According to NASA, there are more than 500,000 pieces of debris in orbit that are being tracked by the space agency. It’s a serious situation. The debris travels at such a high rate of speed that even a small piece of it can do significant damage if it collides with an orbiting satellite or spacecraft. To help mitigate this threat of collision, a team of researchers from Tsinghua University in Beijing, China have come up with a solution for removing space debris. Instead of zapping the material with a laser to reduce its size, as some have proposed, the Chinese scientists want to remove the space junk completely by using it as fuel.
The idea behind the Chinese plan is simple — heat any material to ionize it and then use the ions as a propellant by moving them through an electric field. According to the proposal, the trash-eating spacecraft will capture small debris, sized less than 10 centimeters in diameter, using a net. This material then will be transferred to a ball mill that will use abrasion-resistant balls to grind the space junk into a powder.
The powder will then be fed into a propulsion system that separates the positively charged ions from the negative ones. The positive ions then will be passed through a strong electric field that will generate thrust as they are expelled outside the spacecraft. This form of continuous thrust can be used to perform orbital maneuvers or to collect additional space junk.
The proposal is promising in theory, but it may need refinement in practice. Space junk is a mixed bag of material, which means the spacecraft’s fuel source will vary based on what type of garbage is being collected. The resulting thrust will fluctuate based on the density of the debris field, the type of powder being produced, and the ionic properties of the material being collected.
The system also only provides propulsion, so the spacecraft will still need a separate power source. The researchers propose either a solar or nuclear power solution, but they fail to address safety concerns associated with sending a nuclear power reactor into orbit. Despite these shortcomings, though, the idea is likely to stimulate discussion, and it is this type of discourse that eventually will lead to a viable solution.