On Thursday, May 23, Elon Musk’s SpaceX successfully launched its first 60 Starlink satellites, a planned mega constellation of satellites designed to beam internet from space to the world. But since footage emerged of the train of satellites in the night sky, astronomers have been up in arms at the impact Starlink could have on our views of the cosmos.
Starlink is designed to eventually consist of 12,000 satellites, orbiting at altitudes of about 550 kilometers and 1,200 kilometers. SpaceX is one of nine companies known to be working on global space internet, and already concerns have been raised about space junk. Now astronomers too are worried about what the future may hold.
“The potential tragedy of a mega-constellation like Starlink is that for the rest of humanity it changes how the night sky looks,” says Ronald Drimmel from the Turin Astrophysical Observatory in Italy. “Starlink, and other mega constellations, would ruin the sky for everyone on the planet.”
Following the Starlink launch, several observers – including amateur astronomer Marco Langbroek – captured footage of the satellites in orbit. All 60 were deployed in a train, one behind the other, but astronomers were surprised that the satellites shone brighter than many had expected them to.
“What I had not anticipated was how bright the objects were and how spectacular a view it would be,” says Langbroek. “It really was an incredible and bizarre view to see that whole train of objects in a line moving across the sky.”
SpaceX had kept the logistics of each satellite under wraps prior to the launch, but following the launch it was revealed that each satellite had a relatively large solar panel, perfect for not only gathering but reflecting sunlight back to Earth. This means anyone looking up at the stars, from any location on Earth, would always have the final Starlink constellation in view, for better or worse.
“It turns out that these satellites are easy to see with our own eyes, much brighter than we were expecting,” says astrophysicist Darren Baskill from the University of Sussex in the U.K. “If we can see them with our eyes, that means they are extremely bright for the latest generation of large, sensitive ground-based telescopes.”
Such telescopes include the Large Synoptic Survey Telescope (LSST), currently under construction and designed to take wide sweeping views of the night sky to study a variety of bodies such as asteroids and comets.
While the true impact of Starlink isn’t known yet, it’s thought the LSST may have to deal with one Starlink satellite every few images, notes astrophysicist Bruce Macintosh from Stanford University in the U.S., resulting in a streak through the image. Such issues are not new to astronomers, but the sheer number of Starlink satellites is cause for concern.
“Part of the knee-jerk reaction across the astronomy community after the launch of the Starlink satellites was purely caused by a lack of information,” says astrophysicist Jessie Christiansen from the California Institute of Technology (Caltech) in the U.S. “A significant amount of the outcry could have been avoided if there had been an impact study done in advance.”
During the dead of night the satellites are unlikely to be visible, as they will be in darkness with no sunlight to reflect. But it’s in the hours after sunset and before sunrise that people are most worried, when the thousands of satellites will be reflecting light from orbit and, it appears, clearly visible to anyone looking up.
Another concern is not just for visual astronomy, but radio astronomy too. Each satellite will emit radio signals in order to communicate with Earth, and for astronomers that rely on radio waves to study the universe – such as the first image of a black hole revealed last month – Starlink may bring with it new complications.
“Radio astronomers are even more concerned as the satellites are transmitting in the 10.7-12.7 GHz band, which includes the spectral lines of water among other things,” says space archaeologist Alice Gorman from Flinders University in Australia. “Radio astronomers fight daily to protect critical observation bands, and this is only going to get worse.”
Musk, to his credit, has responded to some of the concerns on Twitter. After initially seeming to misunderstand how and why the International Space Station (ISS) is visible in the night sky, he noted that SpaceX was looking into how to mitigate the effects of Starlink satellites on astronomy.
“Sent a note to Starlink team last week specifically regarding albedo reduction,” he said. “We’ll get a better sense of value of this when satellites have raised orbits and arrays are tracking to sun.”
He also implied that the ultimate goal of Starlink – bringing internet to the 3.3 billion people in the world who are offline, and using that money to fund SpaceX’s missions to Mars and beyond, albeit with an unclear market on how many of those can afford space internet or want to be online in the first place – was a “greater good” than any impact on astronomy.
“Potentially helping billions of economically disadvantaged people is the greater good,” he said. “That said, we’ll make sure Starlink has no material effect on discoveries in astronomy. We care a great deal about science.”
It’s clear, however, that much work will still need to be done to allay the concerns of the astronomy community. While some may point to the benefits services like Starlink could bring, others will be quick to point out the irrevocable impact this could have on human culture.
“I’m not so worried about astronomy per se,” says Drimmel. “I’m worried that what inspired me to become an astronomer is at risk.”
While those initial images of the train of satellites were impressive, the possibility of having so many satellites constantly visible is somewhat alarming. Astronomers may well be able to mitigate the impact of Starlink and other satellites (several teams are already working on models to see how that might be done), but the night sky itself may change forever as a result.
“With Starlink, we are expecting at least 100 satellites to be visible at any one time [at any location on Earth],” says Baskill. “Soon, even those fortunate to experience a truly dark site will find it filled with a haze of metal, slowly swarming across the night sky.”
