FCC Direct-to-Device Proposal Raises Radio Astronomy Interference Fears

The Federal Communications Commission published a proposal in early September that would allow billions of Internet of Things devices to send signals to satellites using the 2.4 and 5.8 gigahertz spectrum bands — frequencies that are also critical to radio astronomy. Scientists warn the flood of human-made radio emissions could drown out the extremely faint signals telescopes are built to detect.

Greg Hellbourg, spectrum manager at the Owens Valley Radio Observatory, said space launches are becoming easier and the FCC is increasingly adopting rules with "game changing" implications for astronomy. He noted that a 2024 FCC rule already allowed cell phones to communicate directly with satellites, effectively placing cell towers in the sky above even the most remote observatories. The current proposal could accelerate that trend, threatening NSF-funded facilities such as the Very Large Array and the Very Long Baseline Array, which both rely on those same bands.

Aaron Boley, an astronomy professor at the University of British Columbia, warned of a broader pattern of opening spectrum to new uses, saying radio astronomy could be "severely curtailed from Earth" if care is not taken. Hellbourg added that emissions from the more than 16,000 satellites now in orbit already exceed levels set by the International Telecommunications Union for protected radio astronomy bands, and satellite megaconstellations could eventually number in the millions.

The proposal also seeks input on space-to-Earth transmissions, which Hellbourg said pose an even greater risk because they can affect telescopes that are not pointed directly at the transmitting satellites. The comment period closes November 9.