Aerospace Corp. raises questions about pollutants produced during satellite and rocket reentry

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This article was updated on Dec. 14 at 11:06 pm with comments from one of the study’s authors William Ailor, technical fellow with the Aerospace Corp.’s Center for Orbital and Reentry Debris Studies. 

SAN FRANCISCO – As the combined mass of satellites in orbit climbs, research is needed to better understand the environmental impact of the portions of satellites and launch vehicles that eventually reenter Earth’s atmosphere, according to an Aerospace Corp. poster presented at the virtual American Geophysical Union fall meeting.

The Aerospace Corp. conducted a preliminary study to assess potential environmental impacts as the population of satellites in orbit continues to grow. The study includes a model of the total future mass of satellites in orbit based on the Federal Communications Commission filings and press releases, including constellations proposed by Boeing, AST&Science, Kuiper, Mangata, o3b, Telesat, Viasat, OneWeb and Theia in the poster, Environmental Impact of Satellites from Launch to Deorbit and the Green New Deal for the Space Enterprise.

If all those constellations materialize, the annual mass of satellites reentering Earth’s atmosphere eventually could rise from a current level of roughly 100 metric tons to between 800 and 3,200 metric tons. Launch vehicles reentries could account for another metric ton per year.

Researchers estimated that 60% of rocket bodies and 60 to 90% of satellite mass burns up during atmospheric reentry. Aluminum is likely to be one of the most common materials to burn up during reentry, according to the poster by Lee Organski, Cayman Barber, Shawn Barkfelt, Madison Hobbs, Roy Nakagawa, Martin Ross and William Ailor.

The study was based on limited data “because traditionally, quantifying environmental impacts of spaceflight has been thought to be of negligible concern, not dissimilar to how airplane emissions were assumed inconsequential before air travel became commonplace,” William Ailor, technical fellow with the Aerospace Corp.’s Center for Orbital and Reentry Debris Studies, said by email. “Albeit imprecise, we believe our rough estimates are a useful starting point, and that the environmental impacts of rocket emissions, space debris and re-entry plumes warrant attention given the significant increase in space activity in recent years.”

Much attention is paid to the danger to people on the ground and aircraft in flight from satellite and rocket components that survive reentry. A study published in January 2020 assessed the potential risk and estimated that 10 to 40% of satellite mass survives reentry and is a potential hazard to aircraft and people. That study did not account for the tens of thousands of additional satellites companies plan to launch in the next few years.

In contrast, there is a lack of data and research on what happens to the estimated 60 to 90% of satellite mass that remains in the atmosphere.

“Our preliminary work suggests that given the present and anticipated increase in large satellite constellations, there is potential for environmental impact, and further study is therefore recommended. “Our preliminary work simply suggests that given the present and anticipated increase in large constellations, there is potential for environmental impact, and further study is therefore recommended,” Ailor said.

Reentering satellite particulates could warm Earth’s atmosphere but “without precise modeling the exact extent is unknown,” according to the poster. In addition, reentering space debris could contribute to the depletion of Earth’s ozone, the poster warned.

“It is concluded that the marked increase in these pollutants calls for the close tracking of mass flux, further research on the particulate distribution and radiative forcing, general research into reentry physics, and a study of possible solutions to mitigate the issue,” according to the poster.

It is worth noting, Ailor said, “that the space enterprise has seen little environmental oversight, and continuing space operations without reliably quantifying and mitigating for its environmental impacts has costs.”

As an example, Ailor cites light pollution from the SpaceX Starlink constellation, which spurred discussion about U.S. government oversight of satellite constellations. “Therefore, more analysis is warranted to appropriately quantify and account for environmental impacts along the entire space supply chain to ensure both terrestrial and space sustainability,” Ailor added.