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Assessment of the advantages and feasibility of a nuclear rocket

Description: The feasibility of rebuilding and testing a nuclear thermal rocket (NTR) for the Mars mission has been investigated. Calculations indicate that an NTR would substantially reduce the earth-orbit assembled mass compared to LOX/LH/sub 2/ systems. The mass savings were 36% and 65% for the cases of total aerobraking and of total propulsive braking respectively. Consequently, the cost savings for a single mission of using an NTR, if aerobraking is feasible, are probably insufficient to warrant the NTR development. If multiple missions are planned or if propulsive braking is desired at Mars and/or at Earth, then the savings of about $7B will easily pay for the NTR development. Estimates of the cost of rebuilding a NTR were based on the previous NERVA program's budget plus additional costs to develop a flight ready engine. The total cost to build the engine would be between $4 to 5B. The concept of developing a full-power test stand at Johnston Atoll in the Pacific appears very feasible. The added expense of building facilities on the island should be less than $1.4B.
Date: January 1, 1985
Creator: Howe, S.D.
Partner: UNT Libraries Government Documents Department

Anti-matter propulsion: feasibility, status, and possible enhancement

Description: The possible use of advanced propulsion techniques must be considered if the currently envisioned launch date of the Manned Mars Mission were to be delayed until 2020 or later. Within the next 30 years, technological advances may allow such methods as beaming power to the ship, inertial-confinement fusion, or mass-conversion of anti-protons to become feasible. Of the possible methods, the anti-proton (anti p), reaction offers the highest potential, the greastest problems, and the most fascination. An Isp of 5000 s would allow the currently envisioned ship to fly to Mars in 3 months and would require about one million pounds to be assembled in Earth orbit. Anti-protons are currently being produced in the world in amounts of about 10/sup 14/ particles per year. With sufficient effort, almost a mg/yr (6 x 10/sup 20/) could be produced by the early 2000s. Current experiments plan to decelerate and capture about 10/sup 10/ or greater anti-protons in an electrostatic Penning trap. Such traps may provide a source of low energy anti p's for development of better storage mechanisms suitable for propulsion. Recently, proposals have been investigated which would amplify the average energy released per anti p used. The proposals entail using the anti p's to produce inertial confinement fusion of a capsule or to produce negative muons which can catalyze fusion. By increasing the energy released per anti p, the effective specific cost, $/joule, can be reduced to attractive levels. These two proposals and other areas of research can be investigated now and will help in assessing the feasibility of an anti p engine.
Date: January 1, 1985
Creator: Howe, S.D.
Partner: UNT Libraries Government Documents Department

Excitation of lasing media using antiproton-annihilation products

Description: Lasing has been achieved in many different media using a wide variety of excitation mechanisms including low-energy electron or proton beams and recoiling fission products. In all cases, the power density produced in the medium has been the critical parameter. Recent calculations indicate that a region of high-power density can be achieved in high-density lasing media by allowing antiprotons to annihilate in the material with an intense magnetic field present. Because of the long range of energetic annihilation products, the media can be gaseous, liquid, or solid. The thermalization time is the critical parameter for this excitation mechanism which for liquid-density media, such as Ar-Xe mixtures, is about 2.1 ns. Based on these calculations power density of about 100 MW/cm/sup 2/ can be achieved using a level of antiprotons that is currently available today. Development of an antiproton pumping source may allow fundamental reaction kinetics in a wide variety of lasing systems to be performed in a university environment. The results of the calculations in a liquid medium and at different magnetic field strength will be presented. In addition, the design of an ongoing experiment using an 800 MeV proton beam to pump a liquid density excimer cavity will be discussed. These preliminary experiments intend to focus on fundamental kinetics and on the effects of a strong magnetic field on reactions. 13 refs., 7 figs.
Date: January 1, 1988
Creator: Howe, S.D. & Hynes, M.V.
Partner: UNT Libraries Government Documents Department

Portable Pbars, traps that travel

Description: The advent of antiproton research utilizing relatively small scale storage devices for very large numbers of these particles opens the possibility of transporting these devices to a research site removed from the accelerator center that produced the antiprotons. Such a portable source of antiprotons could open many new areas of research and make antiprotons available to a new research community. At present antiprotons are available at energies down to 1 MeV. From a portable source these particles can be made available at energies ranging from several tens of kilovolts down to a few millielectron volts. These low energies are in the domain of interest to the atomic and condensed matter physicist. In addition such a source can be used as an injector for an accelerator which could increase the energy domain even further. Moreover, the availability of such a source at a university will open research with antiprotons to a broader range of students than possible at a centralized research facility. This report focuses on the use of ion traps, in particular cylindrical traps, for the antiproton storage device. These devices store the charged antiprotons in a combination of electric and magnet fields. At high enough density and low enough temperature the charged cloud will be susceptible to plasma instabilities. Present day ion trap work is just starting to explore this domain. Our assessment of feasibility is based on what could be done with present day technology and what future technology could achieve. We conclude our report with a radiation safety study that shows that about 10/sup 11/ antiprotons can be transported safely, however the federal guidelines for this transport must be reviewed in detail. More antiprotons than this will require special transportation arrangements. 28 refs., 8 figs.
Date: October 1, 1987
Creator: Howe, S.D.; Hynes, M.V. & Picklesimer, A.
Partner: UNT Libraries Government Documents Department

Nuclear data needs for the space exploration initiative

Description: On July 20, 1989, the President of the United States announced a new direction for the US Space Program. The new Space Exploration Initiative (SEI) is intended to emplace a permanent base on the Lunar surface and a manned outpost on the Mars surface by 2019. In order to achieve this ambitious challenge, new, innovative and robust technologies will have to be developed to support crew operations. Nuclear power and propulsion have been recognized as technologies that are at least mission enhancing and, in some scenarios, mission enabling. Because of the extreme operating conditions present in a nuclear rocket core, accurate modeling of the rocket will require cross section data sets which do not currently exist. In order to successfully achieve the goals of the SEI, major obstacles inherent in long duration space travel will have to be overcome. One of these obstacles is the radiation environment to which the astronauts will be exposed. In general, an unshielded crew will be exposed to roughly one REM per week in free space. For missions to Mars, the total dose could exceed more than one-half the total allowed lifetime level. Shielding of the crew may be possible, but accurate assessments of shield composition and thickness are critical if shield masses are to be kept at acceptable levels. In addition, the entire ship design may be altered by the differential neutron production by heavy ions (Galactic Cosmic Rays) incident on ship structures. The components of the radiation environment, current modeling capability and envisioned experiments will be discussed.
Date: January 1, 1991
Creator: Howe, S.D. & Auchampaugh, G.
Partner: UNT Libraries Government Documents Department


Description: It is apparent the cost of planetary exploration is rising as mission budgets declining. Currently small scientific beds geared to performing limited tasks are being developed and launched into low earth orbit (LEO) in the form of small-scale satellite units, i.e., CubeSats. These micro- and nano-satellites are gaining popularity among the university and science communities due to their relatively low cost and design flexibility. To date these small units have been limited to performing tasks in LEO utilizing solar-based power. If a reasonable propulsion system could be developed, these CubeSat platforms could perform exploration of various extra-terrestrial bodies within the solar system engaging a broader range of researchers. Additionally, being mindful of mass, smaller cheaper launch vehicles (approximately 1,000 kgs to LEO) can be targeted. Thus, in effect, allows for beneficial exploration to be conducted within limited budgets. Researchers at the Center for Space Nuclear Research (CSNR) are proposing a low mass, radioisotope-based, dual-mode propulsion system capable of extending the exploration realm of these CubeSats out of LEO.
Date: February 1, 2014
Creator: Jerred, N. D.; Howe, T. M.; Howe, S. D. & Rajguru, A.
Partner: UNT Libraries Government Documents Department

Gas core nuclear rocket feasibility project

Description: The next giant leap for mankind will be the human exploration of Mars. Almost certainly within the next thirty years, a human crew will brave the isolation, the radiation, and the lack of gravity to walk on and explore the Red planet. However, because the mission distances and duration will be hundreds of times greater than the lunar missions, a human crew will face much greater obstacles and a higher risk than those experienced during the Apollo program. A single solution to many of these obstacles is to dramatically decrease the mission duration by developing a high performance propulsion system. The gas core nuclear rocket (GCNR) has the potential to be such a system. The gas core concept relies on the use of fluid dynamic forces to create and maintain a vortex. The vortex is composed of a fissile material which will achieve criticality and produce high power levels. By radiatively coupling to the surrounding fluids, extremely high temperatures in the propellant and, thus, high specific impulses can be generated. The ship velocities enabled by such performance may allow a 9 month round trip, manned Mars mission to be considered. Alternatively, one might consider slightly longer missions in ships that are heavily shielded against the intense Galactic Cosmic Ray flux to further reduce the radiation dose to the crew. The current status of the research program at the Los Alamos National Laboratory into the gas core nuclear rocket feasibility will be discussed.
Date: September 1997
Creator: Howe, S. D.; DeVolder, B.; Thode, L. & Zerkle, D.
Partner: UNT Libraries Government Documents Department

Assessment of a hot hydrogen nuclear propulsion fuel test facility

Description: Subsequent to the announcement of the Space Exploration Initiative (SEI), several studies and review groups have identified nuclear thermal propulsion as a high priority technology for development. To achieve the goals of SEI to place man on Mars, a nuclear rocket will operate at near 2700K and in a hydrogen environment at near 60 atmospheres. Under these conditions, the operational lifetime of the rocket will be limited by the corrosion rate at the hydrogen/fuel interface. Consequently, the Los Alamos National Laboratory has been evaluating requirements and design issues for a test facility. The facility will be able to directly heat fuel samples by electrical resistance, microwave deposition, or radio frequency induction heating to temperatures near 3000K. Hydrogen gas at variable pressure and temperatures will flow through the samples. The thermal gradients, power density, and operating times envisioned for nuclear rockets will be duplicated as close as reasonable. The post-sample flow stream will then be scrubbed and cooled before reprocessing. The baseline design and timetable for the facility will be discussed. 7 refs.
Date: January 1, 1991
Creator: Watanabe, H.H.; Howe, S.D. & Wantuck, P.J.
Partner: UNT Libraries Government Documents Department

Spallation target-moderator-reflector studies at the Weapons Neutron Research facility. [800-MeV p]

Description: Basic neutronics data, initiated by 800-MeV proton spallation reactions, are important to spallation neutron source development and electronuclear fuel production. Angle-dependent and energy-dependent neutron production cross sections, energy-dependent and total neutron yields, thermal and epithermal neutron surface and beam fluxes, and fertile-to-fissile conversion ratios are being measured. The measurements are being done at the Weapons Neutron Research facility on a variety of targets and target-moderator-reflector configurations. The experiments are relevant to the above applications, and provide data to validate computer codes. Preliminary results are presented and compared to calculated predictions. 13 figures.
Date: January 1, 1980
Creator: Russell, G.J.; Gilmore, J.S.; Prael, S.D.; Robinson, H. & Howe, S.D.
Partner: UNT Libraries Government Documents Department

Neutron spectrum at 90/sup 0/ from 800 MeV (p,n) reactions on a Ta target

Description: The neutron time-of-flight spectrum produced by a thick tantalum target bombarded by 800-MeV protons was measured at an angle of 90/sup 0/. The data were taken at the Weapons Neutron Research facility by use of a cylindrical Ta target with a radius of 1.27 cm and a length of 15 cm. An NE-213 liquid scintillator was used to detect the neutrons over an energy range of 0.5 to 350 MeV. The neutron yield is presented and compared to a intranuclear-cascade/evaporation model prediction. 3 figures.
Date: January 1, 1979
Creator: Howe, S.D.; Lisowski, P.W.; King, N.S.P.; Russell, G.J. & Donnert, H.J.
Partner: UNT Libraries Government Documents Department

Potential applicability of the Los Alamos Antiproton Research Program to advanced propulsion

Description: The Los Alamos National Laboratory currently has a research program in antimatter interactions. The immediate objective of the program is to develop the low energy antiproton production capabilities at LEAR and the technology to store antiprotons. The initial experimental goal is to measure the gravitational mass of antiprotons. The technology required for the experiment, however, may allow high-density storage concepts to be experimentally investigated. Analysis of antiproton production over the last 30 years indicates that milligram quantities of antiprotons could conceivably be produced early in the next century. Thus, antiproton propulsion concepts may begin to be feasible. Some results of preliminary calculations pertinent to antiproton powered rocket engines will be presented.
Date: January 1, 1986
Creator: Howe, S.D.; Hynes, M.V.; Prael, R.E. & Stewart, J.D.
Partner: UNT Libraries Government Documents Department

Characteristics of the WNR: a pulsed spallation neutron source

Description: The Weapons Neutron Research facility (WNR) is a pulsed spallation neutron source in operation at the Los Alamos National Laboratory. The WNR uses part of the 800-MeV proton beam from the Clinton P. Anderson Meson Physics Facility accelerator. By choosing different target and moderator configurations and varying the proton pulse structure, the WNR can provide a white neutron source spanning the energy range from a few MeV to 800 MeV. The neutron spectrum from a bare target has been measured and is compared with predictions using an Intranuclear Cascade model coupled to a Monte Carlo transport code. Calculations and measurements of the neutronics of WNR target-moderator assemblies are presented.
Date: January 1, 1982
Creator: Russell, G.J.; Lisowski, P.W.; Howe, S.D.; King, N.S.P. & Meier, M.M.
Partner: UNT Libraries Government Documents Department


Description: The exploration of planetary surfaces and atmospheres may be enhanced by increasing the range and mobility of a science platform. Fundamentally, power production and availability of resources are limiting factors that must be considered for all science and exploration missions. A novel power and propulsion system is considered and discussed with reference to a long-range Mars surface exploration mission with in-situ resource utilization. Significance to applications such as sample return missions is also considered. Key material selections for radioisotope encapsulation techniques are presented.
Date: September 1, 2010
Creator: O'Brien, R. C.; Howe, S. D. & Werner, J. E.
Partner: UNT Libraries Government Documents Department

Safe testing nuclear rockets economically

Description: Several studies over the past few decades have recognized the need for advanced propulsion to explore the solar system. As early as the 1960s, Werner Von Braun and others recognized the need for a nuclear rocket for sending humans to Mars. The great distances, the intense radiation levels, and the physiological response to zero-gravity all supported the concept of using a nuclear rocket to decrease mission time. These same needs have been recognized in later studies, especially in the Space Exploration Initiative in 1989. One of the key questions that has arisen in later studies, however, is the ability to test a nuclear rocket engine in the current societal environment. Unlike the RoverMERVA programs in the 1960s, the rocket exhaust can no longer be vented to the open atmosphere. As a consequence, previous studies have examined the feasibility of building a large-scale version of the Nuclear Furnace Scrubber that was demonstrated in 1971. We have investigated an alternative that would deposit the rocket exhaust along with any entrained fission products directly into the ground. The Subsurface Active Filtering of Exhaust, or SAFE, concept would allow variable sized engines to be tested for long times at a modest expense. A system overview, results of preliminary calculations, and cost estimates of proof of concept demonstrations are presented. The results indicate that a nuclear rocket could be tested at the Nevada Test Site for under $20 M.
Date: January 1, 2002
Creator: Howe, S. D. (Steven D.); Travis, B. J. (Bryan J.) & Zerkle, D. K. (David K.)
Partner: UNT Libraries Government Documents Department

Reducing the risk to Mars: The gas core nuclear rocket

Description: The next giant leap for mankind will be the human exploration of Mars. Almost certainly within the next thirty years, a human crew will brave the isolation, the radiation, and the lack of gravity to walk on and explore the Red planet. However, because the mission distances and duration will be hundreds of times greater than the lunar missions, a human crew will face much greater obstacles and a higher risk than those experienced during the Apollo program. A single solution to many of these obstacles is to dramatically decrease the mission duration by developing a high performance propulsion system. The gas-core nuclear rocket (GCNR) has the potential to be such a system. The authors have completed a comparative study of the potential impact that a GCNR could have on a manned Mars mission. The total IMLEO, transit times, and accumulated radiation dose to the crew will be compared with the NASA Design Reference Missions.
Date: December 31, 1998
Creator: Howe, S.D.; DeVolder, B.; Thode, L. & Zerkle, D.
Partner: UNT Libraries Government Documents Department