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Another canary in the collapsing coalmine.

A paper today in Nature by Borlaff et al. on the impact of ever-increasing numbers of satellites in low-Earth orbit on space telescopes like Hubble, SPHEREx, & CHEOPS today, & Xuntian & ARRAKIHS in the future.

The number of proposed satellites is eye-watering, & the effects on astronomy horrendous – there are wider effects on pollution of the upper atmosphere & safety of key orbital assets as well.

nature.com/articles/s41586-025…

#Science #SpaceScience


Satellite megaconstellations will threaten space-based astronomy - Nature

Rapidly growing satellite constellations pose a substantial threat to astronomical observations, with projections indicating that future space telescopes will have more than 96% of their exposures affected by satellite trails, necessitating urgent mi…
Nature
#science #spacescience
in reply to Mark McCaughrean

Mark McCaughrean
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Mark McCaughrean
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While the effect of megaconstellation comms sats on ground-based astronomy has been discussed extensively, the fact that some space telescopes are also affected has had less coverage.

This new paper extends work that I did with Sandor Kruk & a nice group of ESA summer students, assessing satellite trails seen in images taken by Hubble as a function of time – the number rose sharply after Starlink started to be launched.

That was published in Nature Astronomy in 2023:

nature.com/articles/s41550-023…


The impact of satellite trails on Hubble Space Telescope observations - Nature Astronomy

Harnessing the power of citizen science and machine learning, this study takes in 20 years of Hubble Space Telescope images, of which 2.
Nature
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Mark McCaughrean
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Mark McCaughrean
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That paper was preceded by another I was involved in led by Andy Lawrence, with many other astronomers including @sundogplanets & @planet4589, focusing on the wider environmental impacts of the the goldrush to monetise low-Earth orbit with massive constellations of wifi routers.

Also published in Nature Astronomy in 2022:

nature.com/articles/s41550-022…


The case for space environmentalism - Nature Astronomy

Crowded with satellites and debris, the orbital space around the Earth should be formally recognized as an ecosystem—like the ocean and the atmosphere—to ensure sustainable development and protection from irreversible damage.
Nature
@Prof. Sam Lawler @planet4589 (Jonathan McDowell)
in reply to Mark McCaughrean

Mark McCaughrean
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Mark McCaughrean
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For today's paper by Borlaff et al., Nature have also published a news article by Jenna Ahart, as well as podcast & a News & Views opinion piece by Meredith Rawls.

I'm quoted at the end of Jenna's piece, but as it's behind a paywall, you may not be able to see what I said, so I'll add it below.

You won't be at all surprised to discover that I'm very pessimistic about this issue, seeing it as part of a wider picture of environmental over-exploitation & collapse.

nature.com/articles/d41586-025…

A screenshot from a piece by Jenna Ahart in Nature about the impact of satellite megaconstellations on space-based astronomy. The text of the final two paragraphs reads: Sharing the skies Moving forwards, Borlaff hopes that astronomers and satellite companies can work together to share the skies. If future satellites occupy orbits lower than currently planned, for instance, they might not inconvenience astronomers so much. “We will need to find a way to coexist,” he says. Other researchers remain unconvinced that such coexistence is possible. It is “deeply naive” to think that astronomers can work around megaconstellations, says Mark McCaughrean, an astronomer at the Max Planck Institute for Astronomy in Heidelberg, Germany. “Too few people seem to care about the consequence of over-exploiting this heavenly resource.”

Satellite swarms set to photobomb more than 95% of some telescopes’ images

Planned megaconstellations would contaminate the view of the cosmos of four orbiting telescopes.
Ahart, Jenna
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Mark McCaughrean
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Here are the links to Meredith's opinion piece and Nature's podcast, for further background.

nature.com/articles/d41586-025…

nature.com/articles/d41586-025…

There's a pretty scary visualisation by Alejandro Borlaff in Meredith's piece showing what ESA's future ARRAKIHS mission would see in a single wide-field exposure if all currently proposed LEO constellations containing 560,000 satellites (!) actually get built. I've added screenshots here.

A simulated image of space containing a pair of large galaxies and many smaller ones.
The same field now with a simulation of satellite trails superimposed, as predicted from the parameters of currently proposed megaconstellations.

Even in space, telescopes can’t escape photobombers

Light reflected from satellites pollutes the images taken by telescopes orbiting Earth, as well as those on the ground. Without mitigations, this will only get worse.
Rawls, Meredith
This entry was edited (3 days ago)
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