Is the Black Knight satellite real? The 'alien probe', explained

What happened: how the Black Knight story was assembled

What is the Black Knight satellite? In the popular telling, it is an artificial object of alien origin in a near-polar orbit around Earth, watching humanity for some 13,000 years. Live Science points out that the evidence offered for it is so disparate that it is hard to see why the pieces are linked at all, and the Armagh Observatory and Planetarium calls the story a jumble of unrelated parts. In order, the parts are these.

• 1899: Nikola Tesla, working in his laboratory in Colorado Springs, recorded unusual signals and speculated that they came from another planet. He never said a satellite was involved.
• 1920s: Radio operators heard their transmissions come back seconds later. The Norwegian engineer Jørgen Hals is credited with first observing these long delayed echoes, which Størmer and van der Pol reported in Nature in 1928.
• Early 1950s: Newspapers reported the discovery of an unknown satellite. According to Armagh, the articles were summaries of a book by the UFO writer Donald Keyhoe.
• 1960: Ronald Bracewell of Stanford University suggested in Nature that an alien probe might already be in our solar system.
• 1960: American newspapers reported an unidentified object in polar orbit that neither superpower claimed. Armagh concludes it was almost certainly debris from the US Discoverer 8 mission.
• 1973: Duncan Lunan argued in Spaceflight magazine that the long delayed echoes might come from an alien probe, which he linked to the star Epsilon Boötis and placed near the Moon for about 13,000 years.
• 1998: Astronauts on the space shuttle Endeavour photographed a dark object in low orbit.

Only the name joins these pieces into the Black Knight satellite mystery.

The Black Knight satellite photos: the official explanation

The photographs come from STS-88, the first space shuttle mission to assemble the International Space Station, in December 1998. NASA's catalogue of astronaut photography lists the frames as STS088-724-66, -68 and -70, taken on 11 December 1998 between 20:17 and 20:19 GMT with a Hasselblad camera and a 250 mm lens, from an altitude of 214 nautical miles (396 km). The catalogue's feature field for all three reads “space debris”.

The mission record explains the debris. On 9 December astronauts Jerry Ross and James Newman spent part of a spacewalk fitting thermal covers over the trunnions, large metal posts that had held the Unity module in the shuttle's cargo bay during launch. One cover slipped free of its tether and drifted out of reach. CBS News correspondent William Harwood's mission log records the commander, Robert Cabana, radioing Ross that one of the thermal covers had got away from him. The lead flight director, Robert Castle, told reporters the lost blanket posed no major problem.

According to Live Science, the cover was given the tracking number 25570, and a few days later it fell from orbit and burned up. Ross has explained the photographs as showing one of the four trunnion pin covers the crew carried, and James Oberg, a former NASA engineer who knows Ross and the cosmonaut who took the pictures, Sergei Krikalev, has documented the same sequence.

What the astronauts and other witnesses said

Ross lost three items during the first two spacewalks: a socket fitting, the thermal blanket and an access panel cover. Asked what he would tell other spacewalkers, he said, “Don't do what I did!” He told an interviewer he had never lost an item on four earlier spacewalks and had no explanation for why the tethers let go. Gregory Harbaugh, the astronaut in charge of spacewalk planning, said NASA would examine the tether hardware and reinforce strict tether discipline in training.

Other witnesses cited for the Black Knight fare worse. A story that the astronaut Gordon Cooper saw its lights during his Mercury flight is contradicted, Armagh notes, by transcripts showing he reported nothing of the kind. Duncan Lunan, whose 1973 theory supplied the 13,000-year figure, still thinks the echoes may point to a probe, but in comments quoted by Live Science he said his work has nothing to do with the Black Knight.

Where scientists stand

On the radio claims, scientists see nothing that needs a satellite. The NASA Jet Propulsion Laboratory scientist Varoujan Gorjian, quoted by Live Science, explained that the first radio source beyond Earth, the centre of our galaxy, was found in the 1930s and that pulsars were not detected until the 1960s. If Tesla picked up a real signal rather than a fault in his equipment, Gorjian said, it most likely came from Earth.

Bracewell's paper is real science, but it is a proposal, not an observation. Writing in Nature on 28 May 1960, he argued that an advanced civilisation might send probes to nearby stars rather than beam signals across space. Such a probe could listen for our radio signals and repeat them back, so that they would look like echoes delayed by seconds or minutes, like those reported in 1928 and never explained. He wrote, “Such a probe may be here now, in our solar system,” and urged scientists to stay alert to unexpected signals. He did not claim to have found one. The long delayed echoes still lack a confirmed cause, but an unexplained radio effect is not an object in orbit.

On the photos, Oberg, who led the trajectory design team for the mission before leaving NASA, says everything about them, from why the blankets were needed to how one floated off, fits ordinary spaceflight operations. In comments quoted by Live Science, he called them among the weirdest-looking 70 mm frames the shuttle programme produced, and said a NASA website update that broke the original image links fed talk of a cover-up.

Common questions

Verdict

The Black Knight satellite explained: there is no 13,000-year-old alien probe in orbit. The name joins a radio curiosity from 1899, unexplained radio echoes from the 1920s, a speculative 1960 paper, a 1973 hypothesis its author keeps apart from the legend, and NASA photographs whose subject is on record: a thermal cover lost during a space station assembly spacewalk on 9 December 1998, photographed two days later and destroyed on re-entry soon after. Real or Legend files the Black Knight satellite as debunked.