Experiência para reduzir lixo espacial
July 26, 2022 -
A pequeníssima nave ESTCube-2, construída pela Universidade de Tartu
na Estónia, vai testar um “travão de plasma” capaz de remover um satélite em órbita baixa no final da sua missão.
The primary purpose of the satellite’s mission is to test a plasma brake, which will reduce the craft’s orbit and burn it up in the Earth’s atmosphere at the end of its mission.
If the experiment 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 7-8km 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.