Published in The Hindu on October 4, 2011
A one-inch long piece of debris in space travels at a speed of 7.5 km per second, about 30 times the speed of a jumbo jet. It can easily destroy a satellite in orbit; and a centimetre-sized fragment can seriously damage a satellite. Researchers are currently tracking some 22,000 junk objects — from small bits of debris to large satellites. There are about 500,000 waste fragments between 1 cm and 10 cm in size. The amount of junk accumulating in space has been growing over the last five decades, and is estimated to triple in the next two decades. Little wonder that a recent report by the U.S. National Research Council warns that the amount of debris in space has already reached a “tipping point.” The increase in debris can come in two ways — addition of new material from broken satellites and spent rocket stages, and newer and smaller objects created by the collision of two waste materials. For instance, in 2009, the collision of two satellites over Siberia — a defunct Russian military satellite (Cosmos 2251) and a functioning U.S. Iridium satellite — created nearly 1,700 waste items. But even more waste was created by the testing of an anti-satellite weapon by China in January 2007 when an obsolete Chinese weather satellite was struck by the weapon. According to Nature, nearly 40,000 particles between 1 cm and 10 cm, and around 800 pieces larger than 10 cm, were created by this collision. According to the report, these two incidents “more than doubled the amount of catalogued debris fragments.”
Several challenges are cropping up as clean-up strategies are being contemplated. Aside from the difficulty and prohibitively expensive nature of the task, removing the waste is dogged by legal problems, a legacy of the Cold War. Under international law, no nation can salvage or collect other nations’ space objects, and this applies to debris orbiting in space! It was time that countries urgently revisited this absurd legal position. The space environment is becoming increasingly hazardous to spacecraft and astronauts. Very recently, the crew of the International Space Station had to take shelter inside the Soyuz spacecraft as a junk item narrowly missed hitting the station. A similar incident had occurred in 2009. Unlike the space station that has special shields for protecting it, the satellites are highly vulnerale to debris strikes. Providing better protection and indulging in debris avoidance manoeuvres are currently the only ways of avoiding damage from impact. But there is yet another problem: these measures are increasing the cost of spacecraft design and operation.