Large debris removal mission in LEO based on hybrid propulsion

During the last 40 years, the mass of orbiting objects increased at the rate of about 145 metric tons annually, leading to a total of approximately 7000 metric tons. Most of the cross-sectional area and mass (97% in low Earth orbit, LEO) is concentrated in about 4500 intact objects, i.e. abandoned spacecraft and rocket bodies, plus a further 1000 operational spacecraft. Numerical simulations show that the most effective way to prevent an exponential growth of the cataloged debris population would be to remove enough cross-sectional area and mass from densely populated orbits. According to the most recent NASA results, the active yearly removal of approximately 0.1% of the abandoned intact objects would be sufficient to stabilize the cataloged debris in LEO. The typical targets for removal would have masses between 500 and 1000 kg, for spacecraft, and of more than 1000 kg, for rocket upper stages. This paper investigates a space mission concept for active removal of abandoned Cosmos-3M second stages from LEO. The proposed concept relies on flying a multi-removal space platform carrying a number of Hybrid Propulsion Modules (HPMs). After capture, a HPM is installed on the debris, which is then de-orbited in a controlled fashion. The estimated mass of a single HPM results about 200 kg, making possible a multi-removal mission by means of a low-cost class-launcher.