A new study demonstrates that SpaceX’s Starlink satellites are emitting radiation into the night sky as they circle Earth, which may be hindering astronomers’ efforts to detect radio signals from space.
Radio waves are sent and received by all satellites, including those in SpaceX’s rapidly expanding Starlink constellation, in order to communicate with their on-ground operators. Radio astronomers have been aware of this for a long time, and they can reduce the impact that these controlled beams have on their work by avoiding the locations of these satellites or taking into account the signals when making calculations.
However, researchers have demonstrated in a new study that was published on July 3 in the journal Astronomy & Astrophysics that Starlink satellites also produce unintended and previously unknown radio signals that are distinct from the signals that they send to and receive from our planet. A new issue in this area of research arises when some of these signals overlap with those detected by radio telescope dishes.
According to a statement released by study lead author Federico Di Vruno, co-director of the International Astronomical Union’s Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference, the unintended radiation leak had previously been theorized, but this is the first time it has been observed directly.
Related: The Low-Frequency Array (LOFAR) telescope, which is an array of radio dishes located primarily in the Netherlands as well as in seven other European countries, was utilized by the researchers in the study to closely monitor the emissions of 68 Starlink satellites. Geomagnetic storm causes 40 SpaceX satellites to fall to Earth.
The team discovered that 47 of the satellites were releasing radiation unintentionally at a frequency of 110 to 188 megahertz. In the statement, study co-author Cees Bassa, an astronomer at the Netherlands Institute for Radio Astronomy, said, “This frequency range includes a protected band between 150.05 and 153 MHz that is specifically allocated to radio astronomy by the International Telecommunications Union (ITU).”
Nonetheless, SpaceX isn’t disrupting any norms in light of the fact that the ITU’s regulation just keeps earthbound based radio sources from communicating in these frequencies close to radio telescopes.
SpaceX probably isn’t the only one to blame; The researchers anticipate finding similar emissions from numerous other LEO satellites. As the number of private satellites in LEO continues to rise dramatically, the issue could also get worse. When the data were taken, there were only 2,000 Starlink satellites in low-Earth orbit (LEO), but there are now over 4,000.
Gyula Józsa, a co-author of the study and an astronomer at the Max Planck Institute for Radio Astronomy in Germany, stated in the statement, “Our simulations show that the greater the constellation, the more important this effect becomes as the radiation from all satellites adds up.” This makes us even more concerned about the planned constellations as well as the existing constellations.”
The researchers wrote in the statement that they have already begun discussions with SpaceX regarding how the company can assist in the future in mitigating the issue, and that these discussions have thus far advanced in a positive direction. They added, however, that the issue will need to be considered by a lot of other private businesses as well. The teams want new rules that will make terrestrial and space-based radio emissions the same.
Satellites can disrupt astronomy in more ways than just transmitting radio signals. Time-lapse images can show white streaks caused by the shiny spacecraft reflecting light back toward the planet’s surface. The International Astronomical Union issued a warning in December 2022 that BlueWalker 3, the largest communication satellite in the world, is causing interference that could “severely hamper progress in our understanding of the cosmos.”
