Updated: Nov 29, 2021
Is there a mysterious alien craft orbiting the Earth, a craft that’s kept watch over our development for the past 13,000 years? Did Nikola Tesla detect its strange repeating signals in 1899? What role did European physicists play in recording evidence of this enigmatic object in the 1920s? Here is the convoluted story of the Black Knight satellite…
If you search the internet for the “Black Knight satellite” you'll find a mass of really weird and wonderful claims, assertions, beliefs, photos and videos. But where did this is ominous name come from? Well it seems the origin of is part of the enigma, and with such a charismatic title it’s no wonder the narrative has run and run, although it appears this object was unnamed prior to 1998.
A British rocket called the Black Knight was used in conjunction with the Blue Streak missile warhead development programme between 1958 and 1965, to test re-entry vehicles. A “Black Knight satellite launcher” project announced in 1964 was considered a priority by the British Ministry of Aviation. The programme never put anything into orbit, and it is unrelated to the Black Knight satellite legend. 
What is now known as the Black Knight satellite has been spotted, tracked, lost, found again and destroyed – or not – in this fascinating mix of conspiracy, weird science, alien civilizations and astronomy.
I first heard of this object in 1974 when my physics teacher brought in a copy of either Analog or Spaceflight magazine. It contained an article “Space Probe from Epsilon Boötis” written by Duncan Lunan. In it he described a theory suggested by Professor Bracewell in 1960 that an efficient means of initiating contact between intelligent civilisations would be to send out unmanned messenger probes to the stars likely to have planets where intelligent life might evolve. 
Such a probe would orbit in the destination system, "listening" for artificial radio signals; the most effective test for discovering intelligence would be to "echo" back any signals it received from the target planet. If an intelligent response came from the planet, the probe would begin an information exchange, leading eventually to direct radio contact between the two civilizations at a high level of understanding. "Should we be surprised," wrote Bracewell, "if the beginning of its message were a TV image of a constellation [of the probe’s origin]?" Is that exactly what was accidentally discovered nearly 100 years ago?
In the 1920s research into how radio waves propagate around the world was in full swing. Reliable and powerful radio transmitters started connecting nations and continents via wireless telegraph, telephone and news/entertainment radio stations. It was important to fully understand what influenced the reliability of these transmissions. To this end, the Philip’s station PCJJ in Eindhoven, Holland, was transmitting experimental pulses. When conditions are just right a radio signal can propagate or echo right around the world. This takes about 1/7th of a second, any subsequent circumnavigations being too weak to be detected.
However, during these experiments, occasional echoes of between three and 15 and even 30 seconds were measured by engineer Jørgen Hals in Oslo, Finland, about 600 miles away from the PCJJ Eindhoven transmitter. These astonishing echoes (later to become known as long delayed echoes or LDEs) were almost as strong as the originating direct pulses. Physicist Balthasar van der Pol helped Hals and Professor Carl Størmer investigate the echoes, but due to their erratic quality and variations in time-delay, they did not find a suitable explanation. They eventually assumed some natural cause, possibly ionised gas or plasma out in space. Nevertheless they noted the timings of the echoes and this data was published in Nature, December 1928. This research was located and analysed by Duncan Lunan in 1972. 
Lunan replotted these pulses on an X-Y graph and concluded they formed a star map of the Boötis constellation, with the star Epsilon Boötis in the position it would have appeared from Earth 13,000 years ago. He decided an alien probe must be responsible for storing then returning the PCJJ pulses, inserting the calculated delays thus confirming Bracewells’s prediction that initial images from such a probe might be a map of its origin. And thus the Black Knight story was born.  Unfortunately this important aspect of the narrative was spoilt once Lunan bravely withdrew his original Epsilon Boötis theory in 1976 when he located more accurate data from the 1920s experiments. This lead to him reassess his interpretation where he ruled out most of the star map translations. However, in 1998 he re-interpreted part of them. In subsequent years his retraction has been almost universally ignored. Lunan has also distanced himself from the Black Knight theory, although he never coined the phase in the first place. 
Step forward Mr Tesla
Like all good last-century scientific mysteries, Nikola Tesla puts in an appearance in this one too. He wrote in 1900 that in the in the previous year he heard repeating signals in his laboratory at Pikes Peak: “Notable changes occurred at a fixed time and the analogy among the changes and numbers was so clear, that I could not provide any plausible explanation. […] Only after a while it came to me, that the observed interference may occur as the result of conscious activities. […] People! We got the message from an unknown and distant planet. And it sounded: one... two... three.”
It is widely reported that what Tesla heard might have been a pulsar, although this is unlikely as they were only officially detected in 1968 using complex and sensitive equipment of a type Tesla couldn't have imagined. I suspect what he heard were “whistlers” caused by lightning which were both puzzling and annoying to early telephone engineers! However, despite what has been published, this is a retrospectively connected reference to Tesla, who never mentioned a satellite, although later he suggested the signals he detected may have come from Mars. These are three recordings of the sounds he might have thought came from outer space:
The Black Knight satellite made the odd appearance in the past few decades. In 1954 UFO researcher Donald Keyhoe told various US newspapers the US Air Force had announced that two satellites were found to be orbiting the Earth, at a time when no nation yet had the ability to launch them. Sceptics have noted that Keyhoe had been promoting his UFO book at the time, and the news stories were not intended to be taken seriously. 
In 1957 there was a widely circulated story that a mysterious, unknown satellite was detected in polar orbit “shadowing” the first artificial satellite, the Soviet Sputnik 1. This is an odd claim since Sputnik 1 was not in a polar orbit. The technology for such orbits was not possible until 1960. 
Then in February 1960 Time magazine reported that the U.S. Navy had detected a dark object tumbling in a highly eccentric orbit. A follow-up article from the US Department of Defense confirmed that the object was “the remains of an Air Force Discoverer VIII satellite that had gone astray.” This was a spy satellite, the details of which were kept deliberately vague. 
No high-profile UFO story is complete without the claimed involvement of some senior military
official to lend credibility. In the case of the Black Knight, US Air Force pilot and Project Mercury astronaut Gordon Cooper is our man. Cooper announced seeing many UFOs throughout his career. So when it was claimed that he saw green lights belonging to the Black Knight during his 1963 Mercury 9 mission into Earth orbit (with ground control radar also allegedly picking up something inexplicable) it is often believed to be true. This is despite some versions of the story having NASA brush this off as a hallucination caused by a minor malfunction of his breathing apparatus. However Cooper produced transcripts of his mission showing that during that Mercury flight he reported nothing unusual and neither was there evidence of the inexplicable radar-tracked object. 
A Black Knight photo at last
The Black Knight narrative received a massive uplift in 1998 when NASA photos emerged (or were "leaked" according to the Conspirasphere) of a large, dark object in low Earth orbit. They were taken during STS-88, which was the first Endeavour Space Shuttle mission to the International Space Station (ISS). Clear photographic proof at last; exactly what everyone was waiting for.
A quick internet search will reveal that the object was a trunnion pin cover accidentally released during extravehicular activity while the ISS was being constructed. Once captured on camera, NASA gave this black form the Object Number 025570, and a few days later it fell from orbit and burned up. Far from being an extra-terrestrial object, the black item floating in space was nothing more than a type of protective blanket. The name "Black Knight" appeared around the time these photographs were released. 
Targeted by the Illuminati
Surely this whole story is already sufficiently bizarre? But no, there’s more! Apparently the enigmatic Black Knight was shot down on 16 March 2017 by a “secret Illuminati war plane” using an “anti-matter war head”, according to those behind the YouTube channel SecureTeam10 and then picked up by various British tabloids. There’s an unconvincing video, also apparently showing what are claimed to be alien escape pods, which is strange since despite all the weird claims surrounding the object, it having contained aliens was never one of them! 
Notwithstanding the SecureTeam10 video, perhaps the Illuminati missed, or at least shot something else down in error. In November 2020 a report was published in the British tabloid the Daily Express, stating the Black Knight was seen over the Philippines. A video claiming to have been made over Santa Rosa, south of Manila, was later analysed by Taiwan-based conspiracy theorist Scott C Waring. He says: "This is 100 percent alien, no doubt about it", and concluded that the UFO might be the Black Knight satellite. However, the video shows what could be interpreted as partly deflated helium balloon – drifting about under low cloud above some trees. Hardly the behaviour of a satellite. 
The genuine bit
It’s sometimes reported that these long delayed echoes are no longer observed. But that’s not the case. They are still occasionally reported by radio users, particularly radio amateurs, but the radio bands are now very congested, so if or when these echoes occur they are simply not noticed. Occasional recordings are made, and there has been much academic research into the causes of LDEs, but still no firm theory. However, there are about five possible explanations currently under consideration, (none of them requiring an alien probe) and the most likely involve reflections from the Earth’s magnetosphere and/or clouds of plasma near the Earth or Moon. This was suggested by at least one of the original experimenters in the 1920s. Despite the research LDEs were always considered a fringe subject - rather like ball lightning - due to their lack of repeatability and unpredictable behaviour, yet continue to be occasionally reported. Nevertheless, at last the phenomenon is being taken seriously by science, albeit a bit late in the day. 
While researching the Black Knight theme I found numerous questionable or unsourced internet “factoids” which I have omitted, so if anyone thinks some detail or other is missing, that’s probably why. In general the whole epic turned out to be another example of stories being retold without referring to original sources; where misunderstanding and misquoting get repeated, all cobbled together by lazy writers, thus becoming part of the established narrative. The more I dug the less there was.
I think the Black Knight satellite legend is perfectly assessed by the senior education support officer Martina Redpath of Armagh Planetarium in Northern Ireland: “The 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.” That just about sums it up!