UNCLASSIFIED // PUBLIC RELEASERELEASE 06 · SEPTEMBER 18, 2026
PENTAGON UFO FILE · DOCUMENT · DOW-UAP-D126AAWSAP DIRD, Advanced Nuclear Propulsion for Manned Deep Space Missions, March 2010
This DIRD is a theoretical paper on how people might one day travel well beyond the Moon. Written for the Pentagon’s AAWSAP in March 2010, it is described in the release as an engineering study, not a sighting report. Its question: what kind of engine could carry a crew across the solar system in a reasonable time.
Bombs as an engine
The author’s starting point is that a crewed deep-space ship needs two things at once that rarely come together: strong thrust and very efficient use of propellant. Chemical rockets, reactor-heated nuclear rockets and electric thrusters each fall short on one count or the other, the paper contends.
Its answer draws on Project Orion, the abandoned General Atomics study in which a ship would ride a series of nuclear detonations against a pusher plate. Rather than small fission bombs, which the paper sees as wasteful, it favors little fusion explosions of deuterium set off without a fission trigger, using magnetic mirrors and other unusual ways of starting the reaction. The release stresses that these ignition schemes are unproven and that the paper is a theoretical examination, not an account of hardware close to working.
Terms worth knowing
“Specific impulse” is the standard measure of how much push an engine gets from each unit of propellant; high thrust and high specific impulse are usually a trade-off. Orion-style pulse propulsion is attractive on paper because it promises both. A related paper in the same series is Aneutronic Fusion Propulsion I.
The official description
From war.gov/UFO, released September 18, 2026, quoted in full
This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed.
This DIRD examines advanced nuclear propulsion for crewed deep-space travel and argues that human missions beyond the Moon would require propulsion systems with both very high thrust and very high specific impulse, which the author contends are difficult to achieve with conventional chemical, nuclear-thermal, and nuclear-electric systems. The report focuses on concepts derived from Project Orion, the discontinued General Atomics nuclear pulse propulsion study sponsored first by ARPA and later by the U.S. Air Force between 1958 and 1965, in which a spacecraft would be driven by repeated nuclear explosions. In this case, the DIRD emphasizes small non-fission-triggered fusion explosions using deuterium, magnetic mirrors, and other unconventional ignition concepts intended to avoid the inefficiencies associated with small fission devices. It presents these ideas as a possible pathway to crewed missions across the solar system, while also linking them to broader visions of long-range human expansion into space. The document is exploratory in character and depends on several unproven ignition methods, enabling technologies, and engineering assumptions. Overall, it is a theoretical examination of fusion-based pulse propulsion concepts rather than as a documentary account of a technology nearing practical realization.