Comment & Analysis
Space debris is becoming such a problem that it could soon be difficult to navigate safe corridors into Low Earth Orbit. Chartered mechanical engineer Lucy Rogers discusses ways of dealing with a man-made problem that is becoming a real threat to space exploration
Engineers are great at getting stuff in to space, but tidying up afterwards has not been a priority - as no-one has been willing to pay for it.
More than 22,000 man-made objects that are in orbit are tracked - but only about 1,000 are operationally spacecraft. The rest no longer serve any useful purpose. The tracked items are larger than a melon. There are over 500,000 pieces larger than a cherry that are not tracked - and millions smaller than that.
We need engineers to use their ingenuity to help solve this problem of space pollution. It is an international problem that requires an international effort. Most space agencies are doing some work to mitigate space debris generation, but no-one is taking responsibility for removing it. We need to improve the tracking and prediction of debris trajectories and to develop tools and techniques to mitigate further debris generation, including collision avoidance and the removal of debris from useful orbits.
Dead satellites and rocket bodies orbit the Earth at around 17,000 mph. When two objects collide in space, thousands of fragments are produced. These themselves become potential hazards. If we do not do something to start removing debris soon, within the next five to ten years, collisions and explosions will make Low Earth Orbit a dangerous place to be and, not long after, we will be without safe corridors to space. This is a threat to many services here on Earth that use space systems, from air traffic control to search and rescue, financial transactions to automated farming equipment.
But it’s not just in space that debris causes problems. About one piece of debris enters the Earth’s atmosphere every day. The smaller bits burn up harmlessly. However, larger items have the potential to reach the Earth, and, travelling at over 200 mph, could cause significant damage if they hit a populated area.
NASA is predicting that the 6,000 kg Upper Atmosphere Research Satellite (UARS) will fall to Earth on 23 September, give or take a day - it depends on, amongst other things, solar activity and atmospheric conditions.
It expects the satellite to break up into smaller pieces, 26 of which, totalling 532 kg, may reach the Earth. The location of where the pieces will land depends on when it enters the atmosphere and begins to break up. This won’t be accurately known until it starts to happen. Hopefully the military’s early warning systems will be able to tell the difference between debris and an incoming missile.
UARS is not the only large piece of debris expected to land on the Earth this year. In late October or early November, the German ROentgen SATellite (ROSAT) X-ray observatory is predicted to re-enter the atmosphere and up to 1,600 kg might reach the surface of the Earth.
However, the rate at which debris re-enters the Earth’s atmosphere is not sufficient to remove the problem. Even if we launched nothing else, orbital collisions will cause space debris to grow catastrophically.
- To find out more about this issue visit www.spacedebrisresearch.com run by Lucy Rogers & Franz Gayl.
- Lucy Rogers has a PhD in fluid dynamics. She is passionate about space and astronomy and is a Fellow of the Royal Astronomical Society and Fellow of the British Interplanetary Society. Visit www.lucyrogers.com for more information.