Astronomy & Astrophysics published a research paper recently that looked at “Unintended Electromagnetic Radiation from Starlink Satellites”. The study was done in conjunction with the Low Frequency Array (LOFAR) telescope in the Netherlands.

The LOFAR telescope is a network of over forty radio antennas spread across the Netherlands, Germany, and the rest of Europe. This array can detect extremely long radio waves from objects in space. The antennas are located purposefully in remote locations to reduce interference from other radio sources.

The study documents that about fifty of the 4,000 current Starlink satellites are emitting frequencies in the range between 150.05 and 153 MHz, which have been set aside worldwide for radio astronomy by the International Telecommunications Union. The emitted radiation from the satellites is not intentional, and the guess is that these are stray frequencies being generated by components of some of the electronics. This is a common phenomenon for electronics of all sorts, but in this case, the stray frequencies are interfering with the LOFAR network.

This interference adds to the larger ongoing concern about the unintended impact of large satellite constellations on various branches of science. We already can see that satellites mar photographs of deep space as they pass in front of cameras. The intended radiation from the satellite constellations can accumulate and interfere with other kinds of radio telescopes. There is a fear that this current radiation will interfere with the Square Kilometer Array Observatory that is being built in Australia and South Africa. This new project is being built in remote locations away from cellphones, terrestrial TV signals, and other radios. But satellite arrays will still pass within the range of these highly sensitive radio sites.

The fear of scientists is that interference will grow as the number of satellites increases. Starlink’s current plans are to grow from the current 4,000 satellites to over 12,000 satellites – and the company has approval from the FCC to launch up to 30,000 satellites. There are numerous other satellite companies around the world with plans for constellations – and space is going to get very busy over the next decade.

One of the issues that concern scientists is that there is nowhere to go for relief from these kinds of issues. There are agreements reached at the International Telecommunications Union for setting aside various bands of spectrum for scientific research. But there is no international policemen with the authority to force satellite companies into compliance.

In this case, Starlink is working with the scientists to identify and isolate the issue to hopefully eliminate the stray radiation from future satellites. If the problem gets too bad, the FCC could intercede with Starlink. But who would intercede with satellites launched by governments that don’t care about these issues?

I don’t know how many of you are stargazers. When I was a kid in the early 60s, it was a big deal to see a satellite crossing the sky. A few satellites, like Telstar, were large bright objects crossing the sky. Most of the new satellites are much smaller, but it still doesn’t take very long watching the sky to see a satellite crossing. The sky is going to be busy when there are tens of thousands of satellites passing overhead. It’s hard to think that won’t have unexpected consequences.