Nuclear Pulse Propulsion: Orion and Beyond
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AlAA 2000-3856 Nuclear Pulse Propulsion - Orion and Beyond G.R. Schmidt, J.A. Bunornetti and P.J. Morton NASA Marshall Space Flight Center Huntsville, Alabama 36th AIAMASMEEAWASEE Joint Propulsion Conference & Exhibit 16-19 July 2000 Huntsville, AIabam a AIAA 2000-3865 NLCLEAR PULSE PROPULSION - ORION AND BE\I*OND G.R. Schmidt,* J.A. Bonometti** and P.J. Morton+++ IWSA Marshall Space Flight Center, Huntsville, Alnbnnin 35812 A bgtract As alL\a>s. cost is a principal factor driving the need for systems with much greater performance. The race to the Moon dominated manned space However. when considering transportation of human flight during the 1960's. and culminated in Project crews over distances of billions of kilometers, safety Apollo. which placed 12 humans on the Moon. becomes an equal if not more important concern. The Unbeknownst to the public at that time, several U.S. biggest safety issues stem from the severe radiation government agencies sponsored a project that could environment of space and limitations imposed by have conceivably placed 150 people on the Moon, and human physiology and psychology. Although eventually sent crewed expeditions to Mars and the countermeasures. such as artificial graviw. could outer planets. These feats could have possibly been greatly mitigate these hazards. one of the most accomplished during the same period of time as straightforward remedies is to significantly reduce trip Apollo. and for approximately the same cost. The time by travelling at very high-energy. hyperbolic project. code-named Orion. featured an extraordinary trajectories. This will demand propulsion systems that propulsion method known as Niiclear Pulse can deliver far greater exhaust momentum per unit Pni,n:rlsioti. The concept is probably as radical todaj mass (i.e.. specific impulse or Isp) than modern-day as It was at the dawn of the space age. However. its chemical rockets. and thct can operate at significantlj de\ elopment appeared to be so promising that it was larger pouer densities than current high-performance o~l)hi. political and non-tzchnical considerations that electric propulsion s>stems. it ii as not used to extend humanity's reach throughout Many advanced propulsion concepts have been the solar system and quite possibly to the stars. This identified that could. at least theoretically. meet these paper discusses the rationale for nuclear pulse needs. The only problem is that virtually all of these propulsion and presents a general historq of the technologies. such as fusion. antimatter and beamed- concept. focusing particularly on Project Orion. It enerzy sails. have fundamental scientific issues and describes some of the reexaminations being done in practical weaknesses that must be resolved before they this area and discusses some of the new ideas that can be seriousl) considered for actual applications. could mitigate many of the political and environmental For instance. fusion is limited by the fact that we issues associated with the concept. are still far away from demonstrating a device having energy gains sufficient for commercial power. let alone Introduction space applications. Antimatter, while appealing due to its high specific energy, is severely hampered by The 20th century saw tremendous progress in the extremely low propulsion efficiencies and the high science and engineering of chemical rockets. These costs of current antimatter production methods. advances ushered in the deployment of extensive Beamed energy offers great potential too, but requires satellite systems in earth orbit, conveyance of materials far beyond current state-of-the-art and sophisticated scientific probes into the farthest reaches tremendous investment in power beaming of the solar system, and transport of humans to and infrastructure. from the Moon. Although these feats have been We are confident that many of these issues will impressive. chemical rocketry has more or less reached be overcome. but there is no guarantee that systems the limits of its performance. Accomplishing the based on these technologies could be fielded any time future goals of establishing human settlements on soon. This state-of-affairs points to the disappointing Mars. conducting rapid -'omniplanetary" transportation fact that none of the familiar advanced. high-power throughout the solar system. and eventually travelling density propulsion concepts could. with a any degree to the stars will require revolutionary advancements in of certainty. meet the goals of ambitious space flight propulsion capability . within the next 30 or even SO years. This is especially * [)eput! Ilanagcr. Propulhion Research Center. Sr. llembcr :\If\:\. *. \;uclc'ur f'ropul.;ic)n t3igincer. Propulsion Research Centcr. \Ismher \I \ \ ** Flight S! stems l-:ngincer. Propulsion Research Ccnter. llember .\I:\.\. Cop! right C 2000 by the American Institute of Aeronautics and Astronautics. Inc. No cop! right is asserted in the United States under Title 17. U.S. Code. The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed here for Governmental purposes. All other rights are reserved by the copyright owner. true in light ot'the consenative tiscal environment of These 5:udit.s identitit'd the two main issues in the post-Cold War era. \.\. hich could limit the jizable attaining a high Isp Lrirh this t>pe ofsjstem. First is inb estment needed to resol\ e the fundamental ij:UtS the snerg) per unit ma.. or \/?C'~.//i~,.i.it'l'lofthe associated with these conc2pts. Moreo\er. deb sloping detonations. The eftec:i~sexhaust Lelocit) and Isp are actual Lehicles based on these technologies Jnd their proponional to the square root of the energ) distributed required infrastructure could realisticall, cost on the over the entire mass of the explosive charge. and point order of hundreds of billions of dollars. to the need to achieve as high of specific yield as The rather bleak prospects for near-term high- possible. The second consideration is designing the Isp high-power densit! propulsion improve hou e\ cr Lehicle to cope \\ ith the mechanical and thermal effects \\hen we reconsider an ?xtraordinan concept :hat gren of the blast. I\ hich placss a maximum limit on the out of nuclear weapons research during World War 11. uti I i zable en erg! ,. This concept, Nuclear Pulse Propulsion (NPP). The next significant step was the idea of using an represents a radical departure from conventional explosive charge with much higher specific energy than approaches to propulsion in that it utilizes the highly dynamite. namely the atom bomb. In contrast with energetic and efficient energy release from nuclear chemical explosives. the specific energies of nuclear explosions directly to produce thrust. reactions are so high that vehicle design constraints At first it would seem ridiculous to think that will limit the performance before the energy limit is anything could survive the hundreds of thousand- reached. Uranium fission has an energy density of degree temperatures at the periphery of a nuclear -7.8 s 10- MI hg. corresponding tu a masiinum explosion. much less than the multi-million degree theoretical Isp of - i .3 Y IO6 sec. Surprisingly, this temperatures at the core. However as nuclear research value is only half the maximum Isp attainable from advanced in the 1950's and 1960's. it became apparent fusion of Deuterium and Helium-3. which yields a that some materials could survive a nuclear detonation. product kinetic energq equivalent to - 2.2 x 10' secs. and survive it well enough to provide a controllable .A proposal for us? of fission-based e\plosives ccni ersion of blast energ) into vehicle kinetic energ) 5rst made t; Stanislaus Ulani in 1946. followed blosr intriguing ot'all is that this approach could b! some preliminarq calculations by F. Reines and deliLer specific impulses bet\.ceen 10.000 secs up to L lam in 1947. The first full mathematical treatment of IO0.000 secs LV ith average power densities equal to or the concept was published b, Cornelius Everett and greater than chemical rockets. using existing Ulam in 1955. [3] The U.S. Atomic Energy technolog,. Commission was auarded a patent for the concept. The development of nuclear pulse propulsion termed "external nuclear pulse method." following during the 1950'5 and 1960's looked so promising that initial application in 1959. [J] it u as onlq through political and non-technical The earliest ph! sical demonstration and proof of circumstances that it neber became a realitq. The bulk the concept's merit occurred in an experiment of this work occurred under the Orior7 program. a 7- conceibed bj phjsicist Leu Allen. Code-named ,ear project sponsored b! the U.S. government from "Viper." the ekperiment \\as conducted at the Eniwetok 1958 to 1965. Had the program progressed to flight Island nuclear facilit) in the Pacific Ocean, and status. it is conceivable that the U.S. would have been involved detonating a 20-kiloton nuclear device IO able to place large bases on the Moon and send human meters away from two - 1 -meter-diameter. graphite- crews to Mars, Jupiter and Saturn within the same time coated steel spheres. [5] The wires holding the spheres period as Apollo, and possibly for the same cost. were vaporized immediately. but not so for the spheres It is highly unlikely that the Orion envisioned themselves, Some time later and several kilometers back then would be acceptable by today's political and from ground zero. the spheres were recovered, with environmental standards. However, it does provide an only a few thousandths of an inch of graphite ablated excellent starting point for presenting some new ideas from their surfaces. [6] Most importantly. their on nuclear pulse propulsion. which could deliver not interiors were completely unscathed. onl, better performance than the original concept but could mitigate many of the issues associated with Types of Concepts nuclear proliferation, environment contam ination.