A study by US researchers has concluded that satellite operators need to pay a fee for space debris removal if the orbital region around Earth is to remain safe and usable.
Orbital debris, such as spent rockets and old satellites, pose a growing problem for operators in space as even tiny pieces can disable and destroy spacecraft. The ESA estimates that there are a million objects larger than 1cm orbiting the Earth and 130 million objects larger than 1mm.
Space agencies are researching the issue, and companies such as ClearSpace are developing fleets of robots to clean up space debris. However, as technologies develop questions remain about who will fund clean-up activities.
Researchers at the Stevens Institute of Technology in New Jersey, USA investigated ways to create commercial opportunities for space operators and debris remediators to clean up the dangerous junk. “We wanted to see if there’s any potential to having commercial players interested in removing the debris,” said Hao Chen, lead on the research and assistant professor at the department of systems engineering, Stevens Institute of Technology.
Space debris removal scenarios
The study analyzed three possible scenarios of debris clean up: controlled reentry back to earth, uncontrolled reentry back to earth, and recycling in space. All three methods would require a space debris remediation satellite – a vehicle designed to capture and remove space junk from orbit.
In the uncontrolled reentry scenario, which is the cheapest option, the remediation service vehicle grabs the debris from the orbit path it flies in and brings it down to about 350km away from earth.
In the controlled reentry scenario, the remediation service vehicle would bring the debris closer to Earth, to about 50km. “Controlled reentry is more expensive because the servicer needs to bring the debris down closer to earth and then fly up again to get the next piece of debris. That consumes more energy and more fuel than an uncontrolled reentry,” Chen said.
In the recycling scenario, the debris is transported to a recycling center in space. The transportation adds costs, but energy is also saved by reusing aluminum, the metal most commonly used in spacecraft, instead of bringing it up from earth. “It takes about $1500 per kilogram to launch anything from Earth to space,” explains Chen.
Space debris removal funding
Next Chen and collaborators analyzed ways to incentivize companies into space debris removal. They used Game Theory and Nash Bargaining Theory, developed by mathematician John Nash, to determine the fairest deal for operators and remediators.
“The debris remediators pay for the missions, the technology, and the actual work. Without some kind of financial incentive, they don’t really gain anything from it — they bear all the costs while others reap the benefits,” said Chen.
Meanwhile, space operators stand a lot to gain from debris removal. Their satellites can operate more safely and efficiently, saving money on fuel and operations, since they don’t have to make extra maneuvers to avoid collisions. “However, they don’t actually do anything to remove the debris themselves – they just enjoy the cleaner, safer environment,” Chen pointed out.
To solve this problem, Chen’s team proposes creating fees that space operators would have to pay.
“We will need an agency to create an incentive for the debris remediators,” said Chen. “The money should come from the people who enjoy all those benefits.
“Our analysis shows that there is a surplus to be generated from the remediation of orbital debris, and that this surplus can be shared by space operators and debris remediators.”
Without such a solution, the space debris dangers will only continue growing, generated by the current and future objects left in orbit, Chen notes. “That is what’s needed to move us closer to a space industry that is safer, more sustainable, and still profitable.”
Space Logistics Analysis and Incentive Design for Commercialization of Orbital Debris Remediation was published in the Journal of Spacecraft and Rockets in October. The research is being presented this month to NASA, which funded the study.
