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SpaceX Satellites Are A Problem For Astronomers

This long-exposure image shows a trail of a group of SpaceX's Starlink satellites passing over Uruguay on Feb. 7, 2021. (Mariana Suarez/AFP via Getty Images)
This long-exposure image shows a trail of a group of SpaceX's Starlink satellites passing over Uruguay on Feb. 7, 2021. (Mariana Suarez/AFP via Getty Images)

While eating al fresco with friends on a recent evening, Here & Now’s Peter O’Dowd saw a string of lights appear low in the night sky — one bright little dot after another zooming by above him.

He thought it was some kind of alien spacecraft invasion, but it turned out to be Elon Musk’s latest venture. Musk has launched nearly 2,000 low-orbit satellites into space to bring internet connectivity to remote areas.

But the constellation of Starlink satellites is alarming casual observers and professional astronomers. John Barentine, director of conservation for the International Dark-Sky Association, started thinking about the implications of having hundreds or thousands of satellites up in the sky at the same time after the first Starlink launch in May of 2019.

“In the next 10 years, we expect that the number of satellites orbiting the Earth will increase by more than an order of magnitude,” he says. “The Starlink program alone represents about 30,000 objects compared to the roughly 4,000 or so satellites that are in orbit around the Earth right now.”

The little moving lights show up in the images produced by telescopes, he says.

“If you’re observing a faint object in the distant universe and suddenly a satellite comes by, it sort of obliterates what you just saw,” he says. “It buries below this bright signal from the reflected sunlight the science data that you’re trying to get.”

Barentine co-authored a recent paper that found these satellites and small pieces of debris are making the night sky brighter. This could make astronomy a bit less efficient, he says.

“As you raise the background level of the night sky, you lower the contrast between the sky and the objects that we’re trying to see with the telescopes,” he says. “And so we have to expose longer to get the same amount of signal from these distant objects.”

In March of 2020, Musk predicted that Starlink won’t impact astronomy at all. If the satellites do impact the study of space, Musk said the company will “take corrective action.”

Starlink has tried to make these satellites less reflective by using a darker coating and testing an umbrella-like shade that would cut down on the reflection.

Some “encouraging early signs” indicate that Starlink’s efforts are helping, Barentine says. Researchers aren’t seeing the same brightness from satellites with these design modifications compared to the company’s early launches.

“They’re down to the point where you would need to be in a place with a relatively dark sky in order to see them. But they’re still there,” he says. “And the company has set itself a goal of reducing the brightness of the objects once they reach that final orbit to below the threshold of what the naked eye would observe.”

Astronomers are now looking for help. Barentine authored a report by the International Astronomical Union that was then submitted to the United Nations Committee on the Peaceful Uses of Outer Space.

Satellites are governed by the Outer Space Treaty of 1967, which the U.S. and many other countries have signed. The treaty created a “framework for international cooperation in the use of space,” he says, but its authors didn’t envision private companies using space in this way.

“We’re leaning on the [United Nations] to provide advice to the member states to hopefully regulate this in a sensible way through their own national laws,” he says, “so that we don’t have to wait for an advance in the treaty regime in order to see a beneficial effect in how space is being used.”


 Julia Corcoran produced and edited this interview for broadcast with Jill Ryan. Allison Hagan adapted it for the web.

This article was originally published on WBUR.org.

Copyright 2021 NPR. To see more, visit https://www.npr.org.