When Sputnik 1 was launched into orbit in 1957, it soared up into a pristine environment. Now, after more than half a century of rockets, space stations, and artificial satellites, that situation has changed, with scientists claiming that it is time to clean up the heavens. According to representatives from the 6th European Conference on Space Debris, there may be more than 30,000 man-made objects circling the Earth that are larger than 10cm in size, and many thousands of others that are too small to detect.
Some of this space flotsam is quite large, such as entire satellites and rocket bodies, but most of the debris is an assortment of fragments created by high-speed extra-terrestrial collisions. Scientists predict that unless at least five to ten large objects can be removed every year, Earth’s near-space environment will become unstable, leading to what is known as the Kessler Syndrome.
Named after American astrophysicist Don Kessler, the Syndrome claims that collisions between space objects generate a cloud of smaller debris, which in turn increases the likelihood of further collisions. Eventually, this becomes a self-generating chain-reaction, creating a hazardous orbital environment and rendering further space operations difficult or even impossible. Kessler and other leading astrophysicists are alarmed at the number of large objects still in orbit, and see their immediate removal as imperative if the so-called “cascade process” is to be avoided.
The costs of removing the junk will be high, but so too is the potential cost of leaving it up there. Heiner Klinkrad of the European Space Agency’s debris office claims that “Whatever we are going to do, whatever we have to do, is an expensive solution.” He sees the situation as one in which the expense of removal needs to be balanced against the enormous value of space infrastructure which needs protecting.
It is estimated that there is currently in excess of $1.3 billion worth of crucial equipment which is at risk, including communication satellites, military surveillance equipment, and the International Space Station. As low-earth-orbit (LEO) technology continues to be seen by governments and commercial enterprises as an important way of monitoring the planet and providing highly effective communications services, that value is likely to increase in the near future.
The Space Debris Conference has recommended that future LEO equipment will need to have a 25 year limit on functionality, after which it should naturally fall out of the sky, but it also sees that the space clean-up is a more pressing matter. Ideas presented at the conference for targeting and removing the debris included the use of harpoons, nets and lasers.
The German Space Agency (DLR) is also developing systems to capture stray objects in space with robot-arm technology. At present, however, developing a viable technique for getting rid of the debris is only half of the problem, as current international law forbids anyone but the launching nation or agency from touching the orbiting objects.
What seems clear is that this is a problem that will only get worse if not tackled immediately. If future generations wish to “boldly go where no-one has gone before,” it seems essential to kick-start a clean-up of a space environment where humanity’s presence is all too apparent.