Green Fireballs: Los Alamos and Sandia Records (1948–1950) – PURSUE Files

From late 1948, scientists, security guards and pilots around the nuclear weapons sites of New Mexico reported brilliant green fireballs streaking silently across the sky. This page brings together 116 pages from the Armed Forces Special Weapons Project and the Air Force listing 209 sightings of “green orbs,” “discs” and “fireballs” near Sandia Base (Release 02); the transcript of a February 1949 conference at Los Alamos Scientific Laboratory where Manhattan Project veterans including Edward Teller debated the cause (Release 04); 1970s correspondence of Los Alamos physicist James Tuck about UFOs; and a 1986 invitation to a talk titled “Why Should a Scientist be Concerned about UFOs?” (Release 02).^[1]

The records

DOW-UAP-D017, UAP Reported at Sandia Base, 1948-1950

Open DOW-UAP-D017 (PDF) on war.gov →

This file contains 116 pages of documentation from the Armed Forces Special Weapons Program (AFSWP) – the direct, post-World War II successor to the Manhattan Project – and from the U.S. Air Force – relating to a series of sightings and investigations in Sandia, New Mexico, from 1948-1950. This file contains 209 sightings of “green orbs,” “discs,” and “fireballs” reported near the military base. Witnesses reported unidentified anomalous phenomena (UAP) maneuvering, flying out of sight, disappearing, or exploding. The documents also include the results of contemporary investigations into residual copper powder found in some areas where sightings were reported. A few of these investigations became the basis for Project Grudge, which collected reports of unidentified flying objects from various other military installations – also included in this collection.

— Official PURSUE description

DOE-UAP-D004, Los Alamos Conference on Aerial Phenomena, 1949

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This document is a transcript of a 1949 conference held at Los Alamos Scientific Laboratory (now Los Alamos National Laboratory), Los Alamos, New Mexico. Attendees included several eminent scientists and physicists, many of whom had contributed to the development of the first nuclear weapons during the Manhattan Project. The purpose of the conference was to discuss and gather hypotheses to account for the nature and origin of a phenomenon involving “green fireballs” that had been reported over a period of several months in the vicinity of the laboratory. The group did not come to a consensus on a likely attribution for the phenomenon, though a leading hypothesis was that the observations may have been related to meteors entering the atmosphere at a shallow angle and high altitude. Dr. Edward Teller suggested that if not a “material body,” an “electron phenomenon” might be the cause, while Dr. Lincoln LaPaz, an expert specializing in meteorics, expressed that “nothing like this, to [his] knowledge, has ever been observed in the case of meteorite drops.”

— Official PURSUE description

DOE-UAP-D002, James Tuck Correspondence, 1970s

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Personal correspondence to and from James Tuck, a Los Alamos National Laboratory-affiliated physicist, regarding his interest in unidentified anomalous phenomena circa 1970s.

— Official PURSUE description

DOE-UAP-D003, Pajarito Astronomers Invitation, 1986

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A letter to the members of the Pajarito Astronomers club regarding an upcoming meeting featuring a presentation from a Los Alamos National Laboratory-affiliated physicist, Dr. John Warren, titled “Why Should a Scientist be Concerned about UFOs?” The referenced event was not officially hosted by Los Alamos. The laboratory has no record of the subject matter discussed at the meeting.

— Official PURSUE description

Analysis

What the scientists thought. The Los Alamos group did not agree on a cause. The leading idea was meteors entering the atmosphere at a shallow angle and high altitude; Teller suggested an “electron phenomenon” if not a “material body.” The official description notes the group reached no consensus.^[1] University of New Mexico meteor expert Lincoln LaPaz, who saw one himself, argued they were too slow, too low, too flat and too silent for meteors and did not leave meteorites, which led to the Air Force’s 1950–51 Project Twinkle camera study. Twinkle recorded nothing conclusive.^[2]

Copper and secrecy. The Sandia file mentions tests of copper powder found where some sightings occurred; burning copper produces a green flame, which fueled speculation about artificial objects. Some of these investigations fed into Project Grudge.^[1] Today most researchers accept that bright green bolides, which are common and were seen more often near heavily watched sites, explain much of the wave, though the clustering near nuclear facilities is still debated.

New or previously released? Partly. The green-fireball wave appears in Blue Book records and in Ruppelt‘s 1956 book. The full conference transcript, the 116-page Sandia file, and the Tuck and Pajarito items appear to be newly published.

Released files

See also

• Green fireballs (1948–1951)
• Los Alamos National Laboratory
• Sandia
• Edward Teller
• James Tuck
• Project Grudge
• PURSUE Release 02 (May 22, 2026) overview
• PURSUE Release 04 (July 10, 2026) overview
• PURSUE

Further reading

• Edward J. Ruppelt (1956). The Report on Unidentified Flying Objects (Amazon)

References

1. ^ U.S. Department of War (2026). PURSUE Release 02 (May 22, 2026), Release 04 (July 10, 2026): DOW-UAP-D017, DOE-UAP-D004, DOE-UAP-D002, DOE-UAP-D003, with official descriptions. war.gov/ufo.
2. ^ Ruppelt, E. J. (1956). The Report on Unidentified Flying Objects, chapter on the green fireballs and Lincoln LaPaz.