About 170 Starshield satellites built by SpaceX for the US government’s National Reconnaissance Office (NRO) have been sending signals in the wrong direction, a satellite researcher found.
The SpaceX-built spy satellites are helping the NRO greatly expand its satellite surveillance capabilities, but the purpose of these signals is unknown. The signals are sent from space to Earth in a frequency band that’s allocated internationally for Earth-to-space and space-to-space transmissions.
There have been no public complaints of interference caused by the surprising Starshield emissions. But the researcher who found them says they highlight a troubling lack of transparency in how the US government manages the use of spectrum and a failure to coordinate spectrum usage with other countries.
Scott Tilley, an engineering technologist and amateur radio astronomer in British Columbia, discovered the signals in late September or early October while working on another project. He found them in various parts of the 2025–2110 MHz band, and from his location, he was able to confirm that 170 satellites were emitting the signals over Canada, the United States, and Mexico. Given the global nature of the Starshield constellation, the signals may be emitted over other countries as well.
“This particular band is allocated by the ITU [International Telecommunication Union], the United States, and Canada primarily as an uplink band to spacecraft on orbit—in other words, things in space, so satellite receivers will be listening on these frequencies,” Tilley told Ars. “If you’ve got a loud constellation of signals blasting away on the same frequencies, it has the potential to interfere with the reception of ground station signals being directed at satellites on orbit.”
In the US, users of the 2025–2110 MHz portion of the S-Band include NASA and the National Oceanic and Atmospheric Administration (NOAA), as well as nongovernmental users like TV news broadcasters that have vehicles equipped with satellites to broadcast from remote locations.