Prof. Sam Lawler5h ago

Interview done! Now time to dig in to this really thorough, horrifying paper by Olivier Hainaut about what the night sky will look like with future satellites https://arxiv.org/pdf/2604.09427

This is similar to the kind of modelling that I've done with my collaborators, but using totally different code and methods. This is how science works! Predictions are being tested, and unfortunately for the sky, this paper's predictions line up with ours. It's bad.

Show threadProf. Sam Lawler5h ago
The main conclusion is that *if* satellite operators could actually make their satellites fainter than mag 7 (as Starlink promised to do and hasn't managed to do yet because they keep making their damn satellites bigger and on lower orbits) and there's "only" tens of thousands, the night sky and astronomy research are in pretty good shape, actually. (Unfortunately this is still a pipe dream, because nobody has managed to get fainter than mag 7) https://ui.adsabs.harvard.edu/link_gateway/2025MNRAS.544L..15M/PUB_PDF
Show threadProf. Sam Lawler5h ago
This figure shows that SpaceX's million data center stupid idea would result in dozens of satellite streaks per exposure (from the FORS2 instrument at Paranal) over half the sky, even an hour after nautical twilight. The part of the sky where you could still do astronomy research would be extremely limited.
Show threadProf. Sam Lawler5h ago
They also model Reflect Orbital's stupid idea, showing that with giant mirrors in orbit, the entire night sky worldwide would become as bright as in a typical suburb, even if you're outside their beams.
Show threadProf. Sam Lawler5h ago

"A mega-constellation of one million or more satellites would fundamentally alter observing conditions, ensuring that most exposures contain multiple trails during a large fraction of the night. The field-of-view losses then rise to 10%–20%, making satellites the dominant source of data loss, ahead of weather and technical downtime."

But don't worry, we'll be in full Kessler Syndrome long before we get to one million satellites! 😭

Show threadszakib4h ago
@sundogplanets Has anyone modelled the Kessler syndrome sky? I wonder what it would look like.
Show threadProf. Sam Lawler
@szakib I've thought about doing that simulation, and decided it was too depressing
3:53pmWeb
Show threadszakib3h ago
@sundogplanets yeah...