Posted inCivil

NASA study assesses costs and benefits of orbital debris removal

An illustration of objects and space debris in Earth orbit.
An illustration of objects and space debris in Earth orbit. Credit: ESA/ID&Sense/ONiRiXEL, CC BY-SA 3.0 IGO

LAUREL, Md. — A NASA study concluded that some methods of removing orbital debris could pay for themselves within a decade by reducing the costs and risks borne by satellite operators.

The study, released March 10 by NASA’s Office of Technology, Policy and Strategy, examined the costs of several approaches to removing both large and small debris and the benefits they offered to satellite operators by reducing the number of avoidance maneuvers and losses of satellites damaged or destroyed by debris collisions.

NASA billed the report as the most rigorous cost-benefit analysis to date of orbital debris remediation, noting that debris removal analyses had largely focused on emphasizing sustainability and “moral responsibility” for doing so. “Given the substantial upfront expenditures required to develop and deploy remediation capabilities and the potential delay in receiving benefits, these motivations do not appear to be sufficient to incentivize immediate action,” the report stated.

The analysis, which looked at both the cost of establishing various approaches to removing debris as well as the costs incurred by satellite operators from debris, found the most effective approaches involved ground- and space-based lasers to remove large amounts of small debris between 1 and 10 centimeters across. Both laser systems would create benefits that exceed their costs within a decade.

The other effective approaches involved “just-in-time collision avoidance” involving the largest debris objects, using rockets or lasers to nudge such debris to avoid collisions with satellites or other debris. Such approaches could have net benefits almost immediately, or no more than a few decades in a worst-case assessment.

Other approaches included in the study could take much longer to realize a net benefit. Reentry of larger debris objects could break even in as little as 20 to 25 years, but in worst-case scenarios might take close to a century to yield benefits. The study found similar timeframes for “sweeper” spacecraft that would physically remove small debris. It also examined recycling debris by turning it into propellant, but found breakeven times of a few decades, in part because of large upfront research and development costs for the technology.

The report acknowledged one problem with using lasers to remove debris is the perception that such systems could also be used as weapons. The study concluded that the power of debris-removal lasers would be too low, by a factor of 1,000, to be effective as a weapon against active satellites, “though perceptions may be harder to navigate.”

One interesting finding of the report is the relatively small costs that debris imposes on satellite operators today. The model NASA developed for the report, which was limited to U.S. operators, estimated annual costs on such operators of only $58 million a year, a figure dominated by military as well as civil operational satellites, like Landsat and polar-orbiting weather satellites.

“We found that most satellite operators do not incur much cost from conjunction assessments or collision avoidance maneuvers,” said Bhavya Lal, NASA associate administrator for technology, policy and strategy, in a speech at the American Astronautical Society’s Goddard Memorial Symposium March 10 that coincided with the release of the report. “The key takeaway here is that the risk to satellite operators need not increase at the same rate as orbital debris increases.”

That didn’t mean, though, that remediation approaches like those NASA studies should not be considered, she argued. “Conventional wisdom has been that prevention is more valuable than cure, that debris mitigation is more critical than remediation,” she said, but warned those efforts to mitigate the creation of new debris will likely see diminishing returns in the coming decades.

‘The challenge is to assess the effectiveness of mitigation, tracking, characterization and remediation in a way that enables apples-to-apples comparisons among risk reduction technologies,” she said. “With such information, we can understand the most effective portfolio of risk reduction.”

Lal said that NASA planned to organize a roundtable among various stakeholders to get feedback on the study before starting a second phase that will improve the model and incorporate even smaller debris.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...