AIAA 2000-3856 Nuclear Pulse Propulsion - Orion and Beyond G.R. Schmidt, J.A. Bonometti and P.J. Morton NASA Marshall Space Flight Center Huntsville, Aiabama 36th AI AAIASMElSAElASEE Joint Propulsion Conference & Exhibit 16- 19 J u IY 2000 Huntsville, Alabama For perlllBsKa to copy or to repIbliU, amta.ct fie Ante.rDI bstitI~ ofAerouItD iWl.l\strmaI - 9 1801 Al.e:mIder Ben Dri~ SIne 500, RestoI, VA, 20191-4344. r- --- AIAA 2000-3865 NUCLEAR PtrL SE PROPCLSION - ORIO:\f A.'I'D I3EYOND C .R. Schmidt,· J.A. Bonometti** and P.J. Morton*"'* NASA ,yfarshall Space Flight Center, Huntsville, Alabama 35812 Abstract As alway . cost is a principal fa ctor driving the need for systems with much greater performance. The race to the Moon dominated manned space However. when considering transportation of human fl ight during the 1960's. and cu lminated in Project crews over di stances of bill io ns of ki lometers, safety Apollo. which placed 12 humans on the Moon. become an qual ifnOl more im portant concern. The Unbeknownst to th e publ ic at that time, several U.S. biggest safety issues stem from th e severe radiation government agencies sponsored a project that could environm ent of space and lim itations imposed by have conceivably placed I SO people on the Moon, and hu man ph ys iology and psycho logy. Although eventually sen t crewed ex peditions to Mars and the countermeasures. such as artific ial gravity. could outer planets. These feats could have possibly been greatly mitiga te these hazard. one of th e most accomplished during the same period of time as straightforward remedies i to sign ifi cantly reduce trip Apollo. and for approximate ly the same cost. The time by travelling at ve ry hi gh -energy. hyperbolic proj ect. code-named Orion. featured an extraordinary trajectories. This will demand propulsion systems that propul sion method known as Nuclear Puls e can deliver far greater exhaust momentum per unit Prup!ti ·ion. The co nc~pt is probably as rad ical today mass (i.e .. specific im pul se or Isp) than modern-day as It lI as at the dawn of th e space ag e. However. its chemical rockets. and thN can operate at signiticantl y de\'elopment appeared to be so promising that it was larger power de nsities than CUITe nt hi gh-performance onl~ b) political and non -technica l considerations that ~Iectric propulsion ys teill s. it lIas not used to extend humanity's reach throughout Many advanc ed propulsion concepts ha ve been the so lar system and quite possibly to the stars. Thi identified that co uld . at least theoreticall y. meet these paper discusses the ratio nale for nuclear pulse needs. The on ly prob lem is that vi rtually all of these propulsion and presents a general history of the technologies. such as fusion . antimatter and beamed­ concept. focusing pal1icularly on Project Orion. It energy sa il s. have fun damental scientific iss ue and describes ome of th e reexamination being done in practical weaknesse that mu t be reso lved before they thi s area an d discus es ome of the new ideas that can be se riou s I: considered fo r actual application s. could mitigate many of the po litical and environmental For instance. fus ion is limited by the fact that we is ues associated with the co ncept. are still fa r away from demonstrating a device having energy ga ins sufficient for commerc ial power, let alone Introduction space app lications. Antimatter, while appealing du e to its hi gh spec ific energy. is severely hampered by The 20th century saw tremendous progress in the extremely low propulsion efficienci es and the hi gh sc ience 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 sc ientific probes into the farthest reaches tremendous in vestmen t in power beaming of the solar system . and transport of hum ans to and infrastructu re. from the Moon . A Itho ugh these fea ts have been We are confident that man y of these issues wi ll impress ive. chemical rocketry has mo re or less reached be overcome. but there is no guarantee that system s the limits of its performance. Accom plish ing th e based on these technologies cou ld be fielded any tim e future goals of establishing human se ttl ements on soon. This state-of-affairs points to the disappo in ting lars. conducting rapid "omniplanetary" transportation fact that none of the fam iI iar advanced. high-power throughout the so lar sys tem. and eventuall y travelling density propul sio n concepts co uld. with a any degree to the stars will require revolutionary advancements in of certainty. meet the goals of ambitious space flight propulsion capabi lit y. withi n the ne xt 30 or even 50 yea rs. This is es pecially Lkput> 'v li.lllag.er. Propul sion Resea rch Cc: nter. ·r. :Vk mb.:r ,\IAr\. ~u<:kar Propul sio n Engin.:er. Prop ul sio n Re "c:an:h C':lller. :Vkmb.:r . \ 1. \ . \ . • • Flight :> st.:m s Engi nee r. Propul sion Research Ce nter. Member AI,\ , \ . C()p~ righ t C :1000 b. the Ame rican Institute of Aero nautics and As tronautic s. Inc. No cop~ ri ght is asserted in the United States under Title 17. Code. The U. S. Gove rnm ent has a royalty -free license to exerc ise all rights under the copyright daimed here fo r Govemmental purposes . All oth er rights are reserved by the copyright owne r. true in light of the conservative fiscal envi ronme nt of These studies identified the two mai n issue in the po t- Co ld War era. "hich co uld limit the sizable anai ning a high Isp 1\ ilh [hi s rype of system. First is investment needed to reso lle the fundamenta l issu e- the energ; per unit mas- or speC/jic rield of the a sociated with these concept Moreoler. de'elo pi ng de to nati ons. The effectile exhau t \elocit: and Isp are actual vehi cles based on these technol ogi s and the ir proporti onal to the qua re root of the energ) di tributed required infrastructure could rea listicall, CO St on the ove r th e entire mas of the ex plos ive charge. and point order of hundred s of billi ons of do llars. to the need to achieve as high of specific yield as The rather bleak pros pects fo r near- te rm high ­ po sible. The second consideration is design ing the Isp high-power density propulsion improve hOII'eler vehicle to cope II ith the mec han ical and thermal effects \\ hen we reconsider an extraord ina ry concept that gre\1 of the blast. \\'hich pl ace a maximum limit on the Out of nuc lear weapons research during Wo rl d War II. ut ilizable energy. This concept, Nuclear Pulse Propulsion (NPP) . The next significant step was th e idea of using an represents a radical departure from conventional expl osive charge \:,:, ith much hi gher specific energy than approaches to propul sion in that it uti lizes the high ly d, namite. name ly the atom bom b. In contrast with energeti c and effic ient energy release fro m nuc lear chemical explosives. the specific energies of nuclear explosions directly to produce thrust. reactions are so high that ve hic le des ign constraints At first it wo uld seem ridiculous to think that will Iim it the performance before the energy Ii m it is an yth ing could survive the hundreds of thousand­ reached. Uranium fis sion has an energy density of degree temperatures at the periphery of a nuclear - 7.8 x 10- MJ kg. corresponding to a maximum explosion . much le ss th an the mu lti -million degree theoretical Isp of - 1.3 x 106 sec. urprisingl y, th is temperatures at the core. However as nuc lear research value is only half the maxim um Isp attainable from advanced in the 1950's and 1960's. it became apparent fu sion of Deuterium and Helium-3. which yields a that some materials could surv ive a nuc lear detonation . product kinetic energy equiva lent to - 2.2 x 106 secs. and survi ve it we ll enough to provide a con tro llabl e A propo al for use of fission -based explosives comersion of blast energy into vehicle kin etic energ; . was first made b) tani slaus Ulam in 1946. followed Most intrigu ing of all is that th is approach cou Id b: some preliminary calculatio ns by F. Reines and deli\er ' pecific impul e between 10.000 secs up to ulam in 19-17 . The [-,rst full math ematical treatm ent of 100.000 secs with average power densitie equa l to or the concept wa publi hed by Cornelius Everett and greater than chem ical rockets. us ing existing Ula m in 1955 . (3] Th e .S. Atomic Energy tec hn ology . Commi sion was awarded a patent for the concept, Th e development of nuclear pul se propulsion termed "external nucl ear pu lse method." following during th e 1950' s and 1960's looked so promising that in itial appl icati on in 1959.