Space debris (SD) has been an issue since the very first spacecraft left from earth. Since the very inception, government and private companies have launched over 50,000 satellites in space and as such resulted to removing space debris in order to ensure a sustainable space environment.
Most studies have been central to removing relatively large SD such as upper stages of rocket and post operational aircrafts but this paper concentrated on small debris and removing it by orbital change and re-entry. The proposed method involved using a tethered plate satellite that would remove many small space debris successively by collision with the plate of the tethered mechanism.
This was termed feasible if the space debris was to move more slowly than the satellite containing the plate structure. This is due to the fact that an object suspended by a tether moves at the same orbital angular velocity as its center of mass. An altitude of about 1000km was the target since most space debris was situated within this region.
Analysis and calculations were also carried out as part of this research paper and it showed that at an altitude of 950km, inclination of 98.8⁰ and mean motion of 13.84 rev/day, the space debris deemed to be proximate to the plate when the distance between them is <10km and the velocity is <400m/s.
The procedure for the debris removal were as follows:
- Detect a SD item approaching within 10km
- Calculate the orbital maneuver required to cause the plate satellite to collide with the SD item
- Calculate the tether length at the time of collision and most certain check if all necessary conditions are satisfied then
- The debris removal system would change its orbit to collide with the SD item.
Conclusion: It was demonstrated that space debris could be removed repeatedly using this method and space debris with the same inclination and eccentricity similar to the debris removal system would be removed without damage.
SOURCES: Noboru Takeichi, Naoki Tachibana. A tethered plate satellite as a sweeper of small space debris (2021) https://doi.org/10.1016/j.actaastro.2021.08.051