Elon Musk’s Starlink (SpaceX) service, which operates a mega constellation of ultrafast broadband satellites in Low Earth Orbit (LEO) for the UK and the world, has issued a new update to explain how they dynamically adjust their network to mitigate the “significant risk” of causing interference for radio telescopes.
At present Starlink currently has 6,313 LEO satellites (c.2,000 are Mini GEN 2A) in Low Earth Orbit at altitudes of c.500-600km and they’re in the process of adding thousands more by the end of 2027. Customers in the UK typically pay from £75 a month for a 30-day term, plus £299 for hardware on the ‘Standard’ plan, which promises internet latency times of 25-60ms, downloads of c. 25-100Mbps and uploads of c. 5-10Mbps.
However, SpaceX’s engineers have recognised that direct transmissions from their satellites (as well as others) “towards the eye of radio telescopes” may pose a “significant risk of interference to astronomical research“, which is why they’ve spent the past few years working with the National Science Foundation (NSF) and the National Radio Astronomy Observatory (NRAO) to develop new techniques to “mitigate this risk“.
The goal being that everybody gets to enjoy streaming more cat videos, while simultaneously protecting and enabling critical radio astronomy sciences to continue their work unabated by the new mega constellation polluting the sky above their heads. But a new update from Starlink has shed a bit more light on how they’ve tackled this problem.
Starlink’s Statement on Radio Astronomy
Engineers from SpaceX and NRAO have determined, through years of collaborative experiments, that the direct transmissions from satellites towards the eye of radio telescopes may pose a significant risk of interference to astronomical research. To mitigate this risk, the teams from SpaceX and NRAO have developed techniques that enable Starlink satellites to avoid transmissions into the line-of-sight of radio telescopes by leveraging Starlink’s advanced phased array antenna technology, which can dynamically steer satellite beams away from telescopes in milliseconds.
These techniques are made possible by a real-time data sharing framework between radio astronomy observatories and Starlink that provides the Starlink network with a telescope’s planned observation schedule, including the telescope’s pointing direction (aka “boresight”) and its observed frequency band. With this information, the Starlink network can ensure that satellites passing near the boresight of a telescope dynamically redirect their beams away from the telescope.
This boresight avoidance method protects the telescope’s observations while ensuring Starlink service remains uninterrupted for customers near the telescope, and it is now live and operational for the Starlink network and NRAO’s Very Large Array in New Mexico.
The same approach has also been deployed for the Green Bank Observatory in the National Radio Quiet Zone in West Virginia (USA) and there’s even a research paper covering the results from that. Nevertheless, there are thousands of radio telescopes around the world and thus SpaceX intends to continue its work with the radio astronomy community, which aims to expand the implementation of this to “other observatories in the USA and beyond“. Quite how far they’ll get with this remains to be seen.
SpaceX added that it maintains an “open invitation to other radio astronomy organizations from around the world” to implement the approach to help protect their important scientific research. But Starlink isn’t the only company or country looking to build such a mega constellation in Low Earth Orbit and we can only hope that all the others are being mindful of this problem too.