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canopic jug [soylentnews.org] writes:

In recent years, the odds of orbital collisions has doubled due to all the debris, large particles, and just plain scrap flying around in orbit. These are fragments left from launches as well as from collisions between other objects already in orbit. The Economist is reporting on several methods for de-oribiting space junk are being tested [economist.com], with the goal to get a handle on the problem [spacelegalissues.com] while there is still time to do so. So far, nets, harpoons, and magnets are among the options which have been considered.

In the first test, the servicer will use springs to push the pod out and then, once it is ten metres away, will approach it again, lock onto the docking plate using an arm fitted with a magnetic head, retract the arm and pull it back to the servicer. For the second test, it will push the pod at least 100 metres away before its starts approaching it. A reaction wheel and a set of magnetic torque-generators will then put the pod into a tumble involving all three axes of motion, at a speed of half a degree a second.

This is, as it were, an important twist—for chunks of orbiting debris typically spin in this fashion. A real deorbiting mission will therefore have to deal with such spinning objects. Markings on the pod will help the servicer work out its prey’s motion. Using eight thrusters, it will manoeuvre itself until those markings appear, to its sensors, to be stationary. This will mean its motion exactly matches that of the tumbling pod, and that the magnetic head can therefore be extended to do its job.

For the third capture test, the servicer will first use its thrusters to back off several kilometres from the pod, putting the pod beyond sensor range. Then it will search for it, as would need to be the case if it were hunting for a real derelict spacecraft.

For all the technological prowess these tests will require, however, real derelicts pose a greater challenge than dummy ones. For one thing, unlike Astroscale’s pod, few spacecraft have been designed to expedite their own removal. Also, those objects which most need removing are dangerously heavy. A spacecraft that miscalculates while attempting to capture such a piece of tumbling debris could be smashed to smithereens, thus contributing to the problem it was supposed to be solving.

It is apparently enough to remove the larger objects to achieve significant gains in safety.

Previously:
(2019) Technology to Easily Deorbit Satellites in Development [soylentnews.org]
(2019) Space Harpoon Pitched and Snags Target [soylentnews.org]
(2017) A Satellite May be Falling Apart in Geostationary Orbit [soylentnews.org]

Original Submission