Cleaning up in orbit

A UK based firm intends to combat the menace of huge bits of debris in orbit of the Earth, threatening satellites and space travel. In future, Astrium hopes every satellite that goes up will have a device developed by it and the University of Surrey to pull it down again later on.

The shoebox sized CubeSail contains a large sail within. Once it is time for the satellite to end its life, the sail is deployed in one of two configurations. In low Earth orbit, the sail can be deployed perpendicular to the surface of the Earth. Friction with the exosphere at these altitudes should be sufficient to bring the satellite to below orbital speeds in a reasonable timescale. For higher up pieces, where the exosphere is too thin for this, the sail will be pointed directly away from the Sun and solar radiation pressure will be relied upon to push the satellite down a bit.

There are 5,500 tonnes of dead material up there in sizes ranging from tiny blobs to entire dead satellites and it is increasing at a rate of five percent a year. The United Nations Office for Outer Space Affairs recommends that countries should aim to bring what has gone up back down within twenty-five years of mission end. Unfortunately, none of this quite tackles the stuff that’s already there. We just have to hope that tackling the rise adds enough to the natural depletion to at least stabilise what’s up there.


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