Black Marble 2016: Composite global map created from data acquired by VIIRS in 2016. Image courtesy of NASA/NASA’s Earth Observatory.
We’re focusing on the night sky this week, and particularly the impact satellites are having on astronomy. We’ve written before about how visible the Starlink constellations are to the naked eye, and AST SpaceMobile’s recently launched BlueWalker 3, which is in one of the brightest objects in the night sky. Working in Earth Observation, and other satellite industries, there is excitement when new satellites are launched giving new opportunities and possibilities. However, there is growing awareness of sustainability and sustainability is not just about carbon footprints and space debris. It is also about living in harmony with your environment and making sure you don’t do damage to other ecosystems.
Satellites, in particular, the mega-constellations such as SpaceX and OneWeb are having an impact on optical, infrared and radio astronomy observations. It is interesting, and positive, to see that SpaceX has come to an agreement with the United States National Science Foundation (NSF) to look at limiting their impact on astronomers. According to a statement released last month, NSF and SpaceX have agreed to collaborate on how best protect astronomy while also providing maximum internet access for communities across the United States. As part of this agreement, SpaceX has agreed several actions, including:
- Working on reducing the optical brightness of their satellites including: using dielectric mirror film, solar array mitigation, black paint that minimizes brightness and solar glint. These actions are particularly important as the new generation of Starlink satellites are larger than the previous incarnations.
- Maintaining orbits below 700 km altitude for their satellites.
- Providing more transparent and easily accessible orbit information for the Starlink constellation, so astronomers can understand their location and adjust observations accordingly.
- Agreed to analyze the impact of astronomical facility lasers on its satellites. Previously, ground-based facilities had been required to turn off their lasers when a Starlink satellite was nearby, but this requirement has been removed.
- As Starlink uses a radio band close to that used for radio astronomy, SpaceX have agreed to work with the radio astronomy community to ensure both can continue to operate effectively.
- Coordinating with NSF’s Office of Polar Programs to work to minimize the impact of Starlink on remote geographical radio astronomy sites in polar regions.
- SpaceX committed to work with NSF as interference arises or new challenges are highlighted by the astronomy community.
These concerns are, of course, global and last week in the UK the Royal Astronomical Society, UK Space Agency, and the Government’s Department of Business met for the Dark and Quiet Skies conference. It was expressed that with the increase in low earth orbit satellites approved for launch, that within a decade it will be satellites, rather than stars, as the predominant feature of the night sky.
While there are concerns about satellite’s impact on the night sky, it should be remembered that regulatory authorities approve the launch of all orbiting satellites, plus tens of thousands satellites still to be put into orbit. Commercial companies are continuing to launch, with the latest SpaceX launch occurred yesterday with 49 satellites on board. It was the third such launch of the year, and another three launches are scheduled for February.
Discussions, and agreements such as the SpaceX and NSF one, are welcome. However, such agreements are voluntary and there is no formal requirement on satellite operators to mitigate the impacts on astronomy. Voluntary regulation in various industries often proves ineffective, and it will be fascinating to see if the SpaceX agreement improves the situation and whether other constellation operators will follow suit.
