Space DebrisThe US Naval Research Laboratory (NRL) plasma physics division and the Naval Center for Space Technology’s physicist and engineers are researching a technique for cleaning space junk at a low earth orbit (LEO) through an active debris removal (ADR) system.

The research specifies that the dust-based ADR system could be a an effective means of sweeping away dangerous, untraceable small orbital debris and control risks affecting satellites and space stations.

According to the NRL, orbital debris in LEO can travel over 8km a second, or 17,000mph and cause damage to space assets, including the International Space Station (ISS), the Hubble Space Telescope and several weather satellites, as well as destrroy solar arrays, instrument panels and solar shields.

Gurudas Ganguli, from Plasma Physics Division NRL space analysis and application section, said that hundreds of near-misses occur each year between orbital debris and operational satellites.

"Dust, similar to that which naturally fills the near-Earth environment, can be deployed artificially in a narrow altitude band to enhance drag on debris and force re-entry," Ganguli said.

NASA’s Orbital Debris Program Office revealed that LEO has nearly 21,000 orbital debris objects, which are about 10cm in diameter, and nearly 500,000 object particles between 1cm-10cm, while more than 100 million debris particles smaller than 1cm.

In accordance with the study conducted by US National Research Council (NRC) to evaluate NASA’s meteoroid and orbital debris programme, the debris are located at the ‘tipping point’ of LEO, which is the threshold for collision cascade.

"Dust, similar to that which naturally fills the near-Earth environment, can be deployed artificially in a narrow altitude band to enhance drag on debris and force re-entry."

The phenomenon is expected to significantly increase the likelihood of further collisions and increase the risk of maintaining space assets without clearing the debris.

NRL revealed that nearly 100t of cosmic dust, in the form of micrometeorites, is naturally released each day in the Earth’s environment; in addition, because of human space activity, a large quantity of dust is released into space, which will be too widely dispersed to affect orbital debris.

According to Ganguli, the dust following its deployment into orbit in the opposite direction to the debris trajectory can induce an enhanced drag, which would allow synchronising the rate of dust, as well as debris descent and allow for clearing large debris by deploying a modest amount of dust.

NRL said that the same ADR system concept, with a suborbital dust deployment, could be implemented to clear larger debris.

Image: The LEO has more than 100 million debris particles with size lesser than 1cm. Photo: courtesy of NASA Orbital Debris Program Office.