Elon Musk's Starlink satellites got 'invisibility' upgrades. What do astronomers say?

Astronomers have also organized against the company, stating that the sunlight reflecting off Starlink’s satellites impedes their ability to conduct research at crucial times — such as astronomical twilight (the period of the day when the Sun is below the horizon but some of its light is still being scattered and bounced back to observers), when a great deal of research on near-Earth asteroids is conducted.

Now, SpaceX has released a new document detailing the steps it aims to take in its effort to reduce its impact on the astronomical community.

We spoke to a number of leading astronomers to get their thoughts on whether SpaceX's latest update is a positive step and whether it will improve relations between the private space firm and the global astronomical community.

SpaceX updates its ‘brightness mitigation’ efforts

SpaceX previously planned to add “sun visors” to all of its satellites, though it ultimately conceded that these caused too much drag, meaning each satellite would have to burn more fuel to stay in orbit. This, and the fact that the sun visors also blocked laser links on the satellites, caused the company to scrap its initial plans to deploy the technology across its entire constellation.

This month, however, SpaceX released a new document detailing a host of recent upgrades and measures for its Starlink satellites that should, in practice, make them “invisible to the naked eye”. These updates will be rolled out for its current-gen Starlink satellites, as well as for Starlink 2.0 satellites, which will be launched using SpaceX's Starship rocket.

The new "brightness mitigation" updates include a mirror film — which SpaceX says it will also eventually sell to third parties — that makes the satellites less reflective and an agreement to turn the satellite’s solar cells away from the Sun at specific times. The space company also announced it would use darker, less reflective paints on parts of its satellites where the new mirror film could not be attached.

Astronomers respond to SpaceX’s Starlink promise

We reached out to a number of astronomers to see what they think about SpaceX’s latest update, including Meredith Rawls, Ph.D., an astronomer at the University of Washington. “I both think it is a positive step and that they are not doing enough,” she said.

Rawls recently published an article in the journal Nature titled 'The Case for Space Environmentalism', and she is part of the newly-formed International Astronomical Union Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS).

She also pointed us towards a recent statement by the IAU CPS saying SpaceX’s new upgrades are “a real demonstration of corporate good citizenship, representing a significant investment of engineering resources in both hardware and operational modeling to reduce reflected sunlight hitting telescopes on the ground.” They do also note, however, that more work is needed “on remaining concerns such as minimizing bright transients, the impacts on radio astronomy, and mitigation of aggregate effects of a large and growing constellation.”

Samantha Lawler, an astronomer at the University of Regina, Canada, who’s also working to spread the word and fight the impact of Starlink on astronomy, told IE she thinks “it is absolutely fantastic that SpaceX appears to be taking the light pollution issue seriously.

"But in the past, they have made grand statements about making Starlink satellites fainter without meeting their promises, so I will believe it when I see it (or hopefully, when I don't see the satellites anymore!)”, Lawler added, likely referring to SpaceX’s scuppered sun visor plans.

A promising first step, but concerns remain

Lawler also noted that there seem to be some important omissions in the document — though she did concede at the time of our interview that she had only had time to skim over the main points. “Two important points that I did not see in the document on a quick skim-through is any mention of mitigation for atmospheric pollution by satellite reentry or any plans to deal with solar storms,” Lawler said. “These are both extremely important issues, as they affect our atmosphere.”

Lawler pointed us towards a recent study showing that the number of rocket launches perfectly correlates with noctilucent clouds ('night-shining' clouds – thin clouds up to 50 miles (80 km) above Earth's surface). This means that rocket launches are already affecting our upper atmosphere, and the scientific community is starting to strengthen its knowledge of the effects of mega-constellation launches.

Aaron Boley, an associate professor of astronomy and astrophysics at the University of British Columbia, agrees that the environmental impact of satellite launches in the upper atmosphere may eventually become an even greater concern than its impact on astronomy. Boley co-wrote a paper on the potential environmental effects of mega-constellation reentries. According to the paper, the issue stems from the fact that each Starlink satellite stays in orbit for a few years, after which they burn up on reentry, depositing huge amounts of aluminum into the upper atmosphere. We know remarkably little about the effect this will have in the long term.

“A lot more work on this topic is needed, including measuring the impacts,” Boley told IE over email. “One of the main issues for sustainability is that plans for large satellite constellations are being made in more or less isolation.” In other words, “the cumulative use of space is not being considered,” Boley continued. “This is leading to many problems, including space traffic management, debris generation, reentry risks, and light pollution.”

“Until cumulative impacts from use are considered,” Boley said, “it is my view that we will not achieve a sustainable level of development, and we can expect a degradation of the Earth and space environments, including our ability to use the orbital environment.”

The astronomers we talked to all seem to be in agreement when it comes to SpaceX’s new announcement regarding their plans for Starlink brightness mitigation. As Lawler put it, “overall, I'm hopeful seeing this statement, but they still have a lot of work to do to make these satellites safer and darker.”