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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Synergistic use of high and low thrust propulsion systems for piloted missions to Mars

The use of high-thrust, relatively-low-specific-impulse systems, such as chemical or nuclear thermal propulsion, in conjunction with low thrust, high-specific-impulse nuclear electric propulsion (NEP), has been considered for a representative piloted Mars mission. It is concluded that the single-burn option in an all-propulsive mission scenario does not yield a significant performance advantage in reduced trip time for reasonable masses. The multiple burn option allows significant reductions in trip time relative to the NEP system, and may provide a performance advantage over nuclear thermal propulsion depending upon the system assumptions. The combined systems serve to reduce NEP power requirements for fast trip times, and to reduce high thrust systems' sensitivity to mission opportunity. It is considered that 5 kg/kWe systems can provide significant improvements in mass and trip time over the single systems at power levels of 5 to 10 MWe.

Gilland, James H.↗
NASA NTRS1972

Planetary exploration with electrically propelled vehicles.

The characteristics of propulsion systems required for carrying out flight missions within the solar system, as desired by planetary physicists and astronomers, are reviewed. It is shown that an encouraging answer to these requirements is available in the form of electrostatic or ion propulsion systems. The design and performance characteristics of an electrostatic thrustor employing an ion source, accelerating electrode, beam neutralizer, and power source are discussed, together with those of the Kaufmann engine (electrostatic thrustor employing bombardment type ionization). More demanding missions which will become feasible with the advent of nuclear-electric power sources (such as the incore thermionic reactor) may include close orbiters around all the planets, and asteroid and cometary missions.

Stuhlinger, E.↗
NASA NTRS1993

Progress report on nuclear propulsion for space exploration and science

NASA is continuing its work in cooperation with the Department of Energy (DOE) on nuclear propulsion - both nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP). The focus of the NTP studies remains on piloted and cargo missions to Mars (with precursor missions to the moon) although studies are under way to examine the potential uses of NTP for science missions. The focus of the NEP studies has shifted to space science missions with consideration of combining a science mission with an earlier demonstration of NEP using the SP-100 space nuclear reactor power system. Both NTP and NEP efforts are continuing in 1993 to provide a good foundation for science and exploration planners. Both NTP and NEP provide a very important transportation resource and in a number of cases enable missions that could not otherwise be accomplished.

Bennett, Gary L.↗
NASA NTRSDate not supplied

Application of Analytical Hierarchy Process for Narrowing Down Nep Candidate Reactor Designs

NASA is currently studying the possibility of human exploration of Mars in the late 2030s timeframe using a hybrid nuclear electric propulsion (NEP)/chemical propulsion system. Present analyses indicate such a mission could require a reactor power system in the range of 2 to 6 MWe operating for approximately 3 years. At present, the Technology Readiness Levels (TRL) of key NEP technologies are still low, implying that significant technology development activities must be undertaken prior to making informed design selections for an integrated propulsion system. NASA’s Space Nuclear Propulsion (SNP) project has recently undertaken an in-depth effort to identify NEP candidate technologies and determine the required developmental work to mature these technologies to the point where they could realistically support the design and assembly of a full NEP system. A version of the Analytical Hierarchy Process is being employed to narrow the technology candidates for SNP investment planning. This multi-attribute decision-making process relies on quantified technical inputs and the judgement of Subject Matter Experts (SMEs) to evaluate technology options against key technical and programmatic Figures-of-Merit (FOM) at the subsystem and optimized system level. The process and an example evaluation of nuclear fuel/moderator combinations in a sodium heat pipe honeycomb-geometry reactor concept are described. The evaluation and analysis methodology described in this paper can be employed for pairwise comparisons between reactor concepts and technology choices as new data become available.

Dasari V Rao↗
NASA NTRS2013

Estimating the Effects of Astronaut Career Ionizing Radiation Dose Limits on Manned Interplanetary Flight Programs

The Hybrid Inflatable DSH combined with electric propulsion and high power solar-electric power systems offer a near TRL-now solution to the space radiation crew dose problem that is an inevitable aspect of long term manned interplanetary flight. Spreading program development and launch costs over several years can lead to a spending plan that fits with NASA's current and future budgetary limitations, enabling early manned interplanetary operations with space radiation dose control, in the near future while biomedical research, nuclear electric propulsion and active shielding research and development proceed in parallel. Furthermore, future work should encompass laboratory validation of HZETRN calculations, as previous laboratory investigations have not considered large shielding thicknesses and the calculations presented at these thicknesses are currently performed via extrapolation.

Koontz, Steven L.↗
NASA NTRS1985

Ion propulsion technology requirements for planetary mission applications

Integrating a clustered, four engine ion propulsion system to the Mariner Mark II spacecraft is shown to reduce total trip time for the five proposed Mariner Mark II missions by fifteen years. In addition, this advanced Solar Electric Propulsion (SEP) system enables rendezvous encounters with five main belt asteroids rather than one. A precursor Advanced Capability Explorer (ACE) technology demonstration vehicle is proposed to investigate SEP spacecraft interaction and control requirements in support of these future mission opportunities. It is shown that the ACE spacecraft could be assembled from existing residual hardware, protoflight equipment and commercially available flight tested components. The ion propulsion system requirements to support ambitious Nuclear Electric Propulsion (NEP) missions are also examined and specific technology development objectives presented.

Aston, G.↗
NASA NTRS1993

The 20 kWe NEP flight system

A low-power, near-term nuclear electric propulsion (NEP) system was proposed as a useful interim system for near-term space exploration. Although the ultimate goal of a 100 kWe class, low specific mass for planetary exploration remains, application of the technologies that are currently mature to earlier missions of interest has grown at the higher levels of NASA. In response to this interest, a study of low-power system and mission options was initiated, with the Nuclear Propulsion Office serving to coordinate system activities. A nominal 20 kWe system using Brayton power conversion was selected by the joint NASA/DOE Space Nuclear Power and Propulsion team; however, other power levels and system options will be considered. NASA's Office of Space Science and Applications has expressed interest in exploiting NEP's mission capabilities, both in the near-term and for more difficult, later missions. Technologies considered mature for this type of system are the SP-100 reactor, Brayton dynamic power conversion, and 30 cm ion thrusters, all of which have extensive ground demonstration backgrounds.

Gilland, Jim↗
NASA NTRS1991

Solar electric propulsion cargo spacecraft for Mars missions

One of the topics available to the 1990-91 Aerospace Engineering senior class was the development of a preliminary design of an unmanned cargo ferry that would support the Mars mission by bringing equipment and supplies from a low Earth orbit (LEO) to a low Mars orbit (LMO). Several previous studies initiated by NASA have indicated that low-thrust transportation systems seem to offer the best performance for Mars missions. Such systems are characterized by long spiral times during escape and capture maneuvers, high payload mass fractions, and, typically, low propellant mass fractions. Of two main low-thrust candidates, nuclear electric propulsion (NEP) and solar electric propulsion (SEP), only the first one received extensive consideration because it seemed to represent the most promising concept for a manned mission to Mars. However, any sustained Mars initiative will have to include an unmanned cargo transportation system, for which an SEP concept deserves very careful consideration. The key assumptions and requirements established in cooperation with the Space Exploration Initiative office at the NASA Langley Research Center were (1) vehicle is assembled at the Space Station Freedom (SSF); (2) Earth-to-orbit delivery of the vehicle components, propellant, and payload is via shuttle-C; (3) vehicle's cargo mass is 61,000 kg; (4) vehicle delivers cargo to LMO at an altitude of 500 km and inclination of 70 deg; (5) vehicle returns (without cargo) to SSF; (6) vehicle should be reusable for at least three missions; and (7) vehicle is powered by ion argon thrusters. Two configurations were developed by two student teams, working mostly independently.

Source record↗
NASA NTRS2006

Evaluation of High-Power Solar Electric Propulsion using Advanced Ion, Hall, MPD, and PIT Thrusters for Lunar and Mars Cargo Missions

This paper presents the results of mission analyses that expose the advantages and disadvantages of high-power (MWe-class) Solar Electric Propulsion (SEP) for Lunar and Mars Cargo missions that would support human exploration of the Moon and Mars. In these analyses, we consider SEP systems using advanced Ion thrusters (the Xenon [Xe] propellant Herakles), Hall thrusters (the Bismuth [Bi] propellant Very High Isp Thruster with Anode Layer [VHITAL], magnetoplasmadynamic (MPD) thrusters (the Lithium [Li] propellant Advanced Lithium-Fed, Applied-field Lorentz Force Accelerator (ALFA2), and pulsed inductive thruster (PIT) (the Ammonia [NH3] propellant Nuclear-PIT [NuPIT]). The analyses include comparison of the advanced-technology propulsion systems (VHITAL, ALFA2, and NuPIT) relative to state-of-theart Ion (Herakles) propulsion systems and quantify the unique benefits of the various technology options such as high power-per-thruster (and/or high power-per-thruster packaging volume), high specific impulse (Isp), high-efficiency, and tankage mass (e.g., low tankage mass due to the high density of bismuth propellant). This work is based on similar analyses for Nuclear Electric Propulsion (NEP) systems.

Lunar cargo↗
NASA NTRSDate not supplied

Affordable Development Strategy for NEP Nuclear Systems

One nuclear electric propulsion (NEP) reactor systems under consideration is a hydride moderated thermal spectrum reactor fueled by high assay low enriched uranium (HALEU). While such a reactor is expected to yield the lightest HALEU reactor design, its development challenges grow exponentially with increasing mission demands, most notably power output, specific weight of the overall system (which may require operation at temperatures exceeding 1200 K), service lifetime, and human-rated reliability. Two of the greatest cost drivers are full-powered nuclear demonstrations and extensive material development campaigns, so it is important to consider options that can minimize the need for or complexity of such tasks. This paper discusses a structured framework being developed for assessing how NEP design choices, such as materials selection, neutronic features, and heat-removal technologies, can translate into project risk and how project performance goals can be traded with development cost.Reactors operating at high temperatures often require cutting-edge heat transfer technologies and creep-resistant materials. Use of new materials in high temperature reactors brings additional complication beyond those common to any new space materials development campaign. For example, such materials may not possess necessary neutronic cross-sectional or neutronic irradiation data. Similarly, use of new materials may significantly influence core neutronics; in some extreme cases, neutronic reactivity feed-back of certain new materials can vary during their service life as radiation damage impacts the scattering cross-section. In an affordable development approach, high fidelity modeling and simulation tools are used to identify and characterize potential ‘knees-in-the-curves’ in the relationship that exists between the mission characteristics and the project risk. Of particular significance is use of modern uncertainty management and variance reduction methods to perform gap analyses that feed into phenomena identification and ranking tables (PIRT) commonly used to communicate nuclear readiness levels. Model-based measurements techniques are used to design sub-scale experiments as a substitute to minimize orcompletely eliminate the need for nuclear demonstrations.This paper will describe the approach and present preliminary results. It will lay the groundwork for developing a set of metrics that can be broadly characterized as system nuclear readiness levels and advancement degree of difficulty for nuclear systems. Equally importantly, a goal of this paper is to initiate a dialogue among stakeholders on what is the sufficient level of maturity that is required for launching a demonstration unit.

Dasari V Rao↗
NASA NTRS1990

Enhancing space transportation: The NASA program to develop electric propulsion

The NASA Office of Aeronautics, Exploration, and Technology (OAET) supports a research and technology (R and T) program in electric propulsion to provide the basis for increased performance and life of electric thruster systems which can have a major impact on space system performance, including orbital transfer, stationkeeping, and planetary exploration. The program is oriented toward providing high-performance options that will be applicable to a broad range of near-term and far-term missions and vehicles. The program, which is being conducted through the Jet Propulsion Laboratory (JPL) and Lewis Research Center (LeRC) includes research on resistojet, arcjets, ion engines, magnetoplasmadynamic (MPD) thrusters, and electrodeless thrusters. Planning is also under way for nuclear electric propulsion (NEP) as part of the Space Exploration Initiative (SEI).

Bennett, Gary L.↗
NASA NTRS1987

TAU - A mission to a thousand astronomical units

The potential of nuclear electric propulsion (NEP) is investigated as the enabling technology for achieving a mission to a thousand astronomical units within 50 years duration. By means of a 1000 AU baseline, the primary objective is to make measurements of distances to the stars in the Galaxy and beyond. In addition, several deep space unique studies in astronomy, astrophysics, cosmology, and space plasma physics can be carried out. NEP technology requirements for a mission to 1000 AU are addressed. These technology requirements are compared with current plans for both nuclear space power and ion propulsion research. And finally an example TAU spacecraft system is described.

Nock, K. T.↗
NASA NTRSDate not supplied

Fabrication and Mechanical Testing of Heat Exchanger Tubes for Nuclear Propulsion and Other Applications from Continuous Carbon Nanotube Yarns and Tapes

As NASA and other agencies are looking to conduct sustained operations in space, nuclear engines have been receiving increased focus. The high specific impulse and high fuel efficiency at high thrust output of these engines can halve the transit time for human missions to Mars, or enable missions requiring multiple orbital parameter adjustments. In both Nuclear Thermal Propulsion (NTP) and Nuclear Electric Propulsion (NEP) systems, heat exchangers play a critical role in transferring energy from the reactor to a working fluid, hydrogen in the case of NTP and a molten salt or other fluid for electricity generation in NEP. Heat exchangers are also required in other parts of the spacecraft. Various manufacturing methods and materials are being considered for the heat exchangers. In this presentation the fabrication and testing of heat exchangers made from continuous carbon nanotube (CNT) yarns and tapes are discussed. The fabrication workflow is compared and contrasted, as well as performance of prototype heat exchanger tubes fabricated using the various CNT formats. The failure loads and mechanisms of the tubes under tensile, compression, and bending loads are assessed. A further comparison of the CNT materials to components fabricated from carbon fiber is made. The presented work will contribute to the selection of approaches for heat exchanger fabrication methods for nuclear propulsion and other applications.

Heat Exchanger↗
NASA NTRS2001

Space Fission Propulsion System Development Status

The world's first man-made self-sustaining fission reaction was achieved in 1942. Since then fission has been used to propel submarines, generate tremendous amounts of electricity, produce medical isotopes, and provide numerous other benefits to society. Fission systems operate independently of solar proximity or orientation, and are thus well suited for deep space or planetary surface missions. In addition, the fuel for fission systems (enriched uranium) is virtually non-radioactive. The primary safety issue with fission systems is avoiding inadvertent system start. Addressing this issue through proper system design is straight-forward. Despite the relative simplicity and tremendous potential of space fission systems, the development and utilization of these systems has proven elusive. The first use of fission technology in space occurred 3 April 1965 with the US launch of the SNAP-10A reactor. There have been no additional US uses of space fission systems. While space fission systems were used extensively by the former Soviet Union, their application was limited to earth-orbital missions. Early space fission systems must be safely and affordably utilized if we are to reap the benefits of advanced space fission systems. NASA's Marshall Space Flight Center, working with Los Alamos National Laboratory (LANL), Sandia National Laboratories, and others, has conducted preliminary research related to a Safe Affordable Fission Engine (SAFE). An unfueled core has been fabricated by LANL, and resistance heaters used to verify predicted core thermal performance by closely mimicking heat from fission. The core is designed to use only established nuclear technology and be highly testable. In FY01 an energy conversion system and thruster will be coupled to the core, resulting in an 'end-to-end' nuclear electric propulsion demonstrator being tested using resistance heaters to closely mimic heat from fission. Results of the SAFE test program will be presented. The applicability of a SAFE-powered electric propulsion system to outer planet science missions will also be discussed.

Houts, M.↗
NASA NTRS1996

Investigation of Natural and Man-Made Radiation Effects on Crews on Long Duration Space Missions

Over the past several years, NASA has studied a variety of mission scenarios designed to establish a permanent human presence on the surface of Mars. Nuclear electric propulsion (NEP) is one of the possible elements in this program. During the initial stages of vehicle design work, careful consideration must be given to not only the shielding requirements of natural space radiation, but to the shielding and configuration requirements of the on-board reactors. In this work, the radiation transport code MCNP has been used to make initial estimates of crew exposures to reactor radiation fields for a specific manned NEP vehicle design. In this design, three 25 MW(sub th), scaled SP-100-class reactors are shielded by three identical shields. Each shield has layers of beryllium, tungsten, and lithium hydride between the reactor and the crew compartment. Separate calculations are made of both the exiting neutron and gamma fluxes from the reactors during beginning-of-life, full-power operation. This data is then used as the source terms for particle transport in MCNP. The total gamma and neutron fluxes exiting the reactor shields are recorded and separate transport calculations are then performed for a 10 g/sq cm crew compartment aluminum thickness. Estimates of crew exposures have been assessed for various thicknesses of the shield tungsten and lithium hydride layers. A minimal tungsten thickness of 20 cm is required to shield the reactor photons below the 0.05 Sv/y man-made radiation limit. In addition to a 20-cm thick tungsten layer, a 40-cm thick lithium hydride layer is required to shield the reactor neutrons below the annual limit. If the tungsten layer is 30-cm thick, the lithium hydride layer should be at least 30-cm thick. These estimates do not take into account the photons generated by neutron interactions inside the shield because the MCNP neutron cross sections did not allow reliable estimates of photon production in these materials. These results, along with natural space radiation shielding estimates calculated by NASA Langley Research Center, have been used to provide preliminary input data into a new Macintosh-based software tool. A skeletal version of this tool being developed will allow rapid radiation exposure and risk analyses to be performed on a variety of Lunar and Mars missions utilizing nuclear-powered vehicles.

Bolch, Wesley E.↗