PURSUE Record — PURSUE R02 DOW-UAP-D017 — Sandia Green Fireballs (1948–1950): U.S. Department of War (formerly DoD) / Sandia Base records · Sandia Base, New Mex

PURSUE R02 DOW-UAP-D017 is a 116-page declassified PDF released on May 22, 2026 as part of PURSUE Release 02 by the U.S. Department of War — formerly the Department of Defense — drawing on Sandia Base records from New Mexico. It documents the formal U.S. government investigation into a series of anomalous green fireball sightings over one of the most sensitive military installations in the country between 1948 and 1950. This is primary-source bureaucratic and scientific correspondence, not a retrospective summary.

What this record contains

The document is catalogued as "General Correspondence of Sandia Base, Folder 333" and runs to 116 pages covering the green fireball investigation from 1948 through 1950. The releasing agency is the U.S. Department of War, drawing on records from Sandia Base, New Mexico — the installation now known as Kirtland Air Force Base. The release consists of a single file part. At its core are Dr. Lincoln La Paz's analytical memoranda, including his ten-point argument that the December 1948 fireball events were non-meteoric in character: the objects followed horizontal paths at low altitude, produced no audible sound, achieved full brightness instantaneously rather than building gradually, and consistently approached from the north half of the sky — a directional consistency La Paz considered inconsistent with random meteoric debris.

Beyond La Paz's analyses, the folder contains a 17th District OSI summary addressed to Brigadier General Joseph F. Carroll, a multi-page sightings catalog sorting reports into the categories "green fireball," "disc," and "probably-meteoric," and documentation of a copper-particle experiment conducted after a fireball event near Socorro on 24 July 1949 — an attempt to identify chemical composition from atmospheric residue. The record also contains materials relating to the Land-Air/Holloman contract, the procurement arrangement that eventually became Project Twinkle, the formal government sky-monitoring program spun out of this investigation.

Historical and documentary context

Sandia Base in 1948 was not an ordinary military installation. It was the primary U.S. nuclear weapons assembly and storage site — the place where the atomic bombs assembled at Los Alamos were prepared for operational deployment. That context explains why repeated, unexplained aerial phenomena over the base generated formal scientific and counterintelligence responses rather than dismissal. The late 1940s were also the period when the Air Force's Project Sign and Project Grudge were operational, meaning the green fireball investigation ran in parallel with — and fed into — the nascent institutional infrastructure for UAP analysis. Dr. Lincoln La Paz was not a fringe figure: he was a credentialed meteor scientist at the University of New Mexico, and his willingness to formally argue that the December 1948 events fell outside any known meteoric pattern gave the case bureaucratic weight it might otherwise have lacked.

The copper-particle experiment is an important detail in this record. After the 24 July 1949 Socorro fireball, investigators attempted to collect and analyze atmospheric particulates as a physical-evidence methodology — a notably systematic approach for the era. Whether that experiment yielded conclusive results is not detailed in the public release metadata, but its existence in this folder demonstrates that the investigation was not limited to witness testimony alone. The Land-Air/Holloman contract that followed represents the government's decision to fund continuous instrumental sky surveillance specifically in response to these events.

What this does and does not prove

What this record documents is that credentialed scientists and senior military officers, operating in a classified environment, formally concluded that a subset of the observed events resisted conventional meteoric explanation under the analytical standards of the time — and that this conclusion was serious enough to generate funded follow-on instrumented surveillance. That is a documented institutional response, and it is meaningful. What this record does not establish is the origin, nature, or physics of the objects observed. La Paz's ten-point argument is documented here as his contemporaneous analysis; it is not an endorsed finding of anomalous origin. The sightings catalog's "probably-meteoric" category illustrates the investigators' own analytical discipline: some events were categorized as conventional even while others were not. The public release does not include detailed metadata on the outcome of the copper-particle experiment or on Project Twinkle's final findings.

How it fits PURSUE Release 02

PURSUE Release 02, published May 22, 2026, extends the Department of War's declassification effort deeper into the foundational documentary record of U.S. UAP investigation. DOW-UAP-D017 sits within the release's archival PDF layer — the category of historic correspondence, OSI reporting, and interagency correspondence that provides institutional paper trails for cases that have remained formally unresolved for decades. Alongside the other Department of War records in this release, it helps establish that organized, scientifically-informed investigation of anomalous aerial phenomena over sensitive installations was occurring at the highest classification levels well before UAP became a matter of public congressional debate. For additional context on related records from the release, see the SkyLens UAP files page and our broader PURSUE coverage.

Editorial note: This analysis is independent commentary on a publicly released document. The original record, source links, and full release metadata are catalogued on the SkyLens UAP files page alongside every other case in the PURSUE Release 01 set.