same officials acknowledge that no country has the resources, technical expertise, or geography to meet the growing demands for SSA.
The space debris problem is a classic global governance dilemma: though eleven states can launch satellites, and over sixty countries or government consortia own or operate the approximately 1,100 active satellites, no one country or group of countries has the sovereign authority or responsibility for regulating space. Under Article II of the 1967 Outer Space Treaty: “Outer space, including the moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty.”
The solution to reducing the amount of new space debris, mitigating the threat it poses to satellites and spacecraft, and eventually removing on-orbit debris from space, will require enhanced international cooperation. Last summer, the Obama administration released its National Space Policy, which featured the objective of preserving the space environment via “the continued development and adoption of international and industry standards and policies to minimize debris,” and “fostering the development of space collision warning measures.” Unfortunately, progress toward constructing international agreed upon rules of the road for the responsible uses of space have been slow going.