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The Black Knight Satellite

Is a mysterious 13,000-year-old alien satellite orbiting the Earth?  

by Brian Dunning

Filed under Aliens & UFOs, Urban Legends

Skeptoid Podcast #365
June 4, 2013
Podcast transcript | Download | Subscribe
Also available in Russian



STS-88 debris
Thermal blanket debris photographed from Endeavor, STS-88.
Image courtesy of the Image Science & Analysis Laboratory, NASA Johnson Space Center

Stories say it's up there in the blackness right now, just outside the Earth's glow. It tumbles slowly and deliberately through the darkness, sweeping smoothly along its unrelenting orbit. The Earth spins below, largely unaware of its unauthorized parasitic visitor. It is the Black Knight satellite, a mysterious object cirling the Earth, of unknown (and possibly alien) origin — the story says it's up there right now, and has been for 13,000 years.

Like so many stories of weird phenomena, the Black Knight satellite legend starts with Nicola Tesla. It's said that he picked up a repeating radio signal in 1899, that he believed was coming from space, and said so publicly at a conference. In the 1920s, amateur HAM radio operators were able to receive this same signal. Next, scientists in Oslo, Norway experimenting with short wave transmissions into space in 1928, began picking up Long Delay Echoes (LDEs), a not fully understood phenomenon in which they received echoes several seconds after transmission. The apparent explanation finally came in 1954 when newspapers (including the St. Louis Post Dispatch and the San Francisco Examiner) reported an announcement from the US Air Force that two satellites were found to be orbiting the Earth, at a time when no nation yet had the ability to launch them. It appeared that Black Knight had been detected by multiple lines of evidence, and was confirmed by the US Air Force.

By 1960, both the United States and the Soviet Union had hardware in orbit. But on February 11, 1960, newspapers everywhere reported some alarming news: that somebody else also had something in orbit. A radar screen, designed by the US Navy to detect enemy spy satellites, had picked something up. It was described as a dark, tumbling object. It wasn't ours, and it wasn't the Soviets' either.

The next day, newspapers reported a bit more information. The mysterious object was orbiting at about 79 degrees off from the equator, not the 90 degrees of a proper polar orbit. Its orbit was also highly eccentric, with an apogee of 1,728 km but a perigee of only 216 km. The object made a complete orbit every 104.5 minutes.

At the time, the Navy was tracking one known casing from an old Discoverer launch, a half shell a bit less than 6 meters long. Discoverer VIII had launched on November 20, 1959, a stepping stone toward launching a man into space and then recovering him in a parachuting capsule. The launch went as planned, but its mission to eject its 136 kg capsule didn't go so well. The capsule's casings came off as planned, but the capsule itself went astray into an orbit somewhat similar to that of the mystery object, and was eventually declared lost. The Navy tracked one of the casings, which was then orbiting every 103 minutes at 80 degrees, with an apogee of 950 km and a perigee of 187 km. Black Knight's object was similar, but not exactly the same.

And then, in 1963, astronaut Gordon Cooper reported seeing a greenish UFO during his 15th orbit on board Mercury 9. It was witnessed on the radar screens by approximately 100 people at NASA's Muchea Tracking Station near Perth, Australia. An official explanation given later was that Cooper's electronics malfunctioned, and he breathed in too much CO2 which gave him hallucinations. Black Knight's reality seemed to be undeniable.

In 1973, Scottish researcher Duncan Lunan wanted to know for certain. He went back to the Norwegian scientists' LDE data and analyzed it. Lunan discovered that it was a star chart pointing the way to Epsilon Boötis, a double star in the constellation of Boötes. Whatever Black Knight was, it appeared to be transmitting an invitation from the people of Epsilon Boötis, an invitation that was 12,600 years old, according to Lunan's analysis.

The final piece of proof came in 1998, when the space shuttle Endeavor made its first flight to the International Space Station on flight STS-88. Astronauts aboard Endeavor took many photographs of a strange object, which were widely available to the public on the NASA website. But soon the photographs all disappeared. They reappeared some time later, with new URLs, and with various descriptions explaining them all away as pieces of debris or space junk. The photographs were of high quality and unmistakably showed some type of craft. Since then we've known just about all there is to know about Black Knight. We know what it looks like, where it came from, when it came, its purpose as an ambassador, and it's been endorsed by so many reliable witnesses in the space program.

So then, why does nobody know about it; and why does NASA fail to acknowledge its existence?

What a great story. The idea of a 13,000-year-old alien satellite orbiting the Earth is about as exciting as it can get. People often accuse me of debunking stories like this, but I don't see it that way at all. I simply want to know more. I want to open the box wider and learn what's really going on. I don't want to stop here and say "That sounds weird"; I want to learn the solution to the mystery. To those of you who dismiss this as debunking, I really have to say I don't understand why learning the whole story is seen as a negative process. I'm excited by it, and I was excited to learn what's behind the Black Knight satellite. Here's what I found.

It turns out that all the bits of history making up the story of Black Knight are unrelated. The phrase "black knight" is so common that I was unable to determine when that name first became a part of the story. It seems improbable that the name would have come from any spacefaring nations at the time, as it's such a common name and has probably been assigned to any number of real projects. From 1958 through 1965, the United Kingdom launched 22 rockets in a program named Black Knight, intended to test various re-entry vehicles. But Black Knight never put anything into orbit; indeed, its second stage fired on the way down, not the way up, to better stress the re-entry vehicle. Take that name out of the equation, and all the links of the chain fall apart. All the events said to be connected to the Black Knight satellite were well documented on their own, and none (at the time) made any mention of such a name.

Nicola Tesla did indeed pick up rhythmic radio signals in 1899, and he did believe they came from space. Today we believe he was correct, and that what he picked up were pulsars, giant deep space sources of pulsing radio signals that were formally discovered in 1968. As pulsars were unknown in Tesla's day, he did his best to explain what he thought they might be: intelligent but undeciphered signals.

The Norwegian scientists did indeed receive LDE radio reflections, and their cause remains nearly as much a mystery today as it did then. Today we have five probable explanations, any or all of which may be responsible for some LDEs, and they mostly pertain to strange effects in the Earth's ionosphere. They are among about 15 plausible explanations. None of these includes orbiting alien satellites; although if an alien satellite elected to enter our orbit, record our transmissions, and transmit them back to us 8 seconds later, it could well have the same effect.

When Duncan Lunan did his translation of the LDE data in 1973 and came up with the star map, he never had any thought of Black Knight or any other strange polar satellite. In fact his interpretation was that the LDEs were coming from the Earth's L5 Lagrangian point. L4 and L5 are two points along the moon's orbit, one 60° ahead of it and the other 60° behind, which are stable and where gravimetric effects from the Earth and Moon will hold an object in steady orbit. Moreover, Lunan later acknowledged that his method was not only unscientific but that he'd made outright errors, and retracted it. So despite today's pop-culture story, there never has been any reasonable interpretation of anything connecting Epsilon Boötis to either a mysterious satellite or to a date of 12,600 years ago.

Those 1954 newspaper reports of two satellites in orbit? It was merely tongue-in-cheek reporting of the wild claims of a UFO crank trying to sell a book. The Air Force officer cited was merely a guy who had seen a UFO once, but in no way corroborated the idea of unknown satellites orbiting Earth. Nothing to do with the alleged Black Knight.

The most interesting part of the story was in 1960, when the Discoverer satellites were being launched. Secretary of the Air Force Dudley Sharp told newspapers that this new mystery object was probably the second casing from Discoverer VIII, the twin of the known piece they were already tracking, as it was the right size and in about the right place. This was soon confirmed. TIME magazine even reported the identification, but since a mundane explanation is not as exciting as a mystery object, it was back page news.

And there's another interesting footnote about the Discoverer program. In 1992, a Central Intelligence Agency program called Corona was declassified, and revealed that the Discoverer rockets were not about launching guys into space at all, but were actually carrying Corona spy satellites. The reason to use a polar orbit is that the craft eventually flies over every part of the Earth, and it's possible to photograph everything; unlike conventional semi-equatorial orbits that can only cover within a certain range of latitude. Back in those days there was no such thing as transmitting digital images back to Earth, so film cameras had to be used, and the film had to be dropped back to Earth to be developed and studied. The Corona KH-1 camera would de-orbit, pop a parachute, and then the parachute would be captured mid-air by a JC-130 recovery aircraft.

So although the entire Discoverer program was a front, the launches and results reported in newspapers at the time were indeed correct according to what was later declassified. The Corona camera aboard Discoverer VIII was indeed lost exactly as reported in the 1960 newspapers, and its casings and their eccentric orbit were also correctly reported.

So what was it that Gordon Cooper saw from Mercury 9, and that was corroborated by all those radar operators? According to Cooper himself (who died in 2004), what he saw was nothing at all. But make no mistake, Gordon Cooper reported seeing many UFOs during his flight career. He remains adamant about a fleet of UFOs that he says flew overhead while he was stationed in Germany, though nobody else there reports having known anything about it. But Cooper is also adamant that the Mercury 9 UFO — his supposed sighting of a greenish Black Knight in 1963 — is a complete fabrication by UFO authors that never happened. He offered all the transcripts, including his own originals, as proof that no such thing was reported during his flight. The story appears in virtually every UFO book about the Black Knight case, but there's no record of any such thing from NASA, from the radar station personnel, or from any contemporary source. It's purely an invention of modern writers.

So that leaves us with Endeavor's STS-88 flight, and their startling photographs of a spacecraft. There are a lot of things wrong with this part of the story. First of all, the shuttle always flew in a semi-equatorial orbit, as does the International Space Station. An object passing in a polar orbit would have gone by at tens of thousands of kilometers per hour, far too fast to be visible, and certainly far too fast for so many high-quality photos to be taken. During one of the astronauts' EVAs, a thermal blanket was lost and drifted away — silver on one side and black on the other. It was photographed extensively. It was crumpled and formed an odd shape. If you didn't know what to expect, the average person would have no clue what it was. But, unfortunately for the legend and fortunately for the astronauts, it simply wasn't an alien satellite.

I had a lot of fun learning more about this story. I learned a lot of history and some astronomical facts I didn't know. I'm glad I took the trouble, because if I had simply accepted the story that there's an alien satellite orbiting the Earth, I'd be wrong and I wouldn't have learned anything new. Worse, I'd have made a logical error, in being forced to accept a whole galaxy of wrong assumptions in order to shoehorn an improbable alien satellite into my reality. Neither legend nor mere debunking lead anywhere useful; it's only by tracking down the true facts that we earn the real rewards.

Correction: An earlier version of this incorrectly said that objects in perpendicular low Earth orbit would pass at "thousands of kilometers per second". In fact it's about 10 km/s, or about 36,000 km/h, if my math is right.

Correction: An earlier version of this said that the thermal blanket was discovered during the STS-88 initial visual inspection following launch, but it was actually lost and photographed during a subsequent EVA.

By Brian Dunning

Please contact us with any corrections or feedback.


Cite this article:
Dunning, B. "The Black Knight Satellite." Skeptoid Podcast. Skeptoid Media, 4 Jun 2013. Web. 21 Jan 2017. <>


References & Further Reading

Anonymous. "The Black Knight Satellite." The Living Moon. Blue Knight Productions, 1 Dec. 2008. Web. 24 May. 2013. <>

APS. "February 1968: The discovery of pulsars announced." This Quarter in Physics History. American Physical Society, 2 Jul. 2007. Web. 24 May. 2013. <>

Associated Press. "Dark Satellite Remains Mystery; Unclaimed by All." The Southeast Missourian. 11 Feb. 1960, Newspaper: 14.

Associated Press. "Air Force Ends Hunt for Missing Capsule of Discoverer VIII." Ocala Star-Banner. 23 Nov. 1959, Newspaper: 5.

Editors. "Radio Fence for Space Litter." New Scientist. 6 Apr. 1961, Number 229: 887.

Editors. "Science: Space Watch's First Catch." TIME Magazine. 7 Mar. 1960, Magazine.

Oberg, J. "In Search of Gordon Cooper's UFOs." James Oberg Articles. Peter Smith Web Design, 1 Jan. 1983. Web. 27 May. 2013. <>

Oberg, J. "Phantom Satellite?" Space Folklore. James Oberg, 21 Oct. 2014. Web. 20 Aug. 2015. <>

Van der Pol, B. "Short Wave Echoes and the Aurora Borealis." Nature. 8 Dec. 1928, Issue 122: 878-879.


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