Lost Satellite Rediscovered After 25 Years: Challenges in Tracking Space Debris

The rediscovery of the Infra-Red Calibration Balloon (S73-7) satellite, after drifting undetected in space for 25 years, highlights the challenges of tracking space debris. Launched in 1974 as part of the United States Air Force’s Space Test Program, S73-7 was meant to serve as a calibration target for remote sensing equipment. However, it failed to deploy as planned and disappeared from radar detection twice, in the 1970s and again in the 1990s, before its recent rediscovery.

Jonathan McDowell, an astrophysicist from the Harvard-Smithsonian Center for Astrophysics, explained that the difficulty in tracking such satellites lies in their low radar cross-section and the possibility that what’s being tracked might be a component that didn’t deploy correctly. With over 20,000 objects currently orbiting Earth, identifying and cataloging each one presents significant challenges, especially when considering the crowded parameter space and the need to match tracked objects with known satellites.

Engineers rely on ground-based radar and optical sensors to track space debris, but alterations to a satellite’s trajectory or incomplete maneuvering data can complicate the process of locating them. McDowell emphasized the importance of efforts to track and identify lost satellites and debris, especially as the number of objects in orbit continues to increase.

While missing one or two objects may not pose a significant risk, comprehensive tracking efforts are essential for ensuring the safety and sustainability of space activities.