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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Development of Multifunctional Radiation Shielding Materials for Long Duration Human Exploration Beyond the Low Earth Orbit

One of the major challenges for long duration human exploration beyond the low Earth orbit and sustained human presence on planetary surfaces would be development of materials that would help minimize the radiation exposure to crew and equipment from the interplanetary radiation environment, This radiation environment consists primarily of a continuous flux of galactic cosmic rays (GCR) and transient but intense fluxes of solar energetic particles (SEP). The potential for biological damage by the relatively low percentage of high-energy heavy-ions in the GCR spectrum far outweigh that due to lighter particles because of their ionizing-power and the quality of the resulting biological damage. Although the SEP spectrum does not contain heavy ions and their energy range is much lower than that for GCRs, they however pose serious risks to astronaut health particularly in the event of a bad solar storm The primary purpose of this paper is to discuss our recent efforts in development and evaluation of materials for minimizing the hazards from the interplanetary radiation environment. Traditionally, addition of shielding materials to spacecrafts has invariably resulted in paying a penalty in terms of additional weight. It would therefore be of great benefit if materials could be developed not only with superior shielding effectiveness but also sufficient structural integrity. Such a multifunctional material could then be considered as an integral part of spacecraft structures. Any proposed radiation shielding material for use in outer space should be composed of nuclei that maximize the likelihood of projectile fragmentation while producing the minimum number of target fragments. A modeling based approach will be presented to show that composite materials using hydrogen-rich epoxy matrices reinforced with polyethylene fibers and/or fabrics could effectively meet this requirement. This paper will discuss the fabrication of such a material for a crewed vehicle. Ln addition, the capability of synthesizing radiation shielding materials for habitat structures primarily from Lunar or Martian in-situ resources will also be presented. Such an approach would significantly _reduce the cost associated with transportation of such materials and structures from earth. Results from radiation exposure measurements will be presented demonstrating the shielding effectiveness of the developed materials. Mechanical testing data will be discussed to illustrate that the specific mechanical properties of the developed composites are comparable to structural aluminum based alloys currently used for the space shuttle and space station.

Sen, S.↗
NASA NTRS1986

Radiation environment and shielding for early manned Mars missions

The problem of shielding a crew during early manned Mars missions is discussed. Requirements for shielding are presented in the context of current astronaut exposure limits, natural ionizing radiation sources, and shielding inherent in a particular Mars vehicle configuration. An estimated range for shielding weight is presented based on the worst solar flare dose, mission duration, and inherent vehicle shielding.

Hall, Stephen B.↗
NASA NTRS2016

Overview of Proposed ISRU Technology Development

ISRU involves any hardware or operation that harnesses and utilizes in-situ resources (natural and discarded) to create products and services for robotic and human exploration: Assessment of physical, mineral chemical, and volatile water resources, terrain, geology, and environment (orbital and local). Production of replacement parts, complex products, machines, and integrated systems from feedstock derived from one or more processed resources. Civil engineering, infrastructure emplacement, and structure construction using materials produced from in situ resources. Radiation shields, landing pads, roads, berms, habitats, etc. Generation and storage of electrical, thermal, and chemical energy with in situ derived materials. Solar arrays, thermal wadis, chemical batteries, etc. ISRU is a disruptive capability: Enables more affordable exploration than todays paradigm. Allows more sustainable architectures to be developed. Understand the ripple effect in the other Exploration Elements: MAV: propellant selection, higher rendezvous altitude (higher DV capable with ISRU propellants). EDL: significantly reduces required landed mass. Life Support: reduce amount of ECLSS closure, reduce trash mass carried through propulsive maneuvers. Power: ISRU drives electrical requirements, reactant and regeneration for fuel cells for landers, rovers, and habitat backup. Every Exploration Element except ISRU has some flight heritage (power, propulsion, habitats, landers, life support, etc.) ISRU will require a flight demonstration mission on Mars before it will be included in the critical path. Mission needs to be concluded at least 10 years before first human landed mission to ensure lessons learned can be incorporated into final design. ISRU Formulation team has generated a (still incomplete) list of over 75 technical questions on more than 40 components and subsystems that need to be answered before the right ISRU system will be ready for this flight demo.

Mars exploration↗
NASA NTRS1990

Space radiation shielding for a Martian habitat

Radiation shielding analyses are performed for a candidate Mars base habitat. The Langley cosmic ray transport code and the Langley nucleon transport code are used to quantify the transport and attenuation of galactic cosmic rays and solar flare protons through both the Martian atmosphere and regolith shielding. Doses at the surface and at various altitudes were calculated in a previous study using both a high-density and a low-density Mars atmosphere model. This study extends the previous low-density results to include the further transport of the ionizing radiation that reaches the surface through additional shielding provided by Martian regolith. A four-compound regolith model, which includes SiO2, Fe2O3, MgO, and CaO, was selected based on the chemistry of the Viking 1 Lander site. The spectral fluxes of heavy charged particles and the corresponding dosimetric quantities are computed for a series of thicknesses in the shield media after traversing the atmosphere. These data are then used as input to algorithms for a specific shield geometry. The results are presented as the maximum dose received in the center of the habitat versus various shield thicknesses for a base at an altitude of 0 km and 8 km.

Simonsen, Lisa C.↗
NASA NTRS1992

Concepts and strategies for lunar base radiation protection - Prefabricated versus in-situ materials

The most recently accepted environment data are used as inputs for the Langley nucleon and heavy-ion transport codes, BRYNTRN and HZETRN, to examine the shield effectiveness of lunar regolith in comparison with commercially-used shield materials in nuclear facilities. Several of the fabricated materials categorized as neutron absorbers exhibit favorable characteristics for space radiation protection. In particular, polyethylene with additive boron is analyzed with regard to response to the predicted lunar galactic cosmic ray and solar proton flare environment during the course of a complete solar cycle. Although this effort is not intended to be a definitive trade study for specific shielding recommendations, attention is given to several factors that warrant consideration in such trade studies. For example, the transporting of bulk shield material to the lunar site as opposed to regolith-moving and processing equipment is assessed on the basis of recent scenario studies. The transporting of shield material from Earth may also be a viable alternative to the use of regolith from standpoints of cost-effectiveness, EVA time required, and risk factor.

Simonsen, Lisa C.↗
NASA NTRS2019

Advances in Space Radiation Physics and Transport

The space radiation environment is a complex mixture of particle types and energies originating from sources inside and outside of the galaxy. These environments may be modified by the heliospheric and geomagnetic conditions as well as planetary bodies and vehicle or habitat mass shielding. In low Earth orbit (LEO), the geomagnetic field deflects a portion of the galactic cosmic rays (GCR) and all but the most intense solar particle events (SPE). There are also dynamic belts of trapped electrons and protons with low to medium energy and intense particle count rates. In deep space, the GCR exposure is more severe than in LEO and varies inversely with solar activity. Unpredictable solar storms also present an acute risk to astronauts if adequate shielding is not provided. Near planetary surfaces such as the Earth, moon or Mars, secondary particles are produced when the ambient deep space radiation environment interacts with these surfaces and/or atmospheres. These secondary particles further complicate the local radiation environment and modify the associated health risks. Characterizing the radiation fields in this vast array of scenarios and environments is a challenging task and is currently accomplished with a combination of computational models and dosimetry. The computational tools include models for the ambient space radiation environment, mass shielding geometry, and atomic and nuclear interaction parameters. These models are then coupled to a radiation transport code to describe the radiation field at the location of interest within a vehicle or habitat. Many new advances in these models have been made in the last decade, and the present review article focuses on the progress and contributions made by workers and collaborators at NASA in the same time frame. Although great progress has been made, and models continue to improve, significant gaps remain and are discussed in the context of planned future missions. Of particular interest is the juxtaposition of various review committee findings regarding the accuracy and gaps of combined space radiation environment, physics, and transport models with the progress achieved over the past decade. While current models are now fully capable of characterizing radiation environments in the broad range of forecasted mission scenarios, it should be remembered that uncertainties still remain and need to be addressed.

Space radiation↗
NASA NTRS2005

Exploring the Feasibility of Electrostatic Shielding for Spacecrafts

NASA is moving forward towards the agency's new vision for space exploration in the 21st Century encompassing a broad range of human and robotic missions including missions to Moon, Mars and beyond. Exposure from the hazards of severe space radiation in deep space long duration missions is the show stopper. Langley has developed state-of-the-art radiation protection and shielding technology for space missions. The payload penalty demands a very stringent requirement on the design of the spacecrafts for human deep space missions. The exploration beyond low Earth orbit (LEO) to enable routine access to more interesting regions of space will require protection from the hazards of the accumulated exposures of space radiation, Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE), and minimizing the production of secondary radiation is a great advantage. There is a need to look to new horizons for newer technologies. The present investigation explores the feasibility of using electrostatic shielding in concert with innovative materials shielding and protection technologies. The asymmetries of the radiation shielding problem would be exploited in the electrostatics shielding process. The goal is to repel enough positive charge ions so that they miss the spacecraft without attracting thermal electrons. Conclusions are drawn about the advantages the electrostatic shielding, should it be successful, would bring to the radiation protection design process.

Tripathi, R. K.↗
NASA NTRS2023

Tall Lunar Tower: An Autonomously Assembled Tower for Early Lunar Infrastructure

The Tall Lunar Tower (TLT) In-Space Assembly (ISA) team aims to design, model, fabricate, autonomously assemble, and characterize a TLT engineering development unit (EDU). The autonomous assembly of a tower also demonstrates a cross-cutting technology that can be applied to other lunar structures, such as blast shields, radiation shelters, and safe havens.

In-Space Assembly↗
NASA NTRS1992

Design of a pressurized lunar rover

A pressurized lunar rover is necessary for future long-term habitation of the moon. The rover must be able to safely perform many tasks, ranging from transportation and reconnaissance to exploration and rescue missions. Numerous designs were considered in an effort to maintain a low overall mass and good mobility characteristics. The configuration adopted consists of two cylindrical pressure hulls passively connected by a pressurized flexible passageway. The vehicle has an overall length of 11 meters and a total mass of seven metric tons. The rover is driven by eight independently powered two meter diameter wheels. The dual-cylinder concept allows a combination of articulated frame and double Ackermann steering for executing turns. In an emergency, the individual drive motors allow the option of skid steering as well. Two wheels are connected to either side of each cylinder through a pinned bar which allows constant ground contact. Together, these systems allow the rover to easily meet its mobility requirements. A dynamic isotope power system (DIPS), in conjunction with a closed Brayton cycle, supplied the rover with a continuous supply of 8.5 kW. The occupants are all protected from the DIPS system's radiation by a shield of tantalum. The large amount of heat produced by the DIPS and other rover systems is rejected by thermal radiators. The thermal radiators and solar collectors are located on the top of the rear cylinder. The solar collectors are used to recharge batteries for peak power periods. The rover's shell is made of graphite-epoxy coated with multi-layer insulation (MLI). The graphite-epoxy provides strength while the thermally resistant MLI gives protection from the lunar environment. An elastomer separates the two materials to compensate for the thermal mismatch. The communications system allows for communication with the lunar base with an option for direct communication with earth via a lunar satellite link. The various links are combined into one signal broadcast in the S-band at 2.3 GHz. The rover is fitted with a parabolic reflector disk for S-band transmission, and an omnidirectional antenna for local extravehicular activity (EVA) communication. The rover's guidance, navigation, and control subsystem consists of an inertial guidance system, an orbiting lunar satellite, and an obstacle avoidance system. In addition, the rover is equipped with a number of external fixtures including two telerobotic arms, lights, cameras, EVA storage, manlocks, a docking fixture, solar panels, thermal radiators, and a scientific airlock. In conclusion, this rover meets all of the design requirements and clearly surpasses them in the areas of mobility and maneuverability.

Bhardwaj, Manoj↗
NASA NTRS1966

Lunar Lander project: A study on future manned missions to the Moon

This project is based on designing a small lunar probe which will conduct research relating to future manned missions to the moon. The basic design calls for two experiments to be run. The first of these experiments is an enclosed environment section which will be exposed to solar radiation while on the moon. The purpose of this experiment is to determine the effect of radiation on an enclosed environment and how different shielding materials can be used to moderate this effect. The eight compartments will have the following covering materials: glass, polarized glass, plexiglass, polyurethane, and boron impregnated versions of the polyurethane and plexiglass. The enclosed atmosphere will be sampled by a mass spectrometer to determine elemental breakdown of its primary constituents. This is needed so that an accurate atmospheric processing system can be designed for a manned mission. The second experiment is a seismic study of the moon. A small penetrating probe will be shot into the lunar surface and data will be collected onboard the lander by an electronic seismograph which will store the data in the data storage unit for retrieval and transmission once every twenty-three hours. The project is designed to last ten years with possible extended life for an additional nine years at which point power requirements prevent proper functioning of the various systems.

Source record↗
NASA NTRS2008

Microwave Radiometers from 0.6 to 22 GHz for Juno, a Polar Orbiter around Jupiter

A compact instrument called the MWR (microwave radiometer) is under development at JPL for Juno, the next NASA new frontiers mission, scheduled to launch in 2011. It's purpose is to measure the thermal emission from Jupiter's atmosphere at six selected frequencies from 0.6 to 22 GHz, operating in direct detection mode, in order to quantify the distributions and abundances of water and ammonia in Jupiter's atmosphere. The goal is to understand the previously unobserved dynamics of the sub-cloud atmosphere, and to discriminate among models for planetary formation in our solar system. as part of a deep space mission aboard a solar-powered spacecraft, MWR is designed to be compact, lightweight, and low power. The receivers and control electronics are protected by a radiation-shielding enclosure on the Juno spacecraft that also provides for a benign and stable operating temperature environment. All antennas and RF transmission lines outside the vault must withstand low temperatures and the harsh radiation environment surrounding Jupiter. This paper describes the concept of the MWR instrument and presents results of one breadboard receiver channel.

Jupiter↗
NASA NTRS2008

Microwave Radiometers from 0.6 to 22 GHz for Juno, A Polar Orbiter Around Jupiter

A compact instrument called the MWR (MicroWave Radiometer) is under development at JPL for Juno, the next NASA New Frontiers mission, scheduled to launch in 2011. It's purpose is to measure the thermal emission from Jupiter's atmosphere at six selected frequencies from 0.6 to 22 GHz, operating in direct detection mode, in order to quantify the distributions and abundances of water and ammonia in Jupiter's atmosphere. The goal is to understand the previously unobserved dynamics of the sub-cloud atmosphere, and to discriminate among models for planetary formation in our solar system. As part of a deep space mission aboard a solar-powered spacecraft, MWR is designed to be compact, lightweight, and low power. The receivers and control electronics are protected by a radiation-shielding enclosure on the Juno spacecraft that would provide a benign and stable operating temperature environment. All antennas and RF transmission lines outside the vault must withstand low temperatures and the harsh radiation environment surrounding Jupiter. This paper describes the concept of the MWR instrument and presents results of one breadboard receiver channel.

Antenna↗
NASA NTRS2018

Sutter Survey: Telescope Breakthrough Enables MicroSats to Map Accessible NEOs

There are three primary reasons why it is important for NASA to develop better ways to locate and characterize Near Earth Objects (NEOs). First, NEOs are an impact hazard to the Earth and congress has mandated that NASA find 90 percent of all the Potentially Hazardous Objects (PHOs) over 140 meters by the end of 2020. NASA will fail to meet this mandate due to funding limitations and the cost and technical performance of current asteroid survey approaches. The Sutter Survey will solve this problem. Second, measuring NEO population distributions will unlock the answers to critical questions dealing with the formation and evolution of the solar system. Finally, NEOs are important targets for human exploration and they represent a virtually unlimited long term resource of valuable material for radiation shielding, propellant, and life support consumables that could make NASA'splanned deep space human exploration program affordable.

Sercel, Joel C.↗
NASA NTRSDate not supplied

Shields-1 Energetic Proton Dose Comparison from Solar Minimum and Active Periods

Shields-1 has been operating in polar low earth orbit since December 2018 as part of the CubeSat Launch Initiative (CSLI) Educational Launch of Nanosatellites (ELaNa)XIX Mission. Shields-1 has 8 Teledyne µdosimeters behind shielding. These shielded µdosimeters have high minimum proton energy thresholds. The Shields-1 electronics enclosure µdosimeter has a minimum proton threshold energy of 151 MeV. The annualized total ionizing dose (TID) in the electronics enclosure was 75.6 +/- 3.2 RAD from July-August 2019, which was a solar minimum period. In contrast, the annualized TID was 61.0 +/- 2.5 RAD in July 2023, a solar active month. The TID change can be attributed to both the reduction in radiation at the South Atlantic Anomaly (SAA) and the decrease in galactic cosmic radiation during increasing solar activity. The measured GCR dose over the poles was reduced during the July 2023 solar active period in comparison with the July 2019 solar minimum period, using the most sensitive µdosimeter channel for the measurement. Shields-1 has demonstrated the capability of measuring the changes in high energy protons in polar low earth orbit during changes in solar activity, which contributes to the understanding of Earth in the heliosphere.

Shields-1 Dosimetry Space Sciences↗
NASA NTRS1992

Galactic cosmic ray transport methods and radiation quality issues

An overview of galactic cosmic ray (GCR) interaction and transport methods, as implemented in the Langley Research Center GCR transport code, is presented. Representative results for solar minimum, exo-magnetospheric GCR dose equivalents in water are presented on a component by component basis for various thicknesses of aluminum shielding. The impact of proposed changes to the currently used quality factors on exposure estimates and shielding requirements are quantified. Using the cellular track model of Katz, estimates of relative biological effectiveness (RBE) for the mixed GCR radiation fields are also made.

Townsend, L. W.↗
NASA NTRS1985

Physiological considerations for EVA in the Space Station era

The physiological parameters that will affect EMU design and operational scheduling for the Space Station Program are discussed. The system must be designed to safely and effectively handle the increased frequency of extravehicular activity projected for longer flight periods than in the past. In order to minimize the risk of decompression sickness a proper combination of equilibration time to cabin pressure, suit pressure, and prebreathing denitrogenation, is necessary. Effective thermal exchange is projected to be automatically controlled and to have an 8-hr 1000 BTU/hr capability. Physiological changes due to adaptation to weightlessness must be considered in scheduling for their impact on performance/fatigue and in coping with motion sickness. Radiation protection to the limit of 80 rad/quarter must be achieved by scheduling to avoid periodic proton and solar flare exposure, and by additional EMU shielding. Additional EMU considerations are the control of microorganisms and the higher pressure requirement for emergency O2 purge.

Horrigan, D. J., Jr.↗
NASA NTRS1994

Cryocooler Coldfinger Heat Interceptor

Spacecraft instruments requiring cryocoolers in their design struggle to keep overall power requirements in line with feasible solar array dimensions.

cryocooler coldfinger heat interceptor radiators t↗
NASA NTRS2006

Utilizing Solar Power Technologies for On-Orbit Propellant Production

The cost of access to space beyond low Earth orbit may be reduced if vehicles can refuel in orbit. The cost of access to low Earth orbit may also be reduced by launching oxygen and hydrogen propellants in the form of water. To achieve this reduction in costs of access to low Earth orbit and beyond, a propellant depot is considered that electrolyzes water in orbit, then condenses and stores cryogenic oxygen and hydrogen. Power requirements for such a depot require Solar Power Satellite technologies. A propellant depot utilizing solar power technologies is discussed in this paper. The depot will be deployed in a 400 km circular equatorial orbit. It receives tanks of water launched into a lower orbit from Earth, converts the water to liquid hydrogen and oxygen, and stores up to 500 metric tons of cryogenic propellants. This requires a power system that is comparable to a large Solar Power Satellite capable of several 100 kW of energy. Power is supplied by a pair of solar arrays mounted perpendicular to the orbital plane, which rotates once per orbit to track the Sun. The majority of the power is used to run the electrolysis system. Thermal control is maintained by body-mounted radiators; these also provide some shielding against orbital debris. The propellant stored in the depot can support transportation from low Earth orbit to geostationary Earth orbit, the Moon, LaGrange points, Mars, etc. Emphasis is placed on the Water-Ice to Cryogen propellant production facility. A very high power system is required for cracking (electrolyzing) the water and condensing and refrigerating the resulting oxygen and hydrogen. For a propellant production rate of 500 metric tons (1,100,000 pounds) per year, an average electrical power supply of 100 s of kW is required. To make the most efficient use of space solar power, electrolysis is performed only during the portion of the orbit that the Depot is in sunlight, so roughly twice this power level is needed for operations in sunlight (slightly over half of the time). This power level mandates large solar arrays, using advanced Space Solar Power technology. A significant amount of the power has to be dissipated as heat, through large radiators. This paper briefly describes the propellant production facility and the requirements for a high power system capability. The Solar Power technologies required for such an endeavor are discussed.

Fikes, John C.↗