Researchers using the Low Frequency Array (LOFAR) radio telescope in Europe have discovered the second generation of Starlink satellites emit higher levels of radio waves that could pose a serious risk to radio astronomy.
This issue of radio-wave emission is in addition to the sunlight that Starlink and other satellites reflect, which can be visible to the naked eye and leave light streaks on optical images.
In observations taken over the summer, Starlink’s V2-mini — an upgraded model of its internet-providing satellites — emits up to 32 times more unintended electromagnetic radiation (UEMR) than its predecessor. The LOFAR radio telescope, composed of several antennas across Europe and managed by the Netherlands Institute for Radio Astronomy (ASTRON), tracked satellites on July 19 over the course of two one-hour sessions. The results, published in the journal Astronomy & Astrophysicson Sept. 18, found that the objects emitted more powerful radio waves than the previous generation. The issue is exacerbated by the fact that V2-mini satellites operate at a lower orbit than previous Starlink satellites.
According to LOFAR lead researcher Cees Bassa in an ASTRON news release, these satellites are about 10 millions times brighter in radio waves than any faint objects LOFAR could locate. “This difference is similar to the faintest stars visible to the naked eye and the brightness of the full Moon. Since SpaceX is launching about 40 second-generation Starlink satellites every week, this problem is becoming increasingly worse.”
SpaceX began launching the V2-mini generation of satellites early last year as part of the company’s Starlink constellation, which offers high-speed internet access across the globe. The satellites incorporate new measures to reduce their reflectivity, helping to mitigate their impact on optical astronomy and naked-eye observations. In a release in 2023, the company highlighted its work with astronomers, saying it has “prioritized collaboration with astronomers and scientists to mitigate the impact of Starlink satellite streaks on their observations.” However, the new results show there is more work to be done to lower their impact on radio astronomy.
SpaceX did not respond to requests for comment.
SpaceX has also worked with the U.S. National Science Foundation and National Radio Astronomy Observatory (NRAO) to reduce their impact on the field, having signed a coordination agreement in 2019. In experiments conducted since 2021 at the Very Large Array in New Mexico, SpaceX and the NRAO have worked on methods to coordinate operations so that Starlink satellites can steer their transmission beams away from operating radio telescopes. However, the radio emission detected in this new study concerns electromagnetic radiation that leaks out from satellites unintentionally.
The LOFAR study stated that there are ways to keep these satellites from interfering with radio telescopes. These actions include raising awareness, advocating for radio quiet zones, and stricter industry regulations.
The study states that with this new information, there is hope that SpaceX and Starlink will work to mitigate UEMR and its impact on astronomy in the future.
