Does anyone control where satellites are launched into space? © Getty Images

Earth satellites may soon need their own traffic control system to stop collisions

Astrophysicist Dr Alastair Gunn explains why changes may be needed to stop satellites colliding in space.

Ever wondered if anyone controls where satellites are launched into space? The answer to this: yes!! Since 1976, the regulatory body for objects sent into space is the United Nations. Responsibility for the maintenance of a register of objects – and that any planned launches are sufficiently separated – lies with the United Nations Office for Outer Space Affairs.

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To date, over 86 per cent of all satellites, probes, landers and crewed spacecraft launched into Earth orbit or beyond have been registered with the UN. Those that haven’t generally predate 1976.

The latest numbers show that there are about 6,250 satellites in Earth orbit, of which about 3,900 are still operating. But Earth’s space environment is populated with a further 28,210 pieces of ‘space junk’ and up to 129 million smaller fragments that can’t be tracked. Such material is monitored optically or with radar by various agencies, often as members of the Inter-Agency Space Debris Coordination Committee.

Even so, satellite operators are finding it harder to avoid the potential for catastrophic collisions. In 2009, satellites Iridium 33 and Kosmos 2251 collided above Siberia, while the latest near-miss happened on 9 April 2021 when a US meteorological satellite passed within an estimated 21m of part of a Soviet rocket launched in 1971.

Furthermore, some experts warn that a ‘critical mass’ of space junk may be only a few decades away. This is where one major collision results in an uncontrollable chain reaction.

Although it may be possible to gather or destroy space debris, it seems likely that some form of ‘space traffic control’ may soon be required – and that future satellites will include autonomous collision avoidance systems.

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Asked by: Ian Holden

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