AAWSAP DIRD, Positron Aerospace Propulsion, March 2010

This Defense Intelligence Reference Document was prepared by the Defense Intelligence Agency's Defense Warning Office and dated 2 March 2010. It is one of a series of advanced technology reports produced under the Advanced Aerospace Weapon System Applications program. It looks at using positrons as fuel for air-breathing turbojets, ramjet-assisted missiles, single-stage reusable vehicles and rockets for a manned Mars mission, and it also covers positron production, costs and storage. It concludes that a first positron-powered flight around the globe could be possible within 10 years.

From the source:Release of 2026-09-18 Incident: 3/2/10, Las Vegas, Nevada. Released with redactions. 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 positrons as a possible fuel for advanced aerospace propulsion, arguing that antimatter offers extraordinary energy density and could, in principle, support applications ranging from long-endurance aircraft and missiles to single-stage launch vehicles, onboard power systems, and crewed Mars missions. At the same time, it makes clear that the concept depends on resolving major unsolved problems in producing positrons in sufficient quantities and storing them safely for long periods, and much of the document’s discussion of flight systems and Mars missions remains conceptual rather than closely tied to demonstrated engineering practice. Its overall conclusion is that positron propulsion is theoretically attractive, but remains highly speculative as a practical technology because its core production and storage requirements remain unsolved.

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THE SANGER PHOTON POSITRON ROCKET
In 1953, German engineer Eugen Sanger proposed the photon rocket. One means of
providing thrust was to shower a parabolic mirror with positron annihilation gamma
rays .37 Unfortunately, there are no materials that reflect gamma rays at large angles.
A schematic of a mod ified Sanger photon rocket is shown in Figure 13. Ps is emitted in
' pellets' from several storage banks located behind the engine. Positrons are
programmed by supporting fields to annihilate in front of a stiffened pressure plate, the
shape of wh ich was assumed to be parabolic for this work. 38
To make the Sanger photon rocket practica l, solid propellant that can be ablated from
the plate is added. Gamma rays deposit energy on the surface of the ablation material
and jettison high-energy particles with large l sp . As the solid material recedes from the
target, the location of the positron annihilation can be corresponding ly moved inward to
preserve focal properties of the system. A thickness of a few meters of material is
sufficient for a planetary mission.
PEC SYSTEM
(OPTI ONAL)
e+ TRAP BANKS
SOLID ABLATION
MATERIAL
Figure 13. Modified Sanger Photon Rocket Concept (courtesy Positronics Research LLC) 39
The predicted l sp for this system results in fast transit times to Mars, warranting a
positron power plant. Unlike the solid-core or gas-core concepts, there are no means to
draw off some of the ablated material to provide power. A separate Brayton-cycle
positron energy conversion system provides power to the pellet mass driver and other
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