Why it matters: Astronomers have previously complained that satellites partially block images from ground-based space telescopes. However, visible light is not the only part of the electromagnetic spectrum that astronomers observe, nor is it the only place where satellites can threaten their work. Precautions may be necessary to protect radio observations.
A group of researchers has begun to raise the alarm about how the increasing number of satellites in our sky is interfering with ground-based radio telescopes. The astronomers want lawmakers to designate special zones where scientists, tech companies and others can figure out how to share the spectrum.
When most people think of astronomy, they probably envision the amazing images of distant stars and galaxies taken by optical telescopes, which collect visible light for their observations. However, other important information about deep space comes from radio and infrared signals.
Astronomers’ famous image of the galaxy Messier 87 released in 2019, the first image of a black hole, was constructed using information from an array of eight radio telescopes spread across Earth. Conventional methods would have required a telescope as big as Earth.
The recent discovery of twin exoplanets, possibly the first aquatic worlds researchers have found, was made possible by the Hubble telescope and the Spitzer infrared telescope. Infrared information helped astronomers determine the volume and density of planets, leading to the water world hypothesis.
The researchers say that signals from the weather, the Internet, GPS and other satellites could interfere with the data being received by radio telescopes. Currently, quiet zones on the ground restrict the strength and frequency of radio communications for radio telescopes to operate. However, the laws that govern them may not protect against the growing number of communications satellites.
SpaceX’s Starlink Internet satellites could become a source of interference. Astronomers have complained that the company’s satellites could fill the visible night sky. In one case, a Starlink satellite created a beam of light in a space photo by moving across a telescope’s field of view during its long exposure period.
However, SpaceX is cooperating with the National Science Foundation to solve the problem of visual and radio interference. The company wants to make its satellites less reflective and narrow the focus of its communication frequencies. The company also said that it would run further tests to find more solutions.
The researchers point to a recently published paper on radio telescope interference that calls for radiodynamic zones. These would function as radio quiet zones, but would also serve as experimentation platforms for scientists, developers, and other groups to figure out how to work with each other.