Sandia Base Green Fireballs (1948–1950)
Between November 1948 and May 1950, hundreds of 'green fireball' sightings were reported over Sandia Base, Kirtland AFB, Los Alamos, and other U.S. nuclear-weapons sites in New Mexico — investigated by Dr. Lincoln LaPaz under USAF Project SIGN and GRUDGE, now declassified in PURSUE Release 02 as DOC-141.
Between November 1948 and May 1950, the U.S. Air Force and the Armed Forces Special Weapons Project (AFSWP) tracked an extraordinary cluster of 'green fireball' sightings centered on the nuclear-handling complex of Sandia Base, Kirtland Air Force Base, Los Alamos National Laboratory, and the broader Albuquerque-Alamogordo corridor in New Mexico. The Office of Special Investigations 17th District tabulated more than 209 distinct sightings during this period. Dr. Lincoln LaPaz, the University of New Mexico's leading meteor specialist, was retained to determine whether the objects were natural meteoric phenomena — and concluded that they were not. His Fourth, Sixth, and Seventh Reports on the green-fireball phenomenon are part of the 116-page DOW-UAP-D017 declassification, released under PURSUE on 2026-05-22 as catalog entry DOC-141. The bundle documents the foundational U.S. government UFO investigation that preceded Project SIGN, GRUDGE, and Blue Book.
“Several sightings of green lights were made at Los Alamos. These usually occurred during the early part of the night, nine to eleven, and were usually in the Jemez Mountains.”
Dr. Lincoln LaPaz's investigation
Dr. Lincoln LaPaz directed the Institute of Meteoritics at the University of New Mexico and was the U.S. military's top consultant on meteoric phenomena. The Sandia bundle declassified under PURSUE Release 02 contains his Fourth Report (December 20, 1948), Sixth Report, and Seventh Report (May 23, 1950). LaPaz personally observed green fireballs on multiple occasions and concluded they were not natural meteors — the flight characteristics (predominantly horizontal trajectories at low altitude, anomalous color, and lack of meteoritic debris recovery) ruled out the meteor hypothesis. His investigation triggered the AFSWP and USAF Project SIGN to treat the cluster as a national-security matter.
The OSI 17th District tabulated sightings
Pages 21–60 of DOC-141 contain the Office of Special Investigations 17th District's 'Summary of Sightings of Unknown Aerial Phenomena' — a 209-entry tabular log of sightings between August 1949 and May 1950. The log is organized by sighting number, date, location, witness description, and disposition. Locations cluster heavily around Sandia Base, Los Alamos, Kirtland AFB, Holloman AFB, Albuquerque, and Alamogordo, New Mexico. The summary represents the most comprehensive single-cluster UFO database the U.S. government compiled before Project Blue Book consolidated reporting in 1952.
Project SIGN, GRUDGE, and the AFSWP
The Sandia green-fireball investigation overlapped with USAF Project SIGN (the original 1948 UFO investigation program) and its successor Project GRUDGE. The Armed Forces Special Weapons Project — the direct post-WWII successor to the Manhattan Project — owned a parallel investigation because the sightings were concentrated over the U.S. nuclear-weapons complex. DOC-141 contains correspondence between Detachment D of the 1100th USAF Special Reporting Group, AFSWP Headquarters at Sandia Base, the Fourth Army, and the Strategic Air Command (SAC). The April 1949 Camp Campbell security inspection memo is the bundle's opening document.
Why this matters today
The Sandia bundle establishes that the U.S. government's earliest sustained UFO investigation was triggered specifically by sightings over nuclear-weapons facilities — not by Roswell or generic 'flying saucer' reports. This pattern recurs in later PURSUE records: the Department of Energy's Pantex Plant surveillance imagery (DOC-138), James Tuck's Los Alamos correspondence (DOC-139), and the 1986 Pajarito Astronomers UAP talk (DOC-140) all involve the same nuclear-handling sites. AARO does not formally connect the 1948–1950 cluster to modern UAP encounters, but the geographic and institutional continuity is documented in the primary record.