Parcae: A Trio of Spy Satellites

Did you ever hear of a satellite called Parcae (pronounced like park-eye)? If you haven’t, don’t feel bad—it was, after all, a top-secret project only revealed in July 2023. [Ivan Amato] not only heard about it, but also wrote a fascinating peek into the cloak-and-dagger world of cold-war spy satellites for this month’s IEEE Spectrum.

According to [Ivan], the satellite helped the United States to keep track of Russian submarines and was arguably the most capable orbiting spy platform ever. Or, at least, that we get to hear about.

Given that it was built in the 1970s, it was amazing that the satellite wasn’t very large. The craft itself seemed small compared to its solar panels. Even today, the satellite remains a bit of a mystery. While the NRO—the US spy satellite agency—did acknowledge its existence in 2023, there is very little official information about it, although, apparently, other curious people have unearthed data on Parcae over the years. According to the NRO, the satellites have not been in use since 2008.

The Parcae—named after the Romans’ three fates—worked in groups of three and launched in a “dispenser” that carried the trio of spaceships. They could listen to radio emissions from ships and use very accurate clocks to pinpoint their location based on the slight differences in the time each satellite heard the signal.

One of the system’s unique features was that thanks to a minicomputer, ship positions could be in users’ hands in minutes. That doesn’t sound so impressive today, but it was an amazing achievement for that time.

The article goes into more detail about how the individual satellites used a gravity boom for orientation and a lot of details about the designers. Of course, some of what Parcae could do is still secret for now, so there may be more to this story later.

Spy satellites can’t always hide from backyard telescopes. Spy satellites always have impressive technology and—presumably—big budgets.