STS-75 Tether Incident — NASA Shuttle Footage

On February 25, 1996, during the STS-75 mission, Space Shuttle Columbia was conducting the Tethered Satellite System experiment — deploying a conducting tether 12.8 miles into space to generate electrical power via electromagnetic induction. The tether broke. While Columbia's cameras were documenting the broken tether drifting in orbit, dozens of disc-shaped objects appeared in the frame, swarming around and through the tether's position. The objects display a characteristic disc shape with a visible notch or bite taken from one edge. Critically, several objects are observed passing behind the tether — which, at 12.8 miles long and at known distance from the camera, establishes a minimum size for the objects. Analysis indicates the objects would need to be tens of meters or more in diameter to appear at that apparent size while behind the tether. NASA's official explanation attributes the objects to ice particles or debris from the shuttle illuminated by Earth-albedo light. Critics of this explanation note that the objects move in directions inconsistent with debris drifting from the shuttle in that orbital orientation, that several objects execute apparent course changes, and that the systematic notch geometry is inconsistent with random ice particles. The footage remains in the public domain as official NASA mission video.