Space: the world's new garbage dump

In “Gravity”, an astronaut duo played by George Clooney and Sandra Bullock are left adrift in space after their shuttle is destroyed. The culprit is Hollywood’s newest villain: space debris. Unfortunately for present day astronauts, this is not just Hollywood’s febrile imagination at work. As innocuous as it may sound, space debris is extremely hazardous and could even be lethal. In fact, the National Aeronautical Space Administration (Nasa) has initiated an entire programme, the Orbital Debris Programme Office, dedicated to studying and monitoring this manmade phenomenon. The international community, including the European Union and United Nations, has meanwhile been pursuing resolutions to mitigate and reduce space debris.

Nasa classifies space debris into two groups: natural (meteoroid) and artificial (manmade) particles. Most artificial debris is found in orbit around the Earth; hence it is called orbital debris. Nasa further defines orbital debris as “any manmade object in orbit about the Earth which no longer serves a useful function”. This includes non-functional spacecraft, abandoned launch vehicle stages, mission-related debris and fragmentation debris.

Presently, both the Department of Defence (DOD) and Nasa track orbital debris as miniscule as 5 centimetres in size. Per Nasa estimates, there are more than 500,000 pieces of debris larger than a marble and up to 20,000 pieces larger than a softball floating around the Earth’s atmosphere. This debris is incredibly dangerous as it whizzes in orbit at speeds in excess of 17,500 mph. At these velocities, even the smallest piece could incapacitate a satellite or spacecraft.

As early as the 1970s, scientists working on both the US and Russian space programmes were becoming increasingly alarmed by the exponential growth of orbital debris. Nasa’s Donald J Kessler studied the potential dangers of colliding space debris. In what was later dubbed the “Kessler Syndrome”, he postulated that the volume of space debris increases with the number of launches, especially in the low Earth orbit (LEO). Over time, the density of debris will increase, causing collusions that produce even more debris. Often, this debris will fall harmlessly to Earth. But Kessler believed the remainder could ultimately form a “debris belt” around the Earth that would inhibit space travel. A 2008 report by the Council on Foreign Relations concluded that orbital debris is like radioactive fallout after a nuclear detonation because it can linger for many years.

Currently, the LEO has the highest concentration and rate of growth of debris than any other orbit. Debris concentrations more than doubled in the LEO between 2004 and 2009. There are myriad reasons why the LEO is a preferred orbit but one of the most important is that it is good for Earth observation missions (weather, intelligence and communications satellites). Most satellites operate on Sun-synchronous orbits in this region at altitudes of between 600 and 900 kilometres. As a result, this is also the orbit where most collisions occur. The UN’s Office of Outer Space Affairs Committee on the “Peaceful Uses of Outer Space” draft report in 2010 notes that the first collision in this region occurred on February10, 2009 between an Iridium-33 (US) and Cosmos-2251 (Russian) satellite. This event alone produced more than 2,200 traceable items.

The emergence of a new player in space complicates the issue. With China’s first successful satellite launch in 1970, the advent of manned spaceflight in 2003 with astronaut Lang Liwei, a proposed Moon rover launch by the end of this year and the planned Tiangong-2 (Heavenly Palace-2) space lab to debut around 2015, the volume of orbital debris is expanding rapidly. This amplification of the “Kessler Syndrome” threatens not only the international community’s stellar assets but also Chinese ones as well, including the safety of their astronauts, commonly referred to as taikonauts.

The European Space Agency (ESA) has been cataloguing orbital debris contribution by country for decades. Although Russia and US have to date done most to clutter the cosmos, Chinese orbital debris has risen precipitously since the early 2000s. On January 11, 2007, China single-handedly increased large orbital debris (greater than 10cm in diameter) by 10 per cent when it conducted an anti-satellite test (A-SAT) that created more than 2,500 pieces of debris. In this test, China launched a kinetic kill interceptor/vehicle from western China that collided with its orbiting FengYun-1C satellite. Despite international condemnation of the test, Geoffrey Forden, an MIT researcher, thinks that it is highly unlikely that the Chinese will fully abandon future A-SAT testing. Nasa concluded that it would take more than 100 years for the fallout from the collision to reenter the atmosphere. In the meantime, stellar objects remain at risk.

For its part, China has acknowledged space debris. It has joined numerous international organisations that seek to mitigate or reduce orbital debris, such as the Inter-Agency Space Debris Coordination Committee (IADC). The current English version of the China National Space Agency’s webpage does have a tab for space debris. When clicked, however, it directs only to a 2007 announcement that the Chinese-hosted 25th meeting of the IADC had to be postponed until further notice. Interestingly, the Chinese version does not have a space debris tab or notice posted, but it does have a link to statistics on American orbital debris. Yet at its present trajectory, it would seem that China is on track to becoming the leading space polluter.

Despite Congressional restrictions on some bilateral space arrangements between the US and China, there is ample opportunity for more constructive measures with the international community. A good starting point would be to incentivise countries with space programmes to reduce debris through better mission planning or spacecraft construction. Both measures would contribute significantly to what the US State Department calls enhanced space stability. A second, far more optimistic goal would be to ban ASAT weapons and testing. Happily, many of these proposals are underway.

With so much orbital debris, “Gravity’s” storyline is far from preposterous. If the international community cannot collaborate to reduce or mitigate orbital debris, there very well could be a non-fictional sequel to “Gravity”. Unfortunately, this time Chinese “taikonauts” could be in the leading roles.

 

Wilson VornDick is a lieutenant commander in the US Navy, where he is assigned to the Pentagon. This piece reflects the author’s opinions only.