SpaceX is working hard to dim its Starlink satellites to minimise their effects on astronomy, but so far the company’s efforts haven’t worked as astronomers had hoped. That might mean that there is a difficult choice ahead: high-speed internet via satellite megaconstellations, or ground-based astronomy unmarred by bright streaks.
So far, SpaceX has launched more than 4200 Starlink telecommunication satellites, the majority of which are still in orbit – they make up more than half of the active satellites orbiting Earth. The firm intends to launch 42,000 Starlinks total, and several other companies around the world have plans to create similarly huge constellations, with many more planning smaller clusters.
The detrimental effects of these satellites on astronomy is well documented: they increase the brightness of the night sky by as much as 10 per cent, creating bright trails of light, and some telescopes could end up with half of their images becoming unusable.
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“If it goes in the direction it looks like it’s going, I think it’s going to be an existential problem for ground-based astronomy, and a large fraction of the effort in ground-based astronomy will go into dealing with the satellites, effort that is now going into doing science,” says at the Harvard-Smithsonian Center for Astrophysics in Massachusetts. “You’re going to have a large number of failed projects, a large number of projects that take far more observing than expected.”
SpaceX has tried two methods to mitigate the problem so far. The firm painted one satellite black so that it would reflect less light in a test called DarkSat, but the satellite ended up overheating because of all the light that was being absorbed. Then, it put a sunshield on a satellite to block the reflections in a test called Visorsat, but has shown that Visorsat was still, for the most part, bright enough to be seen with the naked eye.
Visorsat has since been retired because it interfered with Starlink’s laser communications system, and SpaceX is trying out some new methods on its V2 satellites. “I think it’s more than a show of good faith – they’ve put quite a lot of money and effort into it,” says at the University of Michigan. “How well it works remains to be seen.” SpaceX didn’t reply to a request for comment.
Even if SpaceX’s mitigations do work, and even if the other major companies planning megaconstellations follow suit, there are still smaller organisations for astronomers to worry about. Most of those smaller firms are planning relatively small constellations of a few tens of constellations, but there are signs that might be temporary – one company, E-Space, has requested permission through the government of Rwanda for 300,000 satellites.
“Trying to knock this problem down on an operator-by-operator basis doesn’t seem to be the way to go,” says McDowell. “All these mitigations will decrease the severity – they won’t make the problem go away.”
Many other astronomers have publicly agreed that regulation is needed, and satellite operators may be rushing to beat it. “I think there is a fear among many of them that there might be tighter regulation coming, so they want to get out ahead of that so that they can shape it ahead of time,” says Seitzer.
Until that regulation happens, if it does, astronomers and the space industry are at a bit of an impasse. “Can we have both? Can we have both fast internet everywhere in the world and a dark sky? I think the court is still out on that,” says Seitzer. The fact that, even with all its best efforts, SpaceX still hasn’t managed to dim its satellites enough to meaningfully mitigate their effects on the night sky and astronomy is not a good sign.
Ultimately, McDowell says, it is about humanity deciding how we are going to treat space, and how – or whether – we decide to enforce those values. “It’s about the culture of how we industrialise space and whether we do it in a sustainable and environmentally responsible way, or whether we go out and just throw as much up there as we can and just live with whatever that means,” he says. “We’ve seen how that’s gone so far on Earth.”
