Black Knight satellite

The Black Knight satellite is the name given to a supposedly anomalous extraterrestrial object in near-polar orbit of the Earth. According to some conspiracy theories, NASA is engaged in a cover-up regarding its existence and origin. This conspiracy theory combines several unrelated stories into one narrative.

A photo taken during the STS-88 mission claimed by some to show the Black Knight satellite is catalogued by NASA as a photo of space debris, and space journalist James Oberg considers it probable the debris is a thermal blanket confirmed as lost during the mission.

History
According to some UFO conspiracists, the Black Knight is an artificial satellite of extraterrestrial origin which has orbited Earth for approximately 13,000 years; the "satellite" story is most likely a conflation of several disconnected stories about various objects and their interpretations, all of them well documented independently and none using the term "Black Knight" upon their first publication. According to senior education support officer Martina Redpath of Armagh Planetarium in Northern Ireland:

"Black Knight is a jumble of completely unrelated stories; reports of unusual science observations, authors promoting fringe ideas, classified spy satellites and people over-interpreting photos. These ingredients have been chopped up, stirred together and stewed on the internet to one rambling and inconsistent dollop of myth."

The origin of the Black Knight legend is often retrospectively dated back to repeating extraterrestrial radio signals heard during the 1899 radio experiments of Nikola Tesla and long delayed echoes first heard by amateur radio operator Jørgen Hals in Oslo, Norway, in 1928. Brian Dunning of the Skeptoid podcast attributes Tesla's 1899 radio signals to pulsars, which were not identified until 1968.

In 1954, UFO researcher Donald Keyhoe told newspapers that the United States Air Force had reported that two satellites orbiting Earth had been detected. At that time, no country had the technology to launch a satellite. Skeptics have noted that Keyhoe had been promoting a UFO book at the time.

In February 1960, TIME reported that the U.S. Navy had detected a dark object thought to be a Soviet spy satellite in orbit. A follow-up article confirmed that the object was "the remains of an Air Force Discoverer VIII satellite that had gone astray."

In 1963, astronaut Gordon Cooper supposedly reported a UFO sighting during his 15th orbit in Mercury 9 that was confirmed by tracking stations, but there is no evidence that this happened. Neither NASA's mission transcripts nor Cooper's personal copies show any such report being made during the orbit.

In 1973, Scottish author Duncan Lunan analyzed the long delayed radio echoes received by Hals and others and speculated that they could possibly originate from a 13,000 year old alien probe located in an orbit around the Earth's Moon. He suggested that the probe may have originated from a planet located in the solar system of star Epsilon Boötis. Lunan later retracted his conclusions, saying that he had made "outright errors" and that his methods had been "unscientific".

Responses to photographs from the 1998 STS-88 mission originated the term "Black Knight" and kickstarted the theory. Space journalist James Oberg considers it probable that the photographs are of a thermal blanket that was confirmed as lost during an EVA by Jerry L. Ross and James H. Newman.