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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

Life Support and Habitation Systems: Crew Support and Protection for Human Exploration Missions Beyond Low Earth Orbit

Life Support and Habitation Systems (LSHS) is one of 10 Foundational Domains as part of the National Aeronautics and Space Administration s proposed Enabling Technology Development and Demonstration (ETDD) Program. LSHS will develop and mature technologies to sustain life on long duration human missions beyond Low Earth Orbit that are reliable, have minimal logistics supply and increase self-sufficiency. For long duration exploration missions, further closure of life support systems is paramount, including focus on key technologies for atmosphere revitalization, water recovery, waste management, thermal control and crew accommodation that recover additional consumable mass, reduce requirements for power, volume, heat rejection, crew involvement, and which have increased reliability and capability. Other areas of focus include technologies for radiation protection, environmental monitoring and fire protection. Beyond LEO, return to Earth will be constrained. The potability of recycled water and purity of regenerated air must be measured and certified aboard the spacecraft. Missions must be able to recover from fire events through early detection, use of non-toxic suppression agents, and operation of recovery systems that protect on-board Environmental Control and Life Support (ECLS) hardware. Without the protection of the Earth s geomagnetic field, missions beyond LEO must have improved radiation shielding and dosimetry, as well as warning systems to protect the crew against solar particle events. This paper will describe plans for the new LSHS Foundational Domain and mission factors that will shape its technology development portfolio.

Barta, Daniel J.↗
NASA NTRS2024

Commercial Crew Program (CCP) Post-flight Reference Radiation Environments

The Nowcast of Aerospace Ionizing RAdiation System (NAIRAS) model version 3 is a coupled physics-based model that transports ionizing radiation through the heliosphere, Earth’s magnetosphere, the neutral atmosphere, and aircraft and spacecraft shielding. Ionizing radiation sources included in the model are: 1) galactic cosmic rays, 2) solar energetic particles including protons and heavy ions, and 3) the inner radiation belt trapped protons and electrons. NAIRAS predicts dosimetric quantities and differential and integral flux and fluence quantities for assessing human radiation exposure and single event effects in vehicle electronic systems from the Earth’s surface to the space environment.

Christopher J Mertens↗
NASA NTRS2023

NAIRAS Ionizing Radiation Model: Extension from Atmosphere to Space

The Nowcast of Aerospace Ionizing RAdiation System (NAIRAS) model is a real-time, global, physics-based model originally developed to predict exposure from cosmic radiation to air travelers from both galactic and solar sources. A prototype operational NAIRAS model has provided tabular and graphical data products via its public web site for about ten years. A new version of the NAIRAS model has been developed that incorporates an extension of the model domain from the atmospheric ionizing radiation environment to the space radiation environment, with the addition of the trapped inner belt proton source and altitude-dependent and rigidity-dependent geomagnetic shielding of the galactic cosmic rays (GCR) and solar energetic particle (SEP) protons. New output products of differential and integral particle flux have been developed for the characterization of single-event effects (SEE), expanding the application of NAIRAS from human radiation exposure assessment to allowing end-users to quantify radiation environment risks to aviation and spacecraft microelectronic systems. The NAIRAS model has transitioned to prototype operations at the Community Coordinated Modeling Center (CCMC) where the model now operates in two modes: (1) real-time global predictions of the atmospheric radiation environment and (2) a run-on-request (RoR) service allowing the user to select a specific time period for the global dosimetric calculations, or to upload an aircraft, balloon, or spaceflight trajectory file to provide predictions of the dosimetric and particle flux quantities along the flight path. The new features of NAIRAS version 3.0 are described in this paper and example results of the new output products for low-Earth orbit (LEO), medium-Earth orbit (MEO), and free-space radiation environments are presented

Christopher J. Mertens↗
NASA NTRS2024

Passively Cooled Superconductors in Space

The objective of this project was to determine to what extent (as a function of distance from the Sun) our “Solar White” coatings could passively chill a high temperature superconductor (HTS) and maintain it in a superconducting state. The end goal is to enable the use of superconductors in space for active radiation shielding and highly efficient energy storage and retrieval. The best we were able to demonstrate during this testing was a coating with a solar absorptivity of 2.6%, which is sufficient to keep the superconductor we chose cold enough for these purposes at distances of 1.25 astronomical units (AU) from the Sun. Computations and modeling show that we would need samples with solar absorptivities of less than 1.5% for 1 AU and beyond operation. Our best tile to date was measured as having 1% absorption, which is still an order of magnitude higher than our theoretical limit. This should be achievable once manufacturing consistency is achieved. We are in the process of commercializing production of Solar White, and are hopeful that more consistent and improved results will be achieved within the coming year.

Mark Nurge↗
NASA NTRS2001

HZETRN: neutron and proton production in quasi-elastic scattering of GCR heavy-ions

The development of transport models for radiation shielding design and evaluation has provided a series of deterministic computer codes that describe galactic cosmic radiation (GCR), solar particle events, and experimental beams at particle accelerators. These codes continue to be modified to accommodate new theory and improvements to the particle interaction database (Cucinotta et al., 1994, NASA Technical Paper 3472, US Government Printing Office, Washington DC). The solution employed by the heavy-ion transport code HZETRN was derived with the assumption that nuclear fragments are emitted with the same velocity as the incident ion through velocity conserving nuclear interactions. This paper presents a version of the HZETRN transport code that provides a more realistic distribution of the energy of protons and neutrons emitted from GCR interactions in shields. This study shows that the expected GCR dose equivalent is lower than previously calculated for water shields that are less than 110 g cm-2 thick. Calculations of neutron energy spectra in low Earth orbit indicate substantial contributions from relativistic neutrons. c2001 Elsevier Science Ltd. All rights reseved.

NASA Center LaRC↗
NASA NTRS2016

Fabrication of Regolith-Derived Radiation Shields: Preliminary Results

Unlike the Earth, Mars and asteroids do not have a magnetosphere to protect humans, mechanisms and electronics from damaging Galactic Cosmic Radiation (GCR) and solar particle events (SPE). This presents one of the highest risks to crew and onboard electronics during interplanetary journeys. The goal of this project is to evaluate the effectiveness of carbonaceous asteroids and other hydrogen-rich materials as potential radiation shielding materials, which ultimately could be tested during planned crewed missions to a captured asteroid fragment (ARM). This type of investigation represents an initial effort to develop radiation shield material compositions, production methods and technologies, and optimization methodology for manufacturing radiation shields in deep space for large exploration human missions or by emerging new industries seeking to stage their spacecraft for the exploitation of the resources of asteroids. Carbonaceous chondrites (C-type) are of particular interest as sources of compounds such as water ice and hydrogen-rich carbon molecules, which can provide sufficient low Z element density to provide radiation protection at adequate shield thicknesses.

Regolith↗
NASA NTRS2012

Observations of Carbon Isotopic Fractionation in Interstellar Formaldehyde

Primitive Solar System materials (e.g. chondrites. IDPs, the Stardust sample) show large variations in isotopic composition of the major volatiles (H, C, N, and O ) even within samples, witnessing to various degrees of processing in the protosolar nebula. For ex~ ample. the very pronounced D enhancements observed in IDPs [I] . are only generated in the cold. dense component of the interstellar medium (ISM), or protoplanetary disks, through ion-molecule reactions in the presence of interstellar dust. If this isotopic anomaly has an interstellar origin, this leaves open the possibility for preservation of other isotopic signatures throughout the form ation of the Solar System. The most common form of carbon in the ISM is CO molecules, and there are two potential sources of C-13 fractionation in this reservoir: low temperature chemistry and selective photodissociation. While gas-phase chemistry in cold interstellar clouds preferentially incorporates C-13 into CO [2], the effect of self-shielding in the presence of UV radiation instead leads to a relative enhancement of the more abundant isotopologue, 12CO. Solar System organic material exhibit rather small fluctuations in delta C-13 as compared to delta N-15 and delta D [3][1], the reason for which is still unclear. However, the fact that both C-13 depleted and enhanced material exists could indicate an interstellar origin where the two fractionation processes have both played a part. Formaldehyde (H2CO) is observed in the gas-phase in a wide range of interstellar environments, as well as in cometary comae. It is proposed as an important reactant in the formation of more complex organic molecules in the heated environments around young stars, and formaldehyde polymers have been suggested as the common origin of chondritic insoluable organic matter (IOM) and cometary refractory organic solids [4]. The relatively high gas-phase abundance of H2CO observed in molecular clouds (10(exp- 9) - 10(exp- 8) relative to H2) makes it feasible to observe its less common isotopologues. As a step in our investigation of C-13 fractionation patterns in the ISM, we here present comparisons between observations of the C-13 fraction in formaldehyde, and chemical fractionation models.

Wirstrom, E. S.↗
NASA NTRS2010

Recent Developments in Three Dimensional Radiation Transport Using the Green's Function Technique

In the future, astronauts will be sent into space for longer durations of time compared to previous missions. The increased risk of exposure to dangerous radiation, such as Galactic Cosmic Rays and Solar Particle Events, is of great concern. Consequently, steps must be taken to ensure astronaut safety by providing adequate shielding. In order to better determine and verify shielding requirements, an accurate and efficient radiation transport code based on a fully three dimensional radiation transport model using the Green's function technique is being developed

Rockell, Candice↗
NASA NTRS2013

Phase Change Material for Temperature Control of Imager or Sounder on GOES Type Satellites in GEO

An imager or sounder on satellites, such as the Geostationary Operational Environmental Satellite (GOES), in geostationary orbit (GEO) has a scan mirror and motor in the scan cavity. The GEO orbit is 24 hours long. During part of the orbit, direct sunlight enters the scan aperture and adds heat to components in the scan cavity. Solar heating also increases the scan motor temperature. Overheating of the scan motor could reduce its reliability. For GOES-N to P, a radiator with a thermal louver rejects the solar heat absorbed to keep the scan cavity cool. A sunshield shields the radiator/louver from the Sun. This innovation uses phase change material (PCM) in the scan cavity to maintain the temperature stability of the scan mirror and motor. When sunlight enters the scan aperture, solar heating causes the PCM to melt. When sunlight stops entering the scan aperture, the PCM releases the thermal energy stored to keep the components in the scan cavity warm. It reduces the heater power required to make up the heat lost by radiation to space through the aperture. This is a major advantage when compared to a radiator/ louver. PCM is compact because it has a high solid-to-liquid enthalpy. Also, it could be spread out in the scan cavity. This is another advantage. Paraffin wax is a good PCM candidate, with high solid-to-liquid enthalpy, which is about 225 kJ/kg. For GOES-N to P, a radiator with a louver rejects the solar heat that enters the aperture to keep the scan cavity cool. For the remainder of the orbit, sunlight does not enter the scan aperture. However, the radiator/louver continues radiating heat to space because the louver effective emittance is about 0.12, even if the louver is fully closed. This requires makeup heater power to maintain the temperature within the stability range.

Choi, Michael↗
NASA NTRS2001

A Cryogenic Propellant Production Depot for Low Earth Orbit

The cost of access to space beyond low Earth orbit can be lowered if vehicles can refuel in orbit. The power requirements for a propellant depot that electrolyzes water and stores cryogenic oxygen and hydrogen can be met using technology developed for space solar power. A propellant depot is described that will be deployed in a 400 km circular equatorial orbit, receive tanks of water launched into a lower orbit from Earth by gun launch or reusable launch vehicle, convert the water to liquid hydrogen and oxygen, and store Lip to 500 metric tonnes of cryogenic propellants. The propellant stored in the depot can support transportation from low Earth orbit to geostationary Earth orbit, the Moon, LaGrange points, Mars, etc. The tanks are configured in an inline gravity-gradient configuration to minimize drag and settle the propellant. Temperatures can be maintained by body-mounted radiators; these will also provide some shielding against orbital debris. Power is supplied by a pair of solar arrays mounted perpendicular to the orbital plane, which rotate once per orbit to track the Sun. In the longer term, cryogenic propellant production technology can be applied to a larger LEO depot, as well as to the use of lunar water resources at a similar depot elsewhere.

Potter, Seth D.↗
NASA NTRS2006

Visual Risk Assessment of Space Radiation Exposure for Future Space Exploration Missions

Protecting astronauts from space radiation exposure during an interplanetary mission is an important challenge for mission design and operations. If sufficient protection is not provided near solar maximum, the risk can be significant due to exposure to sporadic solar particle events (SPEs) as well as to the continuous galactic cosmic radiation (GCR). Polyethylene shielded "storm shelters" inside spacecraft have been shown to limit total exposure from a large SPE to a permissible level, preventing acute risks and providing a potential approach to fulfill the ALARA (as low as reasonably achievable) requirement. For accurate predictions of radiation dose to astronauts involved in future space exploration missions, detailed variations of radiation shielding properties are required. Radiation fluences and doses vary considerably across both the spacecraft geometry and the body-shielding distribution. A model using a modern CAD tool ProE(TradeMark), which is the leading engineering design platform at NASA, has been developed to account for these local variations in the radiation distribution. Visual assessment of radiation distribution at different points inside a spacecraft module and in the human body for a given radiation environment are described. Results will ultimately guide in developing requirements for maximal protection for astronauts from space radiation.

Hussein, Hesham F.↗
NASA NTRS2002

Solar UV Radiation and the Origin of Life On Earth

We have embarked on a program aimed at understanding the atmosphere of the early Earth, because of its importance as a greenhouse, radiation shield and energy source for life. Here, we give a progress report on the first phase of this program to establish the UV radiation from the early Sun. We have obtained ultraviolet spectra (STIS, FUSE, EUVE) of carefully selected nearby, young solar-type stars, which act as surrogates for the early Sun We are making detailed non-LTE analyses of the spectra and constructing models of their photospheres + chromospheres. Once validated, these models will allow us to extrapolate our theoretical spectra to other metallicities and to unobserved spectral regions.

Heap, S. R.↗
NASA NTRS2004

Space radiation transport properties of polyethylene-based composites

Composite materials that can serve as both effective shielding materials against cosmic-ray and energetic solar particles in deep space, as well as structural materials for habitat and spacecraft, remain a critical and mission enabling component in mission planning and exploration. Polyethylene is known to have excellent shielding properties due to its low density, coupled with high hydrogen content. Polyethylene-fiber reinforced composites promise to combine this shielding effectiveness with the required mechanical properties of structural materials. Samples of polyethylene-fiber reinforced epoxy matrix composite 1-5 cm thick were prepared at the NASA Marshall Space Flight Center and tested against a 500 MeV/nucleon Fe beam at the HIMAC facility of NIRS in Chiba, Japan. This paper presents measured and calculated results for the radiation transport properties of these samples.

Polyethylene/chemistry↗
NASA NTRS2001

Solar UV Radiation and the Origin of Life on Earth

We have embarked on a program aimed at understanding the atmosphere of the early Earth, because of its importance as a greenhouse, radiation shield, and energy source for life. Here, we give a progress report on the first phase of this program: to establish the UV radiation from the early Sun. We are presently obtaining ultraviolet spectra (STIS, FUSE, EUVE) of carefully selected nearby, young solar-type stars, which act as surrogates for the early Sun. We are currently making detailed non-LTE analyses of the spectra and constructing models of their photospheres + chromospheres. once validated, these models will allow us to extrapolate our theoretical spectra to unobserved spectral regions, and to proceed to the next step: to develop photochemical models of the pre-biotic and Archean atmosphere of the Earth.

Heap, S. R.↗
NASA NTRS1999

Quantitation of Radiation Induced Deletion and Recombination Events Associated with Repeated DNA Sequences

Manned exploration of space exposes the explorers to a complex and novel radiation environment. The galactic cosmic ray and trapped belt radiation (predominantly proton) components of this environment are relatively constant, and the variations with the solar cycle are well understood and predictable. The level of radiation encountered in low earth orbits is determined by several factors, including altitude, inclination of orbit with respect to the equator, and spacecraft shielding. At higher altitudes, and on a Mars mission, the level of radiation exposure will increase significantly. A significant fraction of the dose may be delivered by solar particle events which vary dramatically in dose rate and incident particle spectrum. High-LET radiation is of particular concern. High-LET radiation, a component of galactic cosmic rays (GCR), is comprised of a variety of charged particles of various energies (10 MeV/n to 10 GeV/n), including about 87% photons, 12% helium ions, and heavy ions (including iron). These high energy particles can cause significant damage to target cells. The different particle types and energies result in different patterns of energy deposition at the molecular and cellular level in a primary target cell. They can also cause significant damage to other, nearby cells as a result of secondary particles. Protons, for instance produce secondaries that include photons, neutrons, pions, heavy particles, as well as gamma rays. Heavy ions deposit energy in a "track" in which the magnitude of the damage varies as the particle loses energy. Heavy ions produce secondary delta rays, or electrons. The distribution of damage through tissue is described by a Bragg curve which will be characteristic for different energies. Needless to say there are differences in the RBE of protons and a particles. High-LET heavy ions are particularly damaging to cells as they do continual damage throughout their track. Differences in these energy deposition patterns can significantly influence the nature of DNA damage and the ability of cellular systems to repair such damage. It has been suspected that these differences also affect the spatial distribution of damage within the DNA of the interphase cell nucleus and produce corresponding differences in endpoints related to health effects. The interaction of a single high-LET particle with chromatin has been suggested to cause multiple double strand breaks within a relatively short distance. In part this is due to the organization of DNA into chromatin fibers in which distant regions of the DNA helix can be physically juxtaposed by the various levels of coiling of the DNA. This prediction was confirmed by the detection of the generation of double strand DNA fragments of 100-2000 bp following exposure to high-LET ions (including iron).

Sinden, Richard R.↗
NASA NTRS2023

Passively Cooled Superconductors Final Report

A highly reflective spray-on coating and tile material has been under development at Kennedy Space Center (KSC) that scatters away most of the Sun’s energy, thereby allowing coated objects to remain cool in space. The best performing tile material has achieved 1% solar absorptivity while the best performing spray-on coating has achieved around 4%. Both versions passively maintain cryogenic temperatures below 120 K at 1 astronomical unit (AU) from the Sun, but the tile material consistently sustains temperatures below 90 K, which is low enough to preserve oxygen and methane in a liquid state. Besides keeping propellants cold, this “solar white” material has the potential to passively maintain high-temperature superconductors (HTS) in a superconducting state without the support of liquid nitrogen cooling. If superconductors can be operated without the added infrastructure of liquid nitrogen cooling, it may enable them to be used in space for applications like magnetic radiation shielding and efficient energy management. Long duration exposure to both galactic cosmic radiation and coronal mass ejections can pose health risks for the astronauts and increase the potential for damage to electronics. This makes shielding essential to accomplish long duration missions, particularly when astronauts are onboard. The objective of this project was to determine the extent we could keep a high-temperature superconducting (HTS) material passively chilled to maintain its superconducting state. Both the tile and spray-on versions of solar white were investigated. We focused on finding a version that could support passive cooling at 1 AU from the Sun and determined the closest operating distances for samples that were unable to perform at 1 AU. Early in the project, we selected bismuth strontium calcium copper oxide (BSCCO) as the HTS to test based on its reputable usage in superconducting wires. The version we selected was Bi-2223, which has a critical temperature of about 108 K. Sample bars with contacts for a four-point probe were obtained from Quantum Levitation: https://quantumlevitation.com/product/superconductor-bar-for-4-point-tc-experiment/.

superconductors↗
NASA NTRS1962

Analysis of Thermal-Protection Systems for Space-Vehicle Cryogenic-Propellant Tanks

Analytical techniques are presented that permit the calculation of heat-transfer rates with various thermal-protection systems for liquid-cryogenic-propellant tanks subjected to on-board, solar, and planetary heat fluxes. The thermal-protection systems considered include using closely spaced reflective surfaces (foils) and widely spaced reflective surfaces (shadow shields), insulation, arrangement of vehicle components, orientation with respect to radiant heating sources, and coatings for the control of solar absorptivity. The effectiveness of these thermal-protection systems in reducing propellant heating is shown both for ideal heat-transfer models and for a simplified hydrogen-oxygen terminal stage on a Mars mission. The proper orientation of a space-vehicle cryogenic tank with respect to the Sun is one of the more beneficial methods of reducing the heating effect of solar flux. Shadow shields can be extremely effective in reducing the propellant heating due to both solar and on-board fluxes. However, low-altitude planet orbits can result in high propellant heating rates due to planetary radiation reflected from the shields. For low-altitude orbits of more than a few days, foils appear to be desirable for all cryogenic-tank surfaces. Foils are also effective in reducing the on-board heating. A choice of shadow shields or foils cannot be made until a particular vehicle and a particular mission are chosen. The thermal conductivity of insulation materials would have to be lower by about two orders of magnitude with no increase in density before insulation could compete with reflective surfaces for use in long-duration thermal protection of cryogenic tanks in space. To demonstrate the application of the methods devised, thermal-protection systems are developed for a hydrogen-oxygen terminal stage for typical Mars missions.

SPACE VEHICLE↗