Experiment to reduce space junk
July 26, 2022 - The ESTCube-2 ultra-small spacecraft, built at the University of Tartu in Estonia, will test a “plasma brake” that can remove a satellite from Low Earth Orbit (LEO) at the end of its mission.
If the mission is successful, the technology will help combat an increasingly pressing problem of space debris. More than 36,500 pieces of orbital debris, or “space junk” size 10cm or above, are tracked by the European Space Agency’s Space Debris Office in Darmstadt, Germany.
The idea behind the plasma brake, conceived by Pekka Janhunen at the Finnish Meteorological Institute, uses a phenomenon known as the Coulomb drag effect.
The effect is an electrostatic exchange of momentum between the ion flow in the upper atmosphere -- the ionosphere stretching to the edge of space -- and the satellite’s 300-metre-long tether, negatively charged with 1,000 volts.
As ESTCube-2 hurtles at 7.6km per second through the ionosphere, the tether reacts with electrically charged ions -- a plasma of atoms and molecules missing electrons and free electrons, created by solar X-rays and ultraviolet radiation -- resulting in a frictional force between the cable and the plasma. This Coulomb drag slowly brakes the satellite’s orbital speed, consequently lowering the orbital altitude.
ESTCube-2 will launch later this year from Kourou, French Guiana, aboard a European Space Agency’s Vega-C launch vehicle.