STM-D-0949Paper2002Designed, not yet built

Project Orion and Future Prospects for Nuclear Pulse Propulsion

G. R. Schmidt · J. A. Bonometti · C. A. Irvine

Abstract and summary · read the original at the source · none found

In one page

While Apollo was being built in public, another American programme was being built in secret, and it was aiming much further. George Schmidt, Joseph Bonometti and C. A. Irvine of NASA’s Marshall Space Flight Center tell that story in a propulsion journal and then ask the engineering question underneath it. Project Orion, run from 1958 to 1965, would have driven a ship by dropping small nuclear charges behind it and letting each explosion slap a heavy pusher plate. The authors are precise about why it stopped: not because anyone found a technical reason it would not work, but because of politics, a test-ban treaty and the absence of a mission that demanded it. Many of the engineers who met the programme came away convinced. The paper then presents what has changed since — new materials for the plate, and a fission scheme in which the vehicle compresses a subcritical target itself, so it carries no bombs at all.

Why it matters hereChapter 8 is about what a craft can do once its performance is no longer set by chemistry, and nuclear pulse is the highest-performing propulsion architecture that has ever been through hardware testing — the ceiling of what you can reach while you are still throwing mass out of the back. Chapter 12 gets the sequel the authors themselves point to: once the pulse is a fusion microexplosion rather than a fission charge, the pusher plate becomes a magnetic field and the driver becomes a laser.

What it claims

01This is the paper’s own headline and it is stated without hedging. Several U.S. government agencies sponsored a project that could conceivably have placed large bases on the Moon and eventually sent crewed expeditions to Mars and the outer planets within the same period of time as Apollo, and for approximately the same cost.Abstract, second sentence
Published and peer-reviewed
02The reason it stopped was never a physics reason. Its feasibility was never dismissed on purely technical grounds; in fact, many of the scientists and engineers who came into contact with the programme over its seven-year lifetime became convinced of its viability, and it was political and nontechnical issues that finally sealed its fate.Abstract, fifth to seventh sentences
Published and peer-reviewed
03The performance case is what makes the concept worth reopening. Nuclear pulse propulsion could deliver specific impulse from about 10,000 seconds up to about 100,000 seconds at average power densities equal to or greater than chemical rockets, using existing technology; in the external configuration, where the charge goes off behind an unshielded pusher plate, ablation of the plate limits the impingement velocity to roughly 100 to 200 kilometres per second and the achievable specific impulse to roughly 3,000 to 10,000 seconds.Predecessor NASA paper, Nuclear Pulse Propulsion — Orion and Beyond, AIAA 2000-3856, introduction and the section Types of Concepts
Designed, not yet built
04The ship was designed in detail, not sketched. The vehicle stood about 80 metres high behind a pusher plate about 40 metres across, would have massed on the order of 10,000 tonnes at takeoff, and would have ejected 0.1-kiloton pulse units at one per second on the pad, slowing to 20-kiloton pulses every ten seconds as it accelerated. The original design called for 2,000 pulse units, one hundred and fifty people could have lived aboard, and the useful payload was measured in thousands of tonnes.Predecessor NASA paper, AIAA 2000-3856, section Project Orion, The Beginning 1957 to 1958
Designed, not yet built
05Two pieces of hardware evidence sit under the whole concept. In the Eniwetok test conceived by Lew Allen, a 10-kiloton device was detonated ten metres from two graphite-coated steel spheres about a metre across; the wires holding them vaporised instantly, the spheres were recovered kilometres away with only a few thousandths of an inch of graphite ablated, and their interiors were completely unscathed. And the Putt-Putt flight models, driven by chemical charges, flew 100 metres on six charges in November 1959 and showed that impulsive flight is stable.Predecessor NASA paper, AIAA 2000-3856, sections Origin of the Concept and The ARPA Year 1958 to 1960
Published and peer-reviewed
06What to watch is the version that carries no bombs. In a microfission scheme the spacecraft compresses a subcritical target of fissile material with its own onboard driver, exactly as a fusion pellet is compressed — and the energy needed to drive a fission sample supercritical is substantially less than for the comparable fusion process. Because the energy comes from the ship, such a system cannot be used as a weapon in any conventional way, which removes the storage and proliferation objections at a stroke. Only a few studies of this approach have been done, and the authors call it a realistic intermediate step between today’s propulsion and the fusion-propelled concepts of tomorrow.Predecessor NASA paper, AIAA 2000-3856, section Reconsidering Nuclear Pulse Propulsion
What to watch

Read it · abstract

Abstract

The race to the Moon dominated human space flight during the 1960s and culminated in Project Apollo, which placed 12 men on the lunar surface. Unbeknownst to the public at that time, several U.S. government agencies sponsored another project that could have conceivably placed large bases on the moon and eventually sent crewed expeditions to Mars and the outer planets within the same period of time as Apollo, and for approximately the same cost. The project, code-named Orion, featured an extraordinary propulsion method known as nuclear pulse propulsion. First conceived at the dawn of the space age, the concept was as radical then as it is now. However, its feasibility was never dismissed on purely technical grounds. In fact, many of the scientists and engineers who came into contact with the program over its seven-year lifetime became convinced of its viability. The political and nontechnical issues that finally sealed the program’s fate would certainly make the original Orion unacceptable by today’s standards. However, new technologies and ideas developed since then could mitigate some of the major issues, and make nuclear pulse propulsion less unreasonable to consider for future human exploration, at least beyond Mars orbit. These new approaches are presented, following a discussion of the technological rationale for nuclear pulse propulsion and a general history of the concept.

G. R. Schmidt, J. A. Bonometti and C. A. Irvine, NASA Marshall Space Flight Center, Huntsville, Alabama. Journal of Propulsion and Power 18, number 3, pages 497 to 504 (2002). Abstract as deposited by the publisher, with four lost ligatures restored — see the rights note above.

(Abstract only — the eight pages of history, performance analysis and new concepts are at the source. The predecessor NASA conference paper by two of the same authors, which the engineering claims above are located against, is public on the NASA Technical Reports Server under accession 20000096503.)

The propulsion neighbours on this site: the gasdynamic-mirror fusion rocket and its trip times are at /library/stm-1d903a7f60; inertial confinement fusion turned into a propulsion system, the direct descendant of the fusion-microexplosion concepts named here, is at /library/stm-b87332054a; the Defense Intelligence reports on advanced nuclear propulsion for crewed deep-space missions and on aneutronic fusion propulsion are at /library/stm-c75846c5a6, /library/stm-b5e092d030 and /library/stm-08b7559cf0; Marc Millis and Eric Davis’s AIAA volume on what comes after mass ejection is at /library/stm-c06140bc7a; and the study that scores every interstellar architecture against the others is at /library/stm-00a7ce4729.

The way in

https://doi.org/10.2514/2.5969WHAT THIS IS. Journal of Propulsion and Power volume 18, number 3, pages 497 to 504, May to June 2002. All three authors are given by the publisher record as NASA Marshall Space Flight Center, Huntsville, Alabama 35812. LICENCE. The AIAA article is closed: Crossref records no licence, Unpaywall and OpenAlex both report it closed with no repository copy, and Semantic Scholar returns a publisher-elided record — all checked 2026-09-08. So no text of the journal article is reproduced here beyond the author’s own abstract. THE ABSTRACT. Reproduced from the publisher’s own deposit, read on 2026-09-08 through the Crossref record and the OpenAIRE publications API, which agree word for word. That deposit lost its fi and fl ligatures in conversion, printing ‘space e ight’ for ‘space flight’ and ‘that e nally’ for ‘that finally’; the four affected words are restored and the spacing of two possessives is closed up. Nothing else is altered. NTRS. The NASA Technical Reports Server does not hold this journal article. It does hold the predecessor conference paper by two of the same three authors — G. R. Schmidt, J. A. Bonometti and P. J. Morton, ‘Nuclear Pulse Propulsion: Orion and Beyond’, AIAA 2000-3856, presented at the 36th Joint Propulsion Conference, Huntsville, 16 to 19 July 2000, NTRS accession 20000096503, whose first page carries the line ‘No copyright is asserted in the United States under Title 17, U.S. Code’. That paper is a different document with a different third author, so this sheet is not promoted past abstract-only; but it was downloaded from NTRS and read in full on 2026-09-08, and the three claims below that carry engineering figures are located against its named sections. Its scan is an imperfect optical character recognition of a 2000 print, so only figures that are unambiguous in that scan are stated here. AUTHOR NAMES. Publisher and NTRS records give the first author as G. R. Schmidt and, on the NTRS citation, as George R. Schmidt; the other two are printed with initials in both records and are left that way.

How to cite it

G. R. Schmidt, J. A. Bonometti, C. A. Irvine (2002) Project Orion and Future Prospects for Nuclear Pulse Propulsion. doi:10.2514/2.5969

Where it sits in the curriculum

Inertial mass reduction and transmedium craft Lattice confinement fusion