Space Force finds a dead Cold War-era satellite that was missing for 25 years

A tiny experimental satellite has been reclaimed by the US Space Force following its 25-year disappearance. Luckily, they might be able to monitor it this time.

Upon arrival, the S73-7, also known as the Infra-Red Calibration Balloon (IRCB), proved to be a failure. Launched in 1974 from the KH-9 Hexagon, one of the largest Cold War spy satellites operated by the Air Force, it successfully ejected but did not fully inflate. The 26-inch balloon’s intended use, which was to assist ground equipment in calibrating remote sensing instruments, was rendered impossible by this malfunction. It turned into just one more space debris object.

The IRCB was soon lost from view, only to be found again in the early 1990s. Then it was gone once more. Now, another 25 years later, the 18th Space Defense Squadron of the Space Force has succeeded in moving the now-defunct apparatus.

Jonathan McDowell @planet4589 posted on X/Twitter, writing “The S73-7 satellite has been rediscovered after being untracked for 25 years. New TLEs for object 7244 started appearing on Apr 25. Congrats to whichever @18thSDS analyst made the identification.”

The S73-7 satellite has been rediscovered after being untracked for 25 years. New TLEs for object 7244 started appearing on Apr 25. Congrats to whichever @18thSDS analyst made the identification. pic.twitter.com/YJOow5o4ND

— Jonathan McDowell (@planet4589) April 29, 2024

Then how does a satellite disappear and then resurface twice? It’s actually very easy. There are currently over 27,000 objects in orbit around Earth, most of them spent rocket boosters, and neither they nor the different satellites have any sort of identifying beacon. Tracking systems identify objects by comparing their path with that of a known satellite.

When you have a small number of competitors in a similar orbit and recent radar data, pinpointing satellites is typically simple. But in crowded spaces, things become more challenging, particularly when the target is a tiny calibration balloon that is decades old.

It’s unclear exactly what tip-off the Space Force received to recognize the recently discovered object as the S73-7. Still, this rediscovery makes further tracking possible. The balloon’s altitude has only decreased by roughly 9 miles from its initial 500-mile position, based on McDowell’s data. Before gravity drags it down to burn up in the atmosphere, it probably won’t be long.

It may seem insignificant to keep an extensive list of orbiting objects, but doing so is essential for both space exploration and our increasing reliance on satellite networks.