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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Catalyst comprising Ir or Ir and Ru for hydrazine decomposition

A catalyst for hydrazine decomposition consisting essentially of a carrier having a pore volume of at least 0.1 cubic centimeters per gram and a specific surface area, measured in square meters per gram, equal to 195 (C.sub.p + 0.013 + 0.736 V.sub.p) where C.sub.p is the specific heat capacity of the carrier at about 25.degree. C in calories per gram per degree and V.sub.p is the pore volume of the carrier in cubic centimeters per gram and metal of the group consisting of iridium, and mixtures consisting of iridium and ruthenium deposited on said carrier in an amount between 20% and about 40% by weight of the catalyst and distributed through the pores thereof in discrete particles sufficiently separated from each other so that they do not sinter or fuse together when the catalyst is at hydrazine decomposition temperature.

Armstrong, Warren E.↗
NASA NTRS2010

In Situ Instrumentation for Sub-Surface Planetary Geochemistry

Novel instrumentation is under development at NASA's Goddard Space Flight Center, building upon earth-based techniques for hostile environments, to infer geochemical processes important to formation and evolution of solid bodies in our Solar System. A prototype instrument, the Pulsed Neutron Generator Gamma Ray and Neutron Detectors (PNG-GRAND), has a 14 MeV pulsed neutron generator coupled with gamma ray and neutron detectors to measure quantitative elemental concentrations and bulk densities of a number of major, minor and trace elements at or below the surfaces with approximately a meter-sized spatial resolution down to depths of about 50 cm without the need to drill. PNG-GRAND's in situ a meter-scale measurements and adaptability to a variety of extreme space environments will complement orbital kilometer-scale and in-situ millimeter scale elemental and mineralogical measurements to provide a more complete picture of the geochemistry of planets, moons, asteroids and comets.

Bodnarik, J.↗
NASA NTRS2013

Leak Mitigation in Mechanically Pumped Fluid Loops for Long Duration Space Missions

Mechanically pumped fluid loops (MPFLs) are increasingly considered for spacecraft thermal control. A concern for long duration space missions is the leak of fluid leading to performance degradation or potential loop failure. An understanding of leak rate through analysis, as well as destructive and non-destructive testing, provides a verifiable means to quantify leak rates. The system can be appropriately designed to maintain safe operating pressures and temperatures throughout the mission. Two MPFLs on the Mars Science Laboratory Spacecraft, launched November 26, 2011, maintain the temperature of sensitive electronics and science instruments within a -40 deg C to 50 deg C range during launch, cruise, and Mars surface operations. With over 100 meters of complex tubing, fittings, joints, flex lines, and pumps, the system must maintain a minimum pressure through all phases of the mission to provide appropriate performance. This paper describes the process of design, qualification, test, verification, and validation of the components and assemblies employed to minimize risks associated with excessive fluid leaks from pumped fluid loop systems.

thermal controls↗
NASA NTRS2016

Asteroid Redirect Mission Proximity Operations for Reference Target Asteroid 2008 EV5

NASA's Asteroid Redirect Mission (ARM) is composed of two segments, the Asteroid Redirect Robotic Mission (ARRM), and the Asteroid Redirect Crewed Mission (ARCM). In March of 2015, NASA selected the Robotic Boulder Capture Option1 as the baseline for the ARRM. This option will capture a multi-ton boulder, (typically 2-4 meters in size) from the surface of a large (greater than approx.100 m diameter) Near-Earth Asteroid (NEA) and return it to cis-lunar space for subsequent human exploration during the ARCM. Further human and robotic missions to the asteroidal material would also be facilitated by its return to cis-lunar space. In addition, prior to departing the asteroid, the Asteroid Redirect Vehicle (ARV) will perform a demonstration of the Enhanced Gravity Tractor (EGT) planetary defense technique2. This paper will discuss the proximity operations which have been broken into three phases: Approach and Characterization, Boulder Capture, and Planetary Defense Demonstration. Each of these phases has been analyzed for the ARRM reference target, 2008 EV5, and a detailed baseline operations concept has been developed.

Reeves, David M.↗
NASA NTRS2018

Hurricane Imaging Radiometer (HIRAD) Wind Speed Retrievals and Assessment Using Dropsondes

The Hurricane Imaging Radiometer (HIRAD) is an experimental C-band passive microwave radiometer designed to map the horizontal structure of surface wind speed fields in hurricanes. New data processing and customized retrieval approaches were developed after the 2015 Tropical Cyclone Intensity (TCI) experiment, which featured flights over Hurricanes Patricia, Joaquin, Marty, and the remnants of Tropical Storm Erika. These new approaches produced maps of surface wind speed that looked more realistic than those from previous campaigns. Dropsondes from the High Definition Sounding System (HDSS) that was flown with HIRAD on a WB-57 high altitude aircraft in TCI were used to assess the quality of the HIRAD wind speed retrievals. The root mean square difference between HIRAD-retrieved surface wind speeds and dropsonde-estimated surface wind speeds was 6.0 meters per second. The largest differences between HIRAD and dropsonde winds were from data points where storm motion during dropsonde descent compromised the validity of the comparisons. Accounting for this and for uncertainty in the dropsonde measurements themselves, we estimate the root mean square error for the HIRAD retrievals as around 4.7 meters per second. Prior to the 2015 TCI experiment, HIRAD had previously flown on the WB-57 for missions across Hurricanes Gonzalo (2014), Earl (2010), and Karl (2010). Configuration of the instrument was not identical to the 2015 flights, but the methods devised after the 2015 flights may be applied to that previous data in an attempt to improve retrievals from those cases.

wind retrieval↗
NASA NTRS2018

Mission analysis for the EM-1 CubeSats EQUULEUS and OMOTENASHI

EQUULEUS is a Lunar L2 orbiter and a 6-Unit CubeSat by JAXA and the University of Tokyo. OMOTENASHI is a 6-Unit CubeSat by JAXA, the world’s smallest Lunar lander. EQUULEUS and OMOTENASHI are among the 13 secondary payloads selected by NASA to be launched with Exploration Mission-1 in 2019. Despite their limited size and cost, EQUULEUS and OMOTENASHI are challenging missions, especially in terms of trajectory design and control. EQUULEUS exploits the Earth-Sun-Moon chaotic dynamics and enter a libration point orbit around the L2 of the Earth-Moon system, using a new water propulsion system with low thrust and little propellant. This “Orbit Control Experiment” is one of the main objectives of the mission. OMOTENASHI executes a semi-hard landing that requires breaking the spacecraft to a stop just a few-hundred meters above the Moon’s surface. Both missions present new and unique challenges, where the design of the nominal trajectory is mainly driven by the constrains on orbital control capabilities, and operational and robustness considerations. This paper presents the current baselines, and give an overview of the new techniques developed for their design.

Oshima, Kenta↗
NASA NTRS2021

Volatiles Investigating Polar Exploration Rover (VIPER)

VIPER is a lunar volatiles detection and measurement mission that will be launched as a payload on the CLPS (Commercial Lunar Payload Services) provided Astrobotic's Griffin lander to the lunar south polar region. VIPER includes a suite of rover-mounted instruments that will conduct science and map volatiles (especially hydrogen-bearing volatiles). The VIPER rover is also designed to excavate volatiles such as hydrogen, oxygen, and water from the Moon. After landing the VIPER rover will travel to investigate a range of Ice Stability Regions (ISRs) across scales from 100s of meters to kilometers and conduct surface and subsurface assessment of lunar water and other volatiles. The VIPER science mission team will use the instrument data to characterize the nature of the volatiles in the area and to extrapolate these data to create global lunar water resource maps. The expected lunar surface mission duration is up to four lunar days, with active surface operations during the periods when both Sun exposure and direct to Earth (DTE) communication conditions overlap. When comm and Sun are not both available, VIPER will go into ‘Safe Haven operations’ and maintain survival temperatures until Sun and comm return. The rover is controlled in near-real time and science decisions are made both tactically (short-term) and strategically (longer-term) to achieve the mission science success criteria and objectives.

Anthony Colaprete↗
NASA NTRSDate not supplied

Overview of the Volatiles Investigating Polar Exploration Rover

The Volatiles Investigating Polar Exploration Rover (VIPER) is a lunar volatiles detection and measurement mission. VIPER will be launched to the Moon in late 2023 as a payload on the Commercial Lunar Payload Services(CLPS) flight provided by Astrobotic's Griffin lander. The VIPER rover is a solar powered, mobile robot de-signed to traverse up to 20 km during a mission lasting up to four lunar days. After landing in a south polar region, the VIPER rover will travel to investigate a range of Ice Stability Regions (ISRs) across scales from 100s of meters to kilometers and conduct surface and subsurface assessment of lunar water and other volatiles. VIPER includes a suite of rover-mounted instruments(three spectrometers and a drill), which the VIPER science mission team will use to characterize the nature of the volatiles and to create global lunar water resource maps.

planetary rover↗
NASA NTRSDate not supplied

VIPER Mission Traverse Planning – Design, Strategies, and Dynamics

The Volatiles Investigation Polar Exploration Rover (VIPER) is a lunar polar volatiles prospecting mission developed through NASA’s Science Mission Directorate (SMD) Planetary Science Di-vision[1].VIPER is scheduled to land on Mons Mouton near the lunar South Pole in late 2024. VIPER’s primary mission goal is to characterize the distribution of water and volatiles across a range of thermal environments. This characterization aims to assist in understanding the origin of lunar polar volatiles and also help evaluate the In-Situ Resource Utilization (ISRU) potential of the lunar poles. The VIPER rover is a four-wheeled robotic vehicle weighing ~450 kg. It is solar-powered and teleoperated from Earth over a line-of-sight radio link. The rover can move at up to 20 cm/s on flat terrain. Accounting for commanding, localization, navigation, and obstacle-avoidance delays, however, the effective speed is closer to 1 cm/s. This effective speed is known as “Speed Made Good” (SMG), adopted from maritime culture, and kept as a key performance metric for VIPER oper-ations planning, execution, and evaluation. The mission duration is anticipated to be more than 90 Earth days and involves up to 20 km of driving. VIPER’s prospecting payload consists of spectrometers to detect volatiles and assess concentrations, context imagers, and a drill for sub-surface measurements down to one meter depth [2]. Mobility, combined with the prospecting and drill instrument suite, makes VIPER an analytically powerful resource mapper.

Volatiles Investigation Polar Exploration Rover (V↗
NASA NTRSDate not supplied

Lunar Surface Crater Thermal Effects on Lander Radiator Performance

Lunar surface craters smaller than the spatial resolution of surface meshes used in typical Lunar surface thermal models (10 to 60 meters per pixel) may impact the accuracy of thermal model extrema predictions. The goal of this study is to investigate the thermal sensitivity of representative lander systems with realistic thermal surface orientations in bare and cratered terrain environments at relevant Artemis mission locations. This thermal analysis task investigates the impact of lunar surface craters on lander radiator performance by comparing heat rejection capability results between bare and cratered terrain environments. This study examines external body-mounted lander radiator thermal performance across varying lander heights (5.5m, 20m, 50m) and radiator orientations (horizontal, 45º tilted, and vertical) at two representative Artemis mission latitudes (-89.5ºS and -82.5ºS), spanning from the Shackleton Connecting Ridge to Mons Mouton Plateau.

Lunar Surface↗
NASA NTRS1978

Core 74001/2 - Grain size and petrology as a key to the rate of in-situ reworking and lateral transport on the lunar surface

A suite of samples from the double drive tube 74001/2 has been studied. Material from this core mainly consists of orange and black droplets interpreted to be volcanic pyroclastic ejecta. Grain size analysis indicates that this material is very homogeneous in its grain size properties. It is also the finest and best sorted suite of soil samples in the lunar collection having a mean grain size of 40 microns and a mean standard deviation of 1.75 phi. The upper 5.5 cm of this core has apparently undergone in situ reworking by meteorites over a period of about 10 million years. This reworked zone contains 'exotic' grains including basalt, mineral fragments, vitric breccias, and agglutinates. One type of agglutinate is unique and has been made primarily from orange and black glass droplets melted and welded together by micrometeorite impacts. Other agglutinates are made mainly from basaltic fragments and minerals. The amount of 'exotic' material added to the core combined with an estimate of the location of the source areas for the 'exotic' material allows us to estimate that a maximum of about 0.36 gm per sq cm of regolith surface is added from a radius of about 1 meter in 10 million years. Furthermore, no more than about 0.01 gm per sq cm of regolith surface is added from a radius of about 100 meters in 10 million years.

Mckay, D. S.↗
NASA NTRS2010

Radiation Environment and Surface Radiolytic Interactions at Mimas

Saturn's innermost principal moon Mimas shares the distinction with Europa at Jupiter of being the most irradiated icy moon in its respective planetary system, although the energetic electron energy flux at Mimas is forty times smaller than at Europa. High energy (> 10 MeV) proton fluxes are low in this moon's orbital corridor, likely since slowly diffusing protons from the weak but steady source of cosmic ray albedo neutron decay (CRAND) cannot accumulate without impacting the moon surface. Lower energy proton fluxes are also evidently suppressed in this orbital region. Plasma ion and electron fluxes are also low apparently due to cooling by interaction with E-ring dust and neutral gas from Enceladus. Due to energy-dependent effects of longitudinal gradient-curvature drift for the electrons, the trailing hemisphere is mainly irradiated by electrons at energies below 1 MeV that drift relative to Mimas in the prograde direction of orbital motion around Saturn, while higher energy electrons primarily impact the leading hemisphere. Plasma ions in the inner magnetosphere of Saturn are mainly pickup ions forming from the dissociation products of Enceladus plume water molecules, additionally including some contribution from photosputtering of the main rings, and do not introduce new elemental materials at Mimas via surface implantation from the corotating plasma. Thus the primary interaction at the surface is radiolytic chemistry induced in pure water ice by relatively deep penetration of the energetic electrons to millimeter and greater depths, as compared to the micron depths impacted by the corotating plasma ions. If surface erosion by sputtering from relatively low fluxes of the plasma and more energetic ions is indeed ineffective, then molecular products (OH, H2O2, 02, 03) of the radiolytic interactions may accumulate in the meters-deep impact regolith of the surface ices. An effect of regolith trapped gas accumulation could be to increase porosity and reduce thermal conductivity of the ice, potentially contributing to reported thermal anomalies from Cassini infrared map observations. Low amplitude of trailing-leading asymmetry in optical albedo and color maps at Mimas is suggestive of relative weakness of asymmetrical effects from low-energy ions. Greater induced asymmetries are expected and observed for the moons beyond Enceladus in the middle magnetospheric region of hot plasma ions at much greater fluxes than at Mimas. Low density (1.15 g/cc) of this moon indicates paucity of mineral salts and radiogenic heating to maintain subsurface liquids, so Enceladus-like cryovolcanism as a resurfacing process is unlikely despite closer proximity to Saturn, greater tidal forcing, and more intense surface irradiation than for Enceladus.

Cooper, J. F.↗
NASA NTRS2015

Lunar Crater Ejecta: Physical Properties Revealed by Radar and Thermal Infrared Observations

We investigate the physical properties, and changes through time, of lunar impact ejecta using radar and thermal infrared data. We use data from two instruments on the Lunar Reconnaissance Orbiter (LRO) - the Diviner thermal radiometer and the Miniature Radio Frequency (Mini-RF) radar instrument - together with Earth-based radar observations. We use this multiwavelength intercomparison to constrain block sizes and to distinguish surface from buried rocks in proximal ejecta deposits. We find that radar-detectable rocks buried within the upper meter of regolith can remain undisturbed by surface processes such as micrometeorite bombardment for greater than 3 Gyr. We also investigate the thermophysical properties of radar-dark haloes, comprised of fine-grained, rock-poor ejecta distal to the blocky proximal ejecta. Using Diviner data, we confirm that the halo material is depleted in surface rocks, but show that it is otherwise thermophysically indistinct from background regolith. We also find that radar-dark haloes, like the blocky ejecta, remain visible in radar observations for craters with ages greater than 3 Ga, indicating that regolith overturn processes cannot replenish their block populations on that timescale.

Ghent, R. R.↗
NASA NTRS1972

Radar mapping of lunar surface roughness.

Comparison of anomalous behavior at infrared and radar wavelengths provides an estimation of lunar surface structure at centimeter-to-meter sizes. Although a simple classification is used, it is shown that the combination of the infrared and radar data contains more information than any of the sets by themselves. The infrared data indicate that bare surface rocks are the source of the roughness which generates enhanced radar backscatter. The different radar maps indicate the size of surface rocks, as was demonstrated for the strewn fields of centimeter-sized rubble (the Type II anomaly). As craters age, they have a rim-bright appearance in the radar maps, and eventually lose their anomalous-behavior at infrared and 3.8-cm radar wavelengths.

Thompson, T. W.↗
NASA NTRS1992

Surface navigation on Mars with a Navigation Satellite

Radiometric navigation data from the Deep Space Network (DSN) stations on the earth to transponders and other surface elements such as rovers and landers on Mars, can determine their positions to only within a kilometer in inertial space. The positional error is mostly in the z-component of the surface element parallel to the Martian spin-axis. However, with Doppler and differenced-Doppler data from a Navigation Satellite in orbit around Mars to two or more of such transponders on the planetary surface, their positions can be determined to within 15 meters (or 20 meters for one-way Doppler beacons on Mars) in inertial space. In this case, the transponders (or other vehicles) on Mars need not even be capable of directly communicating to the earth. When the Navigation Satellite data is complemented by radiometric observations from the DSN stations also, directly to the surface elements on Mars, their positions can be determined to within 3 meters in inertial space. The relative positions of such surface elements on Mars (relative to one another) in Mars-fixed coordinates, however, can be determined to within 5 meters from simply range and Doppler data from the DSN stations to the surface elements. These results are obtained from covariance studies assuming X-band data noise levels and data-arcs not exceeding 10 days. They are significant in the planning and deployment of a Mars-based navigation network necessary to support real-time operations during critical phases of manned exploration of Mars.

Vijayaraghavan, A.↗
NASA NTRS1991

The 4-meter lunar engineering telescope

The 16-meter diffraction limited lunar telescope incorporates a primary mirror with 312 one-meter segments; 3 nanometer active optics surface control with laser metrology and hexapod positioners; a space frame structure with one-millimeter stability; and a hexapod mount for pointing. The design data needed to limit risk in this development can be obtained by building a smaller engineering telescope on the moon with all of the features of the 16-meter design. This paper presents a 4.33-meter engineering telescope concept developed by the Summer 1990 Student Program of the NASA/JHU Space Grant Consortium Lunar Telescope Project. The primary mirror, made up of 18 one-meter hexagonal segments, is sized to provide interesting science as well as engineering data. The optics are configured as a Ritchey-Chretien with a coude relay to the focal plane beneath the surface. The optical path is continuously monitored with 3-nanometer precision interferometrically. An active optics processor and piezoelectric actuators operate to maintain the end-to-end optical configuration established by wave front sensing using a guide star. The mirror segments, consisting of a one-centimeter thick faceplate on 30-cm deep ribs, maintain the surface figure to a few nanometers under lunar gravity and thermal environment.

Peacock, Keith↗
NASA NTRS1973

Remote measurement of salinity: Repeated measurements over a single flight line near the Mississippi Sound

Experiments to remotely determine sea water salinity from measurements of the sea surface radiometric temperature over the Mississippi Sound were conducted. The line was flown six times at an altitude of 244 meters. The radiometric temperature of the sea surface was measured in two spectral intervals. The specifications of the equipment and the conditions under which the tests were conducted are described. Results of the tests are presented in the form of graphs.

Thomann, G. C.↗
NASA NTRS1984

In Situ Measurement of Ground-Surface Flow Resistivity

New instrument allows in situ measurement of flow resistivity on Earth's ground surface. Nonintrusive instrument includes specimen holder inserted into ground. Flow resistivity measured by monitoring compressed air passing through flow-meters; pressure gages record pressure at ground surface. Specimen holder with knife-edged inner and outer cylinders easily driven into ground. Air-stream used in measuring flow resistivity of ground enters through quick-connect fitting and exits through screen and venthole.

Zuckerwar, A. J.↗