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NASA NTRS1993

MeV ion-beam analysis of optical data storage films

Our objectives are threefold: (1) to accurately characterize optical data storage films by MeV ion-beam analysis (IBA) for ODSC collaborators; (2) to develop new and/or improved analysis techniques; and (3) to expand the capabilities of the IBA facility itself. Using H-1(+), He-4(+), and N-15(++) ion beams in the 1.5 MeV to 10 MeV energy range from a 5.5 MV Van de Graaff accelerator, film thickness (in atoms/sq cm), stoichiometry, impurity concentration profiles, and crystalline structure were determined by Rutherford backscattering (RBS), high-energy backscattering, channeling, nuclear reaction analysis (NRA) and proton induced X-ray emission (PIXE). Most of these techniques are discussed in detail in the ODSC Annual Report (February 17, 1987), p. 74. The PIXE technique is briefly discussed in the ODSC Annual Report (March 15, 1991), p. 23.

Leavitt, J. A.↗

NASA NTRS2008

The Bess Investigation of the Origin of Cosmic-ray Antiprotons and Search for Cosmological Antimatter

The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) collaboration has made precise measurements of the spectra of cosmic ray antiprotons and light nuclei and conducted a sensitive search for antinuclei. Ten BESS high-latitude flights, eight from Canada and two from Antarctica, span more than a Solar cycle between 1993 and 2007/2008. BESS measurements of low-energy antiprotons constrain candidate models for dark matter including the possible signature of primordial black hole evaporation. The stringent BESS measurements of antiprotons and the elemental and isotopic spectra of H and He provide strong constraints on models of cosmic-ray transport in the Galaxy and Solar System. BESS has also reported the first antideuterium upper limit. BESS employs a superconducting magnetic-rigity spectrometer with time-of-flight and aerogel Cherenkov detectors to identify incident particles by charge, charge sign, mass, and energy. The BESS-Polar long-duration instrument has reduced lower energy limit of 100 MeV (top of the atmosphere) to increase its sensitivity to possible primary antiproton sources. BESS-Polar II was rebuilt with extended magnet lifetime, improved detector and electronic performance, and greater data storage capacity. It was flown fro Antarctica December 2007-January 2008, recording about 4.6 bission events during 24.5 days at float altitude with the magnet on. During the flight the influence of a high-speed stream in the Solar wind was observed. Details of the BESS-Polar II instrument and flight performance are reported elsewhere at this conference. The successful BESS-Polar II flight at Solar minimum is especially important. Most cosmic-ray antiprotons are secondary products of nuclear interactions of primary cosmic-ray nuclei with the interstellar gas, giving a spectrum that peaks at about 2 GeV and falls rapidly to higher and lower energies. However, BESS data taken in the previous Solar minimum show a small excess over secondary expectations at low energies, possibly suggesting the presence of an additional component that may be masked at higher levels of Solar modulation. The high-statistics Solar minimum data obtained by BESS-Polar II will provide a difinitive test of this component. We will review the BESS program and report the latest results including the antiproton and proton spectra measured in the BESS-Polar I flight, the search for cosmic antinuclei, and the status of the BESS-Polar II analysis.

Mitchell, John↗

NASA NTRSDate not supplied

Lunar Water Pilot Plant Conceptual Design

A study was conducted to determine mass, power, and concept of operations for a polar water pilot plant that can produce 1000 kg of oxygen in a year from 1125 kg of water extracted from the icy regolith in a permanently shadowed region(PSR). Icy regolith in the PSR is excavated and delivered to a stationary dryer that extracts the water which is frozen in an ice tanker and delivered up to the ridge for further processing into oxygen and hydrogen. This study assumed a previously landed nuclear reactor was available in the PSR to provide power for the water extraction, which requires 2.4 kW of power, including a 30 percent margin. At 325 kg, the ISRU system massin the PSR, including the excavator, should be deliverable by one of the Commercial Lunar Payload Services (CLPS) landers, and the packaging and concept of operations are shown using one specific CLPS lander. The mass and power of the ISRU system components on the ridge for water electrolysis and liquefaction and storage of the oxygen and hydrogen are estimated at 840 kg and 4.3 kW.

Lunar↗

NASA NTRS1986

Alternative power generation concepts for space

Trade and optimization studies that highlight the potential of solar and nuclear dynamic systems relative to photovoltaic power systems are summarized. The solar dynamic case is the LEO Stirling system, while the nuclear system is the SP-100 system goal. Nuclear systems have the potential for the lightest weight, least area, sunlight independent, radiation-durable system. Solar dynamic systems pose a stiff challenge to photovoltaic systems in the midaltitudes because of their insensitivity to the Van Allen radiation belts. While the initial operational capability space station power system is only slightly superior to the SOA PV system, with development focused on the key technologies, advanced solar dynamic systems are fully competitive in LEO midaltitudes with the advanced photovoltaic systems. Advances in energy storage systems (100 Whrs/kg required) are essential.

Brandhorst, Henry W., Jr.↗

NASA NTRSDate not supplied

Lunar Water Pilot Plant Conceptual Design

A study was conducted to determine mass, power, and concept of operations for a polar water pilot plant that can produce 1000 kg of oxygen in a year from 1125 kg of water extracted from the icy regolith in a permanently shadowed region(PSR). Icy regolith in the PSR is excavated and delivered to a stationary dryer that extracts the water which is frozen in an ice tanker and delivered up to the ridge for further processing into oxygen and hydrogen. This study assumed a previously landed nuclear reactor was available in the PSR to provide power for the water extraction, which requires 2.4 kW of power, including a 30 percent margin. At 325 kg, the ISRU system mass in the PSR, including the excavator, should be deliverable by one of the Commercial Lunar Payload Services (CLPS) landers, and the packaging and concept of operations are shown using one specific CLPS lander. The mass and power of the ISRU system components on the ridge for water electrolysis and liquefaction and storage of the oxygen and hydrogen are estimated at 840 kg and 4.3 kW.

Lunar↗

NASA NTRS1972

Power and energy for posterity

The use of sophisticated space energy generation and storage systems to benefit the general public was examined. The utilization of these systems for pollution-free generation of energy to satisfy mankind's future electrical, thermal, and propulsion needs was of primary concern. Ground, air, and space transportation; commercial, peaking, and emergency electrical power; and metropolitan and unit thermal energy requirements were considered. Each type of energy system was first analyzed in terms of its utility in satisfying the requirement, and then its potential in reducing the air, noise, thermal, water, and nuclear pollution from future electrical and thermal systems was determined.

Barthelemy, R. F.↗

NASA NTRS2024

Xplo-SA9T: Optimization of Sorbent Technology With Existing and New Amine Variants for Carbon Dioxide Removal and Humidity Control

Scrubbing of the spacesuit air stream to control humidity and regulate carbon dioxide (CO 2 ) relies on amine-loaded resins, colloquially known as sorbents. The efficacy of Rapid Cycle Amine technology relies on the propensity of nitrogens toward adsorption of CO 2 while simultaneously offering regenerative properties under vacuum or positive pressure. The commonly utilized sorbent, SA9T, was recreated and evaluated further to increase stability and serve as a benchmark comparison for newly synthesized amine sorbent technologies. Ongoing storage studies with eight different environments will allow the development of applicable storage protocols and provide insight into possible ammonia generation pathways. Attempts to alleviate the known issues with SA9T included the alteration of the primary amine (tetraethylenepentamine), the choice of resin, and the particle size distribution. In-house CO 2 breakthrough experiments were conducted using a specialized apparatus that can simulate spacesuit conditions, offering high-quality triplicate capacity analysis affording direct comparison to known adsorbents in the literature. Thermo-Desorption Gas Chromatography Mass Spectrometry studies on the synthesized materials revealed any reagent or solvent offgassing while Nuclear Magnetic Resonance spectroscopy tracked the stability of the bound amine. Scanning Electron Microscope images of sieved materials provided a more accurate size interpretation facilitating synthetic design and pressure drop elimination. All efficient sorbents were synthesized to a commercial batch scale subsequent to evaluation including Xplo-SA9T.

John R Tidwell↗

NASA NTRS1986

Post-perihelion brightening of Halley's Comet: A case of nuclear summer

Increased brightness and gas production rates for Halley's comet after perihelion are explained as a result of seasonal effects on an obliquely rotating nucleus. The highly eccentric cometary orbit causes a rapid change in solar declination as the comet rounds perihelion, resulting in drastic changes in the insolation reaching the Northern and Southern Hemispheres of the nucleus. The rapid heating of the Northern Hemisphere post-perihelion likely results in substantial cracking of the non-volatile surface crust due to thermal stresses, exposing areas of fresh volatile ices. The orientation of the triaxial ellipsoid nucleus may also play a role in exposing more surface area to continuous sunlight and sublimation after perihelion. Post-perihelion brightening models based on heat flow and storage in sub-surface layers of the nucleus pre-perihelion are likely not viable because of the low thermal conductivities of porous, low density cometary surface materials.

Weissman, Paul R.↗

NASA NTRS1995

SPE(R)-OBOGS: On-board oxygen generating sustem

Regulations require oxygen usage by commercial airline flight crews during check out and during certain aircraft configurations. This oxygen is drawn from a high pressure onboard pressure cylinder storage system. In a typical aircraft oxygen cylinder removal for oxygen ground servicing is conducted every 4 to 6 weeks. An on board oxygen generating system has been developed to eliminate the need for oxygen ground servicing. The SPE-OBOGS supplies oxygen during flight in a 'trickle charge' mode to replenish the consumed oxygen at pressures up to 1850 psi. The Electrochemical cell stack is the fundamental SPE-OBOGS system component. The same basic proton exchange membrane technology, previously used for the Gemini program fuel cells and currently used in nuclear submarines as oxygen generators, is used in the SPE-OBOGS. An in-serivce evaluation of the SPE-OBOGS is in the planning stage and a zero gravity version is being promoted for on orbit space suit oxygen system recharge. Summary results of the SPE-OBOGS development will be addressed.

Mcelroy, J.↗

NASA NTRS1985

An Innovation for the Energy Industry

REDOX is an economical energy storage system which promises major reductions in the cost of storing electrical energy. The system is based upon the conversion of chemical energy into electrical energy. 75 percent of the energy used to charge the system is returned. It is flexible and the energy may be stored for long periods. It was developed by Lewis Research Center, who transferred the technology to SOHIO for further development and possible commercialization. Redox could eliminate the use of high quality generator levels and would be particularly valuable to utilities which generate power from coal or nuclear energy.

Source record↗

NASA NTRS1987

On the theory of type I X-ray bursts - The energetics of bursts and the nuclear fuel reservoir in the envelope

A comparison is made between the observed properties of type I X-ray bursts from 4U/MXB 1636-53 and those of models of thermonuclear flashes on accreting neutron stars. Possible explanations of variations in the burst recurrence properties without an apparent correlation with accretion rate are discussed. The strongest bursts with photospheric expansion are described well by current spherically symmetric models. The observed weak bursts suggest a mechanism that can promote the inward propagation and heating of accreted fuel so as to give rise to thermonuclear runaways much earlier than expected from spherical models. A sufficient amount of fuel to feed the weak bursts can be stored in the outer layers for neutron stars with radii greater than 8 km. The proposed mechanism and fuel storage can resolve the longstanding problem of bursts in rapid succession with intervals shorter than about 10 minutes. The proposed model explains the variation of burst peak fluxes observed from 4U/MSB 1636-53.

Fujimoto, Masayuki Y.↗

NASA NTRS1991

SPE (tm) water electrolyzers in support of mission from planet Earth

During the 1970's, the Solid Polymer Electrolyte (SPE) water electrolyzer, which uses ion exchange membranes as its sole electrolyte, was developed for nuclear submarine metabolic oxygen production. SPE water electrolyzer developments included operation at up to 3,000 psia and at current densities in excess of 1,000 amps per square foot. The SPE water electrolyzer system has accumulated tens of thousands of system hours with the Navies of both the United States and the United Kingdom. During the 1980's, the basic SPE water electrolyzer cell structure developed for the Navies was incorporated into several demonstrators for NASA's Space Station Program. Among these were: (1) the SPE regenerative fuel cell for electrical energy storage; (2) the SPE water electrolyzer for metabolic oxygen production; and (3) the high pressure SPE water electrolyzer for reboost propellant production. In the 1990's, emphasis will be the development of SPE water electrolyzers for Mission from Planet Earth. Currently defined potential applications for the SPE water electrolyzer include: (1) SPE water electrolyzers operating at high pressure as part of a regenerative fuel cell extraterrestrial surface energy storage system; (2) SPE water electrolyzers for propellant production from extraterrestrial indigenous materials; and (3) SPE water electrolyzers for metabolic oxygen and potable water production from reclaimed water.

J F McElroy↗

NASA NTRS1992

SPE water electrolyzers in support of the lunar outpost

During the 1970s, the SPE water electrolyzer, which uses ion exchange membranes as its sole electrolyte, was developed for nuclear submarine metabolic oxygen production. These developments included SPE water electrolyzer operation at up to 3,000 psia and at current densities in excess of 1,000 amps per square foot. The SPE water electrolyzer system is now fully qualified for both the U.S. and U.K. Navies with tens of thousands of system hours accumulated at sea. During the 1980s, the basic SPE water electrolyzer cell structure developed for the Navies was incorporated into several demonstrations for NASA's Space Station Program. Among these were: the SPE regenerative fuel cell for electrical energy storage; the SPE water electrolyzer for metabolic oxygen production; and the high pressure SPE water electrolyzer for reboost propulsion reactant production. In the 1990s, one emphasis will be the development of SPE water electrolyzers for the Lunar Outposts Currently defined potential Lunar Outpost applications for the SPE water electrolyzer include: SPE water electrolyzers for metabolic oxygen and potable water production from reclaimed water; and SPE water electrolyzers operating at high pressure as part of stationary and mobile surface energy storage systems.

Mcelroy, J. F.↗

NASA NTRS1976

Pulsed thermionic converter study

A nuclear electric propulsion concept using a thermionic reactor inductively coupled to a magnetoplasmadynamic accelerator (MPD arc jet) is described, and the results of preliminary analyses are presented. In this system, the MPD thruster operates intermittently at higher voltages and power levels than the thermionic generating unit. A typical thrust pulse from the MPD arc jet is characterized by power levels of 1 to 4 MWe, a duration of 1 msec, and a duty cycle of approximately 20%. The thermionic generating unit operates continuously but with a lower power level of approximately 0.4 MWe. Energy storage between thrust pulses is provided by building up a large current in an inductor using the output of the thermionic converter array. Periodically, the charging current is interrupted, and the energy stored in the magnetic field of the inductor is utilized for a short duration thrust pulse. The results of the preliminary analysis show that a coupling effectiveness of approximately 85 to 90% is feasible for a nominal 400 KWe system with an inductive unit suitable for a flight vehicle.

Source record↗

NASA NTRS1975

Helium heater design for the helium direct cycle component test facility

The paper describes a helium heater to be used to conduct non-nuclear demonstration tests of the complete power conversion loop for a direct-cycle gas-cooled nuclear reactor power plant. Requirements for the heater include: heating the helium to a 1500 F temperature, operating at a 1000 psia helium pressure, providing a thermal response capability and helium volume similar to that of the nuclear reactor, and a total heater system helium pressure drop of not more than 15 psi. The unique compact heater system design proposed consists of 18 heater modules; air preheaters, compressors, and compressor drive systems; an integral control system; piping; and auxiliary equipment. The heater modules incorporate the dual-concentric-tube 'Variflux' heat exchanger design which provides a controlled heat flux along the entire length of the tube element. The heater design as proposed will meet all system requirements. The heater uses pressurized combustion (50 psia) to provide intensive heat transfer, and to minimize furnace volume and heat storage mass.

Larson, V. R.↗

NASA NTRS1990

Neutron and gamma irradiation effects on power semiconductor switches

The performance characteristics of high power semiconductor switches subjected to high levels of neutron fluence and gamma dose must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect the electrical and switching characteristics of solid state power switches is discussed. The experimental measurement system and radiation facilities are described. Experimental data showing the effects of neutron and gamma irradiation on the performance characteristics are given for power-type NPN Bipolar Junction Transistors (BJTs), and Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs). BJTs show a rapid decrease in gain, blocking voltage, and storage time for neutron irradiation, and MOSFETs show a rapid decrease in the gate threshold voltage for gamma irradiation.

Schwarze, G. E.↗

NASA NTRS1990

Neutron and gamma irradiation effects on power semiconductor switches

The performance characteristics of high-power semiconductor switches subjected to high levels of neutron fluence and gamma dose must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect the electrical and switching characteristics of solid state power switches is discussed. The experimental measurement system and radiation facilities are described. Experimental data showing the effects of neutron and gamma irradiation on the performance characteristics are given for power-type NPN Bipolar Junction Transistors (BJTs), and Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs). BJTs show a rapid decrease in gain, blocking voltage, and storage time for neutron irradiation, and MOSFETs show a rapid decrease in the gate threshold voltage for gamma irradiation.

Schwarze, G. E.↗

NASA NTRS1999

Comets after Hyakutake and Hale-Bopp

Being icy, cometary nuclei are the most easily modified bodies in the solar system - even modest heating is sufficient to induce significant weight loss. This sublimative loss and longterm storage far from the sun protect the nucleus against internal warming and ensure that cometary nuclei today contain the least processed material remaining from the early nebula - or perhaps from the natal cloud. The chemical compositions of ices, low temperature-refractory organics, and refractory minerals (and their physical states) provide sensitive probes of the origin and history of this material. The fortunate appearance of Hyakutake and Hale-Bopp has provided a wealth of information on these Oort cloud comets, obtained with a wide range of astronomical approaches. I will review certain key results for these comets, such as chemical abundances, isotopic abundance ratios, nuclear spin statistics, and nuclear vs extended production of "parent volatiles", and will illustrate how these test the origins of cometary material. A comparison with 1P/Halley--a third comet from the giant planet nebular region--will be discussed in the context of heterogeneity among these bodies.

Mumma, Michael J.↗