1951 · Cooper: undated "two days" in 1951, over Europe (West Germany per later accounts)
Gordon Cooper and Deke Slayton: two future astronauts' 1951 sightings
WhenSlayton: 12 December 1951, 15:50 CST, about 5 mi SE of Hastings, Minnesota
WhereCooper: undated "two days" in 1951, over Europe (West Germany per later accounts)
Backing1 independent
Witnesses1 named
war.gov video · file page ↗
In their own words
“I also had occasion in 1951 to have two days of observation of many flights of them of different sizes flying in fighter formation generally from east to west over Europe. They were at a higher altitude than we could reach with our jet fighters of that time.”
Gordon Cooper, former USAF fighter pilot and Mercury astronaut, letter read at the UN, 27 Nov 1978 · source
Two of the Mercury Seven reported UFOs from their pre-NASA fighter years. Deke Slayton's sighting is on the record. It is in a contemporaneous Air Intelligence Information Report from his own wing, 133rd FIW Report 3-51 of 19 Dec 1951. Flying an F-51 on a test flight, he chased a small white object that resolved into two overlapping counter-rotating discs, outpaced him in a turn, and vanished. Blue Book's status reports first listed it with "no conclusions". The later record card reads "Was Balloon", without any documented balloon match. Gordon Cooper's 1951 sighting rests on his own later statement, a letter of 9 Nov 1978 that was read into the UN General Assembly's Special Political Committee record. In it he says he had "two days of observation of many flights of them ... flying in fighter formation, generally from east to west over Europe", above the reach of his jet fighters. No contemporaneous document of Cooper's sighting has been found.
Evidence, in date order (1)
- 1951General Mills balloon research team (per wing intelligence officers)witnesssaw the same or a similar object near a large balloon launch (secondhand, via Slayton's Deke!) NICAP case directory, Hastings 12 Dec 1951 (Sparks summary)
How plausible · High
A contemporaneous wing intelligence report records Slayton's chase; the balloon label has no balloon track in the file, and Cooper's sightings rest on his own word.
- ●●Access He flew the chase.
- ●●No gain sought Nothing to gain.
- ●●Character record Mercury astronauts.
- ●●Checkable details check out Wing intelligence report.
- ●○Cost of speaking Future astronauts, named.
- ●○Consistent over time Retold in memoirs.
Plausibility weighs how well an account fits where secrecy hides the documents by design, so missing records never count against it. Strength measures what is documented. Assessed 2026-10-23.
On the record
- "At 2150Z on 12 December 1951, Capt. Donald K. Slayton, observed an unidentified object five (5) miles southeast of Hastings, Minnesota." He was "cruising at 10,000', and had just pulled out of a loop and was heading back towards Wold-Chamberlain Airfield, when he first spotted a white object about one (1) mile out and 1,000' below his left wing tip". The flight was a test flight in an F-51; he was with the 133rd Maintenance Squadron, 133rd Fighter-Interceptor Wing.
- It "appeared to resemble a kite". Then it was "round white object ... the pilot assumed the object was a weather wind balloon riding down-wind. It appeared perfectly round, 18" to 2' in diameter, white or silver. The object gave an illusion of spinning, which at this stage was attributed by Capt. Slayton, to light diffusion."
- He made a left 180° turn to intercept. "The object began to turn to the left and seemed to gain speed rapidly ... It was at this point the pilot became aware the object was not floating in space, but rather had accelerating and maneuvering abilities."
- At an assumed 500 yards, "the object appeared to be two disks 18" to 2' in diameter and approximately 1' apart, spinning at a rapid rate". Then "the object or objects gained speed ... at a very rapid rate, and took on the appearance of a single object". "Rotational effect appeared to be in a counter-clockwise direction at all times."
- Slayton's speed was about 280 mph. "The pilot assumes the speed of the object at this point was about 380 or 400 mph." He "lost sight of object" when he went back into the turn.
- "Visibility on this day was exceptionally good ... Due to the fact that the aircraft was at 10,000', no correct estimation of distance was obtained." Status Report No. 2: "White object resembling a kite about 1000 ft. below a/c"; 3-4 min; sound none; speed 380-400 mph; "Action or comments: Pending". Status Report No. 3, p. 5: the same entry, with "Action or Comments: No conclusions". The same table lists two Minneapolis reports from 10 and 11 October 1951 of a "round, silver object seen by pilots tracking a balloon", sourced "Balloon Obs.", also with "no conclusions". Record card: final evaluation "Was Balloon" / "Evaluated as balloon". There is no balloon release, track or analysis in the pages I read. Cooper, letter read at the UN, 27 Nov 1978 (firsthand written statement, read by a delegate):
Claims
Slayton's own later account in *Deke!* (1994): "I realized I wasn't closing on that son of a bitch (firsthand (Slayton memoir), quoted by *Mpls.St.Paul Magazine* (mspmag.com). Not checked against the book.)firsthandSourced, unconfirmed
After the intercept, wing intelligence officers told Slayton that a balloon research team (General Mills) had seen the same or a similar object near a large balloon launch (secondhand. The chain: unnamed intelligence officers to Slayton to *Deke!*, as summarised by Brad Sparks (NICAP). It fits the October 1951 Minneapolis "balloon observers" entries in Status Report 3.)secondhandSourced, unconfirmed
In 1980 Slayton estimated the object's angular size as a grapefruit at arm's length (about 11°). Sparks calculates that the size and distance data in the report imply about 0.1° (analysis (Sparks). The 1980 interview (interviewer not named on NICAP; Wendy Connors supplied the case) has not been seen.)analysisSourced, unconfirmed
Brad Sparks lists the Slayton case as "BBU", meaning Blue Book Unknown, in his catalogue (case 496) (analysis. This conflicts with the record card's "Was Balloon". Sparks may be counting the Status Report 3 "no conclusions" listing. I have not checked this.)analysisSourced, unconfirmed
Cooper's 1951 observations took place while he flew F-86 Sabres in West Germany. His later memoir *Leap of Faith* (2000, with Bruce Henderson) is said to give fuller detail, including the base and the objects' appearance (firsthand claim, late (about 49 years after). I have not read the memoir, so its details (aircraft type, base, description) are not given here and the F-86/West Germany setting above is unverified.)firsthandSourced, unconfirmed
Cooper also said in the letter that "there was only one sighting from space of what may have been a UFO (firsthand opinion. The sighting is unspecified.)firsthandSourced, unconfirmed
Where
Cooper: undated "two days" in 1951, over Europe (West Germany per later accounts)
50.5°N 9.0°E · region only
war.gov files on this case (1)
AudioInterview Excerpt with Astronaut Gordon Cooper, 1962NASA · Release 03 · November, 1962
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Sources
- UAP Discovery forum post reproducing the Blue Book record card, AIIR 3-51 and Status Reports 2-3 (images)
- NICAP case directory, Hastings 12 Dec 1951 (Sparks summary with microfilm refs)
- UN document A/SPC/33/PV.36 (27 Nov 1978), Cooper letter read by Grenada
- NASA-UAP-D023, Cronkite interview with Cooper, 1962 (source: war.gov PURSUE; mirror, not listened to)
- *Mpls.St.Paul Magazine*, "Close Encounters of the Minnesota Kind" (quotes *Deke!*)