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

After a 25-year disappearance, the US Space Force has reacquired a minuscule experimental satellite. Thankfully, this time they might be able to keep tabs on it.

The S73-7, nicknamed the Infra-Red Calibration Balloon (IRCB), was a dud upon arrival. Launched in 1974 from one of the Air Force’s biggest Cold War spy satellites, the KH-9 Hexagon, it ejected successfully but failed to inflate fully. This malfunction rendered the 26-inch diameter balloon useless for its intended purpose – aiding ground equipment in calibrating remote sensing instruments. It became just another piece of space debris.

Observers quickly lost sight of the IRCB, only to rediscover it in the early 1990s. Then, it vanished again. Now, after another quarter-century, the Space Force’s 18th Space Defense Squadron has managed to relocate the defunct device.

Jonathan McDowell (@planet4589) wrote on X/Twitter that, “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

So, how does a satellite vanish and reappear twice? It’s surprisingly simple. With over 27,000 objects, mostly spent rocket boosters, currently circling Earth, these spacefaring objects, along with various satellites, lack identification beacons. Tracking systems rely on matching a detected object’s path with a known satellite’s orbit for identification.

Pinpointing satellites is usually straightforward when you have recent radar data and a limited number of contenders in a similar orbit. However, things get trickier in crowded areas, especially when the target is a decades-old, miniature calibration balloon.

The exact tip-off that led the Space Force to identify the newly detected object as the S73-7 remains unclear. Regardless, this rediscovery allows for continued tracking. According to McDowell’s data, the balloon’s altitude has only dropped about 9 miles from its original 500-mile position. It’ll likely be a while before gravity pulls it down to burn up in the atmosphere.

Maintaining a detailed inventory of orbiting objects might seem unimportant, but it’s crucial for our growing reliance on satellite networks and the future of space exploration.