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At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Investigating the Feasibility of Utilizing Carbon Nanotube Fibers for Spacesuit Dust Mitigation

Historical data from the Apollo missions has compelled NASA to identify dust mitigation of spacesuits and other components as a critical path prior to sending humans on potential future lunar exploration missions. Several studies thus far have proposed passive and active countermeasures to address this challenge. However, these technologies have been primarily developed and proven for rigid surfaces such as solar cells and thermal radiators. Integration of these technologies for spacesuit dust mitigation has remained an open challenge due to the complexity of suit design. Current research investigates novel methods to enhance integration of the Electrodynamic Dust Shield (EDS) concept for spacesuits. We leverage previously proven EDS concept developed by NASA for rigid surfaces and apply new techniques to integrate the technology into spacesuits to mitigate dust contamination. The study specifically examines the feasibility of utilizing Carbon Nanotube (CNT) yarns manufactured by Rice University as electrodes in spacesuit material. Proof of concept testing was conducted at NASA Kennedy Space Center using lunar regolith simulant to understand the feasibility of the proposed techniques for spacesuit application. Results from the experiments are detailed in this paper. Potential challenges of applying this technology for spacesuits are also identified.

Electrodynamic Dust Shield↗
NASA NTRS1979

Properties of microcraters and cosmic dust of less than 1000 A dimensions

Microcraters from about 100-200 A to larger than 1000 A true diameter have been measured by SEM at magnifications of 100,000x on lunar samples 76015,24,9003 and 76015,28,9004. The cumulative size frequency distribution has a slope of approximately -2.5 for craters larger than or equal to 1000 A, approximately -1.3 between 1000 A and 400 A diameters, and approaches zero at the smallest diameters. Distributions from lunar soil grains exposed during ancient epochs have the same form. Ninety-six of ninety-seven craters observed are equidimensional, indicating equidimensional dust particles with masses as low as 10 to the -20th grams. No lower limit on cosmic dust grain sizes was established. The flux and the crater production rate derived are consistent with 12054 measurements.

Morrison, D. A.↗
NASA NTRS2011

Towards Simulating a Realistic Planetary Seismic Wavefield: The Contribution of the Megaregolith and Low-Velocity Waveguides

Lunar seismograms are distinctly different from their terrestrial counterparts. The Apollo lunar seismometers recorded moonquakes without distinct P- or S-wave arrivals; instead waves arrive as a diffuse coda that decays over several hours making the identification of body waves difficult. The unusual character of the lunar seismic wavefield is generally tied to properties of the megaregolith: it consists of highly fractured and broken crustal rock, the result of extensive bombardment of the Moon. The megaregolith extends several kilometers into the lunar crust, possibly into the mantle in some regions, and is covered by a thin coating of fine-scale dust. These materials possess very low seismic velocities that strongly scatter the seismic wavefield at high frequencies. Directly modeling the effects of the megaregolith to simulate an accurate lunar seismic wavefield is a challenging computational problem, owing to the inherent 3-D nature of the problem and the high frequencies (greater than 1 Hz) required. Here we focus on modeling the long duration code, studying the effects of the low velocities found in the megaregolith. We produce synthetic seismograms using 1-D slowness integration methodologies, GEMINI and reflectivity, and a 3-D Cartesian finite difference code, Wave Propagation Program, to study the effect of thin layers of low velocity on the surface of a planet. These codes allow us generate seismograms with dominant frequencies of approximately 1 Hz. For background lunar seismic structure we explore several models, including the recent model of Weber et al., Science, 2011. We also investigate variations in megaregolithic thickness, velocity, attenuation, and seismogram frequency content. Our results are compared to the Apollo seismic dataset, using both a cross correlation technique and integrated envelope approach to investigate coda decay. We find our new high frequency results strongly support the hypothesis that the long duration of the lunar seismic codes is generated by the presence of the low velocity megaregolith, and that the diffuse arrivals are a combination of scattered energy and multiple reverberations within this layer. The 3-D modeling indicates the extreme surface topography of the Moon adds only a small contribution to scattering effects, though local geology may play a larger role. We also study the effects of the megaregolith on core reflected and converted phases and other body waves. Our analysis indicates detection of core interacting arrivals with a polarization filter technique is robust and lends the possibility of detecting other body waves from the Moon.

Schmerr, Nicholas C.↗
NASA NTRS2012

High Angular Resolution Imaging of Solar Radio Bursts from the Lunar Surface

Locating low frequency radio observatories on the lunar surface has a number of advantages, including positional stability and a very low ionospheric radio cutoff. Here, we describe the Radio Observatory on the lunar Surface for Solar studies (ROLSS), a concept for a low frequency, radio imaging interferometric array designed to study particle acceleration in the corona and inner heliosphere. ROLSS would be deployed during an early lunar sortie or by a robotic rover as part of an unmanned landing. The preferred site is on the lunar near side to simplify the data downlink to Earth. The prime science mission is to image type II and type III solar radio bursts with the aim of determining the sites at and mechanisms by which the radiating particles are accelerated. Secondary science goals include constraining the density of the lunar ionosphere by measuring the low radio frequency cutoff of the solar radio emissions or background galactic radio emission, measuring the flux, particle mass, and arrival direction of interplanetary and interstellar dust, and constraining the low energy electron population in astrophysical sources. Furthermore, ROLSS serves a pathfinder function for larger lunar radio arrays. Key design requirements on ROLSS include the operational frequency and angular resolution. The electron densities in the solar corona and inner heliosphere are such that the relevant emission occurs below 10 M Hz, essentially unobservable from Earth's surface due to the terrestrial ionospheric cutoff. Resolving the potential sites of particle acceleration requires an instrument with an angular resolution of at least 2 deg at 10 MHz, equivalent to a linear array size of approximately one kilometer. The major components of the ROLSS array are 3 antenna arms, each of 500 m length, arranged in a Y formation, with a central electronics package (CEP) at their intersection. Each antenna arm is a linear strip of polyimide film (e.g., Kapton(TradeMark)) on which 16 single polarization dipole antennas are located by depositing a conductor (e.g., silver). The arms also contain transmission lines for carrying the radio signals from the science antennas to the CEP. Operations would consist of data acquisition during the lunar day, with data downlinks to Earth one or more times every 24 hours.

MacDowall, Robert J.↗
DOE OSTI2021

Seeking Echoes of Circumstellar Disks in Kepler Light Curves

Light echoes of flares on active stars offer the opportunity for direct detection of circumstellar dust. We revisit the problem of identifying faint echoes in postflare light curves, focusing on debris disks from ongoing planet formation. Starting with simulations, we develop an algorithm for estimating the radial extent and total mass from disk echo profiles. We apply this algorithm to light curves from over 2100 stars observed by NASA’s Kepler mission, selected for multiple short-lived flares in either the long-cadence or short-cadence data sets. While flux uncertainties in light curves from individual stars preclude useful mass limits on circumstellar disks, catalog-averaged light curves yield constraints on disk mass that are comparable to estimates from known debris disks. The average mass in micron- to millimeter-sized dust around the Kepler stars cannot exceed 10% of an Earth mass in exo-Kuiper belts or 10% of a lunar mass in the terrestrial zone. We group stars according to IR excess, based on WISE W1–W3 color, as an indicator for the presence of circumstellar dust. The mass limits are greater for stars with strong IR excess, a hint that echoes are lurking not far beneath the noise in postflare light curves. With increased sensitivity, echo detection will let time-domain astronomy complement spectroscopic and direct-imaging studies in mapping how, when, and where planets form.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2011

A Study of an Optical Lunar Surface Communications Network with High Bandwidth Direct to Earth Link

A lunar surface systems study explores the application of optical communications to support a high bandwidth data link from a lunar relay satellite and from fixed lunar assets. The results show that existing 1-m ground stations could provide more than 99% coverage of the lunar terminal at 100Mb/s data rates from a lunar relay satellite and in excess of 200Mb/s from a fixed terminal on the lunar surface. We have looked at the effects of the lunar regolith and its removal on optical samples. Our results indicate that under repeated dust removal episodes sapphire rather than fused silica would be a more durable material for optical surfaces. Disruption tolerant network protocols can minimize the data loss due to link dropouts. We report on the preliminary results of the DTN protocol implemented over the optical carrier.

lunar optical communications↗
NASA NTRS1980

Dynamics of micrometeoroids

The spatial and orbital distributions of meteoroids of mass less than 10 to the -8 g are discussed. Pioneer 8 and 9, HEOS-2 and Helios 1 observations of the smallest meteoroids leaving the solar system in hyperbolic orbits due to radiation pressure (beta particles), intermediate mass particles arriving from the heliocentric spacecraft apex direction (alpha meteoroids) and the largest micrometeoroids observed with no preferred directionality (sporadic meteoroids) are reviewed, and evidence for the three groups of dynamically different micrometeoroids in lunar microcrater statistics is indicated. The collisional model of the origin of dust particles from the dispersion of sporadic meteoroids of cometary origin due to the Poynting-Robertson effect and collisions is then applied to account for the dynamics of the beta and alpha micrometeoroids.

Gruen, G.↗
NASA NTRS1987

The nonlinear thermodynamics of meteors, noctilucent clouds, enhanced airglow and global atmospheric circulation

Two types of fundamental topological junctions of elements are deduced from a nonlinear thermodynamical model. Using this scheme, the possibility of a causal relation between fireballs and faint meteors as nonlinear sources on the one hand, and noctilucent clouds (NC) and Hoffmeister's enhanced airglow (EA) as complementary formative processes in the middle atmosphere and ionosphere, on the other hand, is examined. The principal role of the global atmospheric circulation in this relation is demonstrated. Such circulation in the mesosphere appears to prevent the neutral dust dissipated by fireballs from becoming an efficient agent in NLC generation. In this case, the behavior of ionized material deposited by both the bright and faint meteors is more probably controlled, as shown from the annual variation of the E sub s layer by the darkness of lunar eclipses and the global circulation of the lower thermosphere. The role of fireballs and neutral dust might be more significant as a source of EA phenomenon.

Rajchl, J.↗
NASA NTRS2024

Determination of Percent Area Coverage of Lunar Simulant on a Surface and Observations of Fairy Castle Structures

With NASA’s goal of returning humans to the Moon, it has become increasingly important to understand the impact of lunar regolith on spacecraft systems. The ability to measure the level of dust coverage on a surface is essential. Developing an accurate technique to determine percent area coverage is challenging due to the unique and complex layering of the dust particles on the surface, creating what is called fairy castle structures that form complex towers, bridges, and buttresses using the smallest of dust particles as building blocks. For this study, these structures have been simulated using a unique dust distributor device and imaged with a scanning electron microscope. The results show the dusted surface’s complex topology, thus demonstrating the difficulty with determining the percent area of dust coverage. Implications for dust buildup on spacecraft can include issues for heat transfer, making continuation of this research critical to support future human exploration of the Moon.

Emma J Quick↗
NASA NTRS2022

Ultraviolet Radiation

The lunar surface has a complex plasma environment due to incoming solar wind flux and charged micron-sized dust particles and the presence of solar ultraviolet (UV) radiation. UV resonance fluorescence of solar radiation provides a sensitive detection of major elemental constituents, such as H, H2, O, C, N, and noble gases in the tenuous daytime lunar atmosphere. Photoemission due to the solar UV radiation is the dominating process in the charging environment, creating a photoelectron “sheath.” Such detections were observed by LADEE UV spectrometer and the Apollo 17 UV spectrometer.

Caitlin Ahrens↗
NASA NTRS1991

Lunar and Planetary Science Conference, 21st, Houston, TX, Mar. 12-16, 1990, Proceedings

The present conference on lunar and planetary science discusses the geology and geophysics of Venus; the lunar highlands and regolith; magmatic processes of the moon and meteorites; remote sensing of the moon and Mars; chondrites, cosmic dust, and comets; ammonia-water mixtures; and the evolution of volcanism, tectonics, and volatiles on Mars. Attention is given to volcanism on Venus, pristine moon rocks, the search for Crisium Basin ejecta, Apollo 14 glasses, lunar anorthosites, the sources of mineral fragments in impact melts 15445 and 15455, and argon adsorption in the lunar atmosphere. Also discussed are high-pressure experiments on magnesian eucrite compositions, the early results of thermal diffusion in metal-sulfide liquids, preliminary results of imaging spectroscopy of the Humorum Basin region of the moon, high-resolution UV-visible spectroscopy of lunar red spots, and a radar-echo model for Mars. Other topics addressed include nitrogen isotopic signatures in the Acapulco Meteorite, tridymite and maghemite formation in an Fe-SiO smoke, and the enigma of mottled terrain on Mars.

Ryder, Graham↗
NASA NTRSDate not supplied

NASA’s Moon-to-Mars Planetary Autonomous Construction Technology Project: Overview and Status

NASA plans to land the first woman and next man on the Moon by 2025 through the initial Artemis missions. NASA and its international partners plan to establish a sustainable long-term presence on the lunar surface and build up infrastructure in the subsequent Artemis missions. The Lunar Surface Innovation Initiative (LSII), within NASA’s Space Technology Mission Directorate, aims to spur the creation of novel technologies needed for lunar surface exploration and accelerate the technology readiness of key systems and components. The primary thrust areas of LSII include sustainable power; dust mitigation; in-situ resource utilization; surface excavation, construction, and outfitting; and extreme access/extreme environments. The Moon-to-Mars Planetary Autonomous Construction Technology (MMPACT) projectwas initiated to address the lunar surface construction thrust area of LSII. The goal of the MMPACT project is to develop, deliver, and demonstrate on-demand capabilities to protect astronauts and create infrastructure on the lunar surface via construction of landing pads, habitats, shelters, roadways, berms and blast shields using lunar regolith-based materials. The MMPACT project is leveraging technology derived from NASA’s 3D Printed Mars Habitat Challenge along with contributions from other Government agencies, and multiple partners within industry and academia. The MMPACT project is comprised of three interrelated elements, construction hardware and process development; feedstock materials development; and microwave structure construction capabilities. These elements are working together to address the multiple challenges of infrastructure construction on the surface of the Moon including increased autonomy of operations, hardware operation and manufacturing under lunar environmental conditions, long-duration operation of mechanisms and parts, scale of construction activities, and material and construction requirements and standards. This presentation will summarize the status of development activities in each of the three elements, including testing of the various candidate materials, preliminary design concepts for future lunar infrastructure elements, and the vision for future technology demonstrations on the lunar surface. These demonstrations, targeting the mid-to-late 2020’s, are expected to enable landing pad construction and habitat construction resulting in commercial capabilities early in the next decade.

lunar infrastructure↗
NASA NTRS1979

Optical polarimetry of asteroids and laboratory samples

Interpretations of astronomical polarization data for more than 100 minor planets are summarized with reference to laboratory data for lunar, meteoritic, and terrestrial samples. All observed asteroids, including objects only a few kilometers in diameter, have microscopically intricate surfaces. Detailed comparisons between laboratory measurements of basaltic achondrites and telescopic results for Vesta show that its surface is particulate with a broad range of particle sizes, including a component of fine (1-5 micron) dust. The surface soils have not, however, undergone marked optical alterations as is the case for the lunar fines. For albedos greater than about 0.06, the albedo and hence the diameter can be determined with some reliability from the slope of the ascending branch of the polarization-phase curve. Many minor planets have surfaces that are remarkably uniform in albedo and texture on a hemispheric scale. A notable exception is 4 Vesta, which shows about ten percent albedo variegation between hemispheres.

Dollfus, A.↗
NASA NTRS2008

Development of the Lunar Environments Test System (LETS)

The lunar surface is an inhospitable environment to work in to say the least. The environment on the lunar surface is defined by intense ultraviolet radiation, solar wind radiation (primarily electrons and protons), electrically charged dust layers, and temperatures as low as -200 C. As NASA makes plans to send manned missions to the moon's surface, significant preparation must be undertaken to ensure that the materials and mechanical components used on those missions can survive in the harsh environment. The work presented will detail the development of the Lunar Environment Test System (LETS) at the Marshall Space Flight Center that will allow scientists and engineers the ability to test new materials, mechanical components, and proposed mission hardware in a representative lunar surface environment. The LETS encompasses all the environments of the lunar surface including vacuum, thermal extremes, vacuum ultraviolet radiation, and protons and electrons from the solar wind.

Vaughn, Jason A.↗
NASA NTRS1973

Cosmic dust in the atmosphere and in the interplanetary space at 1 AU today and in the early solar system

A description of techniques used in recent experiments to detect and analyze cosmic dust and micrometeorites is given and the results both from the study of lunar crater statistics and from in situ measurements are reviewed. The results from lunar crater statistics show an agreement with the results obtained from in situ measurements in interplanetary space and derived from zodiacal light measurements. The near earth results show an enhancement in the flux numbers. This can be caused either by secondary lunar debris or by disintegration of low density fireballs in the outer atmosphere.

Fechtig, H.↗
NASA NTRS1976

Physical properties of interplanetary grains

Morphological analyses of micrometeorite craters found on lunar rocks and laboratory simulation experiments are used to formulate a meteoritic interplanetary dust particle for optical scattering calculations that is roughly spherical and has a density of 2g cm/3. The model particle has chondritic elemental abundances and also contains a high content of finely dispersed carbon.

Brownlee, D. E.↗
NASA NTRSDate not supplied

NASA's Fission Surface Power Project

Nuclear Power for the Moon and Mars Nuclear power systems enable robust exploration of the Moon and Mars - Reliable energy production is essential to exploration missions - Fission power systems can provide abundant and continuous surface power in all environmental conditions on the Moon and Mars - Lunar night is 14.5 Earth days long - Mars has recurring planet-wide dust storms that can last for weeks - A fission system designed for a demonstration on the Moon will be directly applicable to human Mars exploration

Fission↗