The STS-75 Tether Incident

February 22, 1996. Space Shuttle Columbia lifted off from Kennedy Space Center on mission STS-75. In its payload bay sat the Tethered Satellite System Reflight, a joint project of NASA and the Italian Space Agency. The satellite was to be reeled out on a tether, with a target of 20.7 kilometres.

February 25. Over 19 kilometres had been deployed, over a period of five hours. Then the tether broke. NASA's failure investigation found that "an electrical arc inside the deployer mechanism burned through the tether." The satellite drifted free and stayed in orbit for weeks. It was easily visible from the ground.

The famous images came days later. According to James Oberg, the camera found the loose tether about three days after the break. On a Low-Light-Level TV camera, fed live to the ground, the tether appears as a long, sunlit line against the stars. Around it, many luminous, roughly circular shapes drift across the frame. Several have a notch cut from one edge.

Those who studied the tape describe objects that "seemed to pulse with light." Some "appeared to pass behind the 12-mile tether." Others made "abrupt stops," with "objects reversing their course by 180 degrees." There is no sound. Only the slow, silent drift.

Aboard Columbia, Franklin Chang-Díaz described the lights to Mission Control. They were, he said, "a little bit of debris that kind of flies with us," lit by the sun. Claude Nicollier also spoke with the ground. One later account noted that the exchange showed "no surprise or excitement from meeting the unknown."

In Vancouver, someone was recording. Television editor Martyn Stubbs taped the live shuttle feeds from STS-48 in 1991 to STS-80 in 1996. That came to over 2500 hours of raw video. He is credited with finding the tether clip and circulating it.

David Sereda pushed further. If the objects really passed behind a tether 77 to 100 nautical miles away, he calculated, they had to be miles in diameter. He called the footage "absolute proof of intelligent extraterrestrial craft in earth's orbit." His project with Dan Aykroyd, Evidence: The Case for NASA UFOs, and the documentary The Secret NASA Transmissions: The Smoking Gun carried the clip further. In 2014, enhanced versions revived the debate.

NASA's answer was simpler. Ice particles and debris, lit by sunlight. Shuttle water dumps create clouds of ice crystals that drift near the orbiter. The plasma discharge that broke the tether also produced many pieces of floating debris. The camera had focus problems at far distances and a malfunctioning manual iris. Small bright particles near the lens blur into large discs.

Sceptics say the notch copies the notched shape of the camera's aperture. Recreations, including one on UFO Hunters, filmed out-of-focus particles in front of a mock tether and reproduced the illusion of objects passing behind it. Oberg stressed the timing. The clip was shot days after the break, not at the moment it happened. Critics add that miles-wide craft near a satellite visible from the ground would themselves have been seen from the ground.

Nobody claims the footage is faked. It is genuine NASA downlink video, and the dispute is only about what it shows. For believers, it is a swarm of giants in orbit. For sceptics, it is space "dandruff," the ice and insulation flakes of shuttle life. Three decades on, the argument still runs.