Launching hundreds of thousands of satellites will threaten space research, scientists warn

Satellite constellations, networks of multiple satellites that can number from a few dozen to tens of thousands, are interfering with scientific research using ground-based telescopes, but now a new study looks at how they might affect space-bound telescopes like Hubble.

The Hubble Space Telescope has produced some incredibly beautiful photographs of galaxies and nebulas that we have come to marvel at, but it’s also made incredible scientific discoveries, including measuring the rate of our universe’s expansion.

But that science could be threatened if all the proposed satellite megaconstellations — groups of thousands of satellites launched by companies like SpaceX and Amazon — come to fruition.

The authors of the paper published today in Nature looked specifically at Hubble, NASA’s SPHEREx — a near-infrared telescope that was launched last March — the European Space Agency’s proposed ARRAKIHS (Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys) and China’s planned Xuntian telescope.

The authors calculated that should the 560,000 proposed satellites be launched into orbit in the coming decade, roughly 39.6 per cent of Hubble images would be affected, and 96 per cent of the other three would be affected.

As satellites move across the sky, they create long streaks of light across any images telescopes take. They can also interfere with radio astronomy, as they "leak" electromagnetic radiation in low frequencies.

The authors calculated that the average number of satellites seen per exposure (which can be minutes long) would be 2.14 for Hubble, 5.64 for SPHEREx, 69 for ARRAKIHS, and 92 for Xuntian.

"I remember when … sometimes we saw like one satellite [a night], and it was very strange to see. Now this is getting more and more common, way too common," said lead author Alex Borlaff, a NASA research scientist at the agency’s Ames Research Center.

"In the last two, three years, we started seeing more satellites, even in some space telescopes, like Hubble. They pass in front of them because they share the same orbits."

Curious to see how these megaconstellations could impact astronomical research using space-based telescopes, Borlaff and his co-authors decided to do an estimation, resulting in their latest findings.

In 2019, there were roughly 2,000 satellites in orbit. Today, there are roughly 15,000, largely a result of SpaceX’s Starlink satellites. But the company is not alone: Amazon has just started with its Kuiper constellation (with plans for 3,200 satellites), OneWeb has 632 planned, and China is planning to launch 14,000. That’s just some of those proposed.

The reason for the boom in satellites has been due largely to the lower cost compared to a decade earlier, with reusable launch vehicles and smaller payloads, like CubeSats, which are roughly the size of a bread box.

And these satellites, like the ones from Starlink, are mainly providing and improving internet accessibility, particularly in remote locations across the globe. So they're unlikely to be going anywhere soon.

At the moment, ground-based observatories can pause their scientific research when they know a satellite may be passing in front of their telescopes, but it's a nuisance and takes more work, Borlaff said. And while space-based telescopes may be able to do the same, it's not the case all the time.