The International Astronomical Union has warned against the rise of satellite constellations in Earth's night sky, such as SpaceX's Starlink system, since their brightness and noise could hamper future scientific research.
“[We’re] concerned about these satellite constellations,” the union said in a statement this week. “The organisation, in general, embraces the principle of a dark and radio-quiet sky as not only essential to advancing our understanding of the universe of which we are a part, but also as a resource for all humanity and for the protection of nocturnal wildlife.
“We do not yet understand the impact of thousands of these visible satellites scattered across the night sky and despite their good intentions, these satellite constellations may threaten both.”
A big problem with these satellites, designed to blanket cover the world with internet broadband connectivity, is their highly reflective surfaces. The 60-unit Starlink system, lofted into orbit last month, look like a moving string of lights as the glow from the Sun bounces off them before sunrise and after sunset. That may sound pretty, but it’s not a sight that astronomers want to see.
Alex Parker, a senior research scientist and astronomer working at the Southwest Research Institute, a nonprofit R&D organisation in Texas, posted a picture of what the view looks like for NASA’s Hubble Space Telescope.
For no reason at all, here's what it looks like when a satellite goes through Hubble's field of view whilst you are trying to image something in the distant solar system. pic.twitter.com/eLWR1ncdqx— Alex Parker (@Alex_Parker) January 25, 2018
The bright white diagonal slash is caused by the satellite blocking out the distant stars in the background. This interference stops astronomers being able to observe parts of space at certain times.
These communications satellites also transmit signals at a frequency that is read as noise by radio telescopes on Earth. The interference makes it potentially difficult for astronomers to image black holes and other objects, or study supernova explosions and pulsars, or detect incoming asteroids.
These problems will only get worse as more low-Earth orbit satellites are shuttled into space. Up until last year, there were only 200 of them, but that number is shooting up. Although the IAU didn’t name and shame any companies, the statement was posted weeks after SpaceX unloaded scores of Starlink birds in space.
Third time's a charm? SpaceX hopes to launch 60 Starlink broadband sats into orbit tonightREAD MORE
It’s part of CEO Elon Musk’s plans to beam low-latency, high-bandwidth broadband internet to folks on the ground around the planet. He has his eyes on building a whole fleet of Starlink satellites that number up to 12,000 units.
As the sky gets crowded with objects, it also increases the risk of a collision between satellites that would kickstart a chain reaction that would litter space with debris. The scenario was first proposed by Donald J. Kessler, a retired NASA veteran, and later named the Kessler syndrome.
Satellites move at colossal speed, giving them a lot of kinetic energy. If they collide or break up then the chunks of debris speed off out of the old orbit and could hit other objects in space.
Kessler warned that once this started it could kick off a chain reaction as debris causes more crashes until the whole orbital plane is full of high-speed junk - think the opening minutes of the film Gravity. In a worst-case scenario we could lose all satellites and make it nearly impossible to put any more up, not to mention destroying most of our space telescopes.
“Satellite constellations can pose a significant or debilitating threat to important existing and future astronomical infrastructures, and we urge their designers and deployers as well as policy-makers to work with the astronomical community in a concerted effort to analyze and understand the impact of satellite constellations,” the IAU concluded. ®