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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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NASA NTRSDate not supplied

The Behavior of High-Velocity Dust Generated by Lander Plumes in the Lunar Environment

Lunar lander plumes are known to accelerate fine dust to speeds exceeding 2 km/s, and the resultant ejecta may remain in lunar orbit for extended periods of time. Such ejecta could become hazardous to objects in lunar orbit as well as systems on the surface. In order to understand the impact on orbiting lunar infrastructure such as Gateway, as well as assets on the lunar surface, here we consider the dynamics of the resultant high-velocity plume ejecta. Initial conditions were set by the expected near-term lunar activity and the known cone of accelerated dust generated by previous lunar landings. The effects of regular 3-body gravitation, solar radiation pressure, and electric field are included in the model. It is found that although the majority of sub-μm dust is carried away by solar wind and electric fields, about ~10% of the dust between 1.7 km/s and 2.3 km/s reimpacts the surface, much of it near the landing site. The hazard posed by that debris is a function of lander mass and distance from the landing site. The Gateway, when orbiting in the nominal NRHO at the time of a landing, is not expected to be significantly affected by the dust. However, other spacecraft in less elliptic orbits may be at greater risk.

Ejecta↗
NASA NTRS1971

Lunar surface mechanical properties from Surveyor data.

During the Surveyor program spacecraft were successfully landed at five widely separated lunar locations. Recent computer simulations of each landing have provided more comprehensive data on the mechanical properties of the lunar surface than have been obtained previously by this method of analysis. Results show that the variations in surface bearing pressure observed at the various lunar sites are probably due to surface slope effects and do not necessarily indicate differences in soil properties at these sites. Estimates of cohesion at two sites give almost identical results and further support the conclusion that the soil properties at all sites are probably very similar. Surface pressures that resist horizontal (plowing) motion are largely due to cohesion, and density and gravitational contributions are small. It is concluded that the lunar surface bearing strength is essentially zero at the surface and, for zero surface slope, increases with penetration depth at a rate of 1.87 (plus or minus 0.33) N/cu cm. The cohesion of the lunar soil is estimated to be between 0.11 and 0.17 N/sq cm.

Jones, R. H.↗
NASA NTRS1990

Four lunar astronomical observatories - Concepts developed in the NASA 90-day study for the Human Exploration Initiative

A number of astrophysical observatory concepts were studied under the overall direction of the NASA Astrophysics Division in support of NASA's 90-day study of the Human Exploration Initiative. The four observatory concepts described here were investigated at JPL. In three of them, interferometric techniques would be used to acquire high resolution synthetic aperture images in several different parts of the electromagnetic spectrum: in the UV/visible near infrared; the submillimeter; and the very low frequency (1 to 30 MHz region). The fourth is a gravitational wave detector which uses laser optical interferometry to measure the strains induced by the passage of a gravitational wave. The observatory concepts reflect the constraints on lunar surface science deployment anticipated for the Human Exploration Initiative in the period 2002 through 2015.

Cutts, James A.↗
NASA NTRS1980

Lunar asymmetry and palaeomagnetism

A model is proposed for the early lunar evolution which accounts for the compositional asymmetry between the nearside and farside of the moon and the natural remanent magnetism of lunar rocks. According to the model, the preferred gravitational energy state consisted of an asymmetric accumulation of a liquid iron alloy (Fe-Ni and a small amount of sulfur) which displaces upwards the cold primordial undifferentiated core. The resulting depth asymmetry of the outer partially molten zone leads eventually to the subcrustal accumulation of light magnesium-rich pyroxenes and olivine, preferentially in one hemisphere, sufficient to explain the offset and also indirectly providing a possible explanation for the nearside concentration of KREEP and mass basalt. Slow downward migration of iron releases gravitational energy sufficient for convection and dynamo generation in an iron layer for about a billion years.

Stevenson, D. J.↗
NASA NTRS2004

Laser ranging to the Moon, Mars and beyond

This paper discusses the current state and the future improvements in the tests of relativistic gravity with Lunar Laser Ranging (LLR). We also consider precision gravitational tests with the future laser ranging to Mars and discuss optical design of the proposed Laser Astrometric Test of Relativity (LATOR) mission. We emphasize that already existing capabilities can offer significant improvements not only in the tests of fundamental physics, but may also establish the infrastructure for space exploration in the near future. Looking to future exploration, what characteristics are desired for the next generation of ranging devices, what is the optimal architecture that would benefit both space exploration and fundamental physics, and what fundamental questions can be investigated? We try to answer these questions.

Murphy, Thomas W. Jr.↗
NASA NTRS2021

SMD Technology Highlights

Two technology highlights from the Science Mission Directorate (SMD) Planetary Science Division and Biological and Physical Sciences division are featured: a) The Dynamic Radioisotope Power Systems Project (DRPS) may enable lunar science payloads to survive and thrive during the harsh lunar night. New robust DRPS have been built and delivered by industry and are in the process of being tested at NASA’s Glenn Research Center. b) NASA's Plant Water Management (PWM) project is demonstrating that even without the help of gravity, hydroponic plant watering methods can enable plant habitats aboard crewed or robotic space missions. On Earth, plants draw water upwards through the roots against gravity, via capillary action, which orients the plant and enables display of its canopy (foliage and branches) for optimal photosynthesis and transpiration. The plant grows above the nutrient-rich soil as the water U.S. Astronaut Kate Rubins poses with PWM after nearly doubling the science returns of the ISS experiment by drawing on her wealth of wet lab operations and handling experience—on Earth and in space.

RPS↗
NASA NTRSDate not supplied

Lunar Laser Ranging in the Artemis Era

The retroreflector arrays placed on the lunar surface by the Apollo astronauts and the Soviet Luna missions continue to contribute to our understanding of gravitational physics, Earth and Moon geophysics, geodesy, and dynamics. The key science questions addressed by Lunar Laser Ranging remain very relevant today: What is the interior structure of the Moon? Is the Equivalence Principle exact? Does the strength of gravity vary with space and time? What is the nature of spacetime? Do extra dimensions or other new physics alter the inverse square law of gravity? The lunar retroreflectors are also an essential component of the realizations of the lunar reference frames. The half-century old lunar retroreflectors continue to provide excellent ranging targets but are showing signs of degradation and the measurement error associated with their physical size and varying tilt is becoming a limitation in the quest for more precise range measurements. In addition, the clustering of the arrays in the mid-latitudes of the Moon limits their geometrical strength and coverage. The south polar region planned for Artemis presents an ideal opportunity for improving the geometric distribution. Retroreflectors utilizing a large optical cross-section single cube corner do not have tilt error associated with the existing arrays making them good options for lunar deployment. Several new retroreflectors of this type are being prepared for upcoming Commercial Lunar Payload Services missions as well as Artemis. This presentation will discuss NASA’s plans for expanding the lunar laser ranging capabilities with a focus on the Artemis Lunar Laser Retroreflector.

Stephen Merkowitz↗
NASA NTRS2009

Lunar Dust and Dusty Plasma Physics

In the plasma and radiation environment of space, small dust grains from the Moon s surface can become charged. This has the consequence that their motion is determined by electromagnetic as well as gravitational forces. The result is a plasma-like condition known as "dusty plasmas" with the consequence that lunar dust can migrate and be transported by magnetic, electric, and gravitational fields into places where heavier, neutral debris cannot. Dust on the Moon can exhibit unusual behavior, being accelerated into orbit by electrostatic surface potentials as blow-off dust, or being swept away by moving magnetic fields like the solar wind as pick-up dust. Hence, lunar dust must necessarily be treated as a dusty plasma subject to the physics of magnetohydrodynamics (MHD). A review of this subject has been given before [1], but a synopsis will be presented here to make it more readily available for lunar scientists.

Wilson, Thomas L.↗
NASA NTRSDate not supplied

Scaling of Liquefaction Systems and the Effects of Gravity

Recent exploration initiatives both by NASA and others have produced interest in the liquefaction of fluids produced through in-situ processes on the surfaces of the Moon and Mars. Liquefaction of fluids in cryogenic temperatures is routinely done at large scale for terrestrial uses, but these processes do not necessarily scale down in an economical or technologically feasible manner for the anticipated rates of initial Lunar or Martian production plants. To understand appropriate processes and scaling parameters, various options should be considered. A multi-center team at NASA considered multiple different refrigeration cycles and refrigeration integration methodologies as well as how these might fit into early liquefaction plants. These studies resulted in the conclusion that integrating the tubing on the storage tank wall (for both structural and heat spreading reasons), preferably the tank which will actually use the fluid, is the nearest path forward. Given that assumption on the general framework of the liquefaction system, there are several different heat transfer mechanisms to consider from a scaling perspective. These include forced convection heat removal to the refrigeration system (or cryocooler), conduction through the tank wall heat exchanger, and condensation (with some natural convection) on the inner tank wall. Analysis of these mechanisms shows that while there is some sensitivity to gravitational level, that within the bounds of current interest (Lunar and Martian applications), this sensitivity does not dominate the liquefaction application. While there will be some effect, perhaps in a limiting manner as the tanks approach some high fill level, system level testing on the Earth should suffice for the performance prediction and demonstration of liquefaction operations as applicable to Lunar and Martian applications. However, as one approaches orbital conditions, this general approach to liquefaction will not be appropriate as the scaling of the heat transfer mechanisms is not appropriate. At this point, other approaches will need to be developed and demonstrated in the micro-gravity environment.

Cryogenics↗
NASA NTRS1990

Astrophysics from the moon; Proceedings of the Workshop, Annapolis, MD, Feb. 5-7, 1990

The present conference on astrophysics from the moon encompasses the study of the Galaxy, external planetary systems, solar physics, stars and stellar evolution, the frontiers of Galactic, extragalactic, and cosmological astronomy, an introduction to lunar-based astronomy, concepts for lunar observatories including high-energy observatories, solar observatories, and observatories for particle astrophysics and gravitational studies. Specific issues addressed include the dynamics of Jovian atmospheres, planetary magnetospheres, flare physics, exobiology and SETI from the lunar farside, and the study of interactive stars, star formation, H II regions in absorption at low frequencies, and normal galaxies. Also addressed are the potential lunar investigation of quasars, the formation epoch, and the large-scale structure of the universe, and observational issues related to X-ray large arrays, optical interferometers, VLF radio astronomy, a UV-solar reflecting coronagraph, and a heavy-nucleus detector.

Mumma, Michael J.↗
NASA NTRS1990

Physics and astrophysics from a lunar base; Proceedings of the 1st NASA Workshop, Stanford, CA, May 19, 20, 1989

The present conference on physics and astrophysics from a lunar base encompasses space physics, cosmic ray physics, neutrino physics, experiments in gravitation and general relativity, gravitational radiation physics, cosmic background radiation, particle astrophysics, surface physics, and the physics of gamma rays and X-rays. Specific issues addressed include space-plasma physics research at a lunar base, prospects for neutral particle imaging, the atmosphere as particle detector, medium- and high-energy neutrino physics from a lunar base, muons on the moon, a search for relic supernovae antineutrinos, and the use of clocks in satellites orbiting the moon to test general relativity. Also addressed are large X-ray-detector arrays for physics experiments on the moon, and the measurement of proton decay, arcsec-source locations, halo dark matter and elemental abundances above 10 exp 15 eV at a lunar base.

Potter, A. E.↗
NASA NTRS1971

The lunar laser ranging experiment

With data from two or more well-located observing stations, the lunar range can be corrected accurately for the effects of polar motion and fluctuations in the earth's rotation rate. Very accurate corrections can be made for the earth tides at each station. It appears that the use of lasers giving roughly 0.1-msec pulse lengths is highly desirable. With them, single-shot ranging accuracies of about 3 cm are expected. The actual lunar range results will be analyzed by fitting a numerical integration for the lunar motion to the data. A mathematical model for lunar range is given. Tests of the theory of gravitation are considered.

Bender, P. L.↗
NASA NTRS1987

Lunar science from lunar laser ranging

Seventeen years of lunar ranging data have been analyzed to determine lunar second-degree moment differences, third-degree gravitational harmonics, Love number, rotational dissipation and retroreflector coordinates.

Williams, J. G.↗
NASA NTRS2012

NASA Human Spaceflight Architecture Team Cis-Lunar Analysis

The Cis-Lunar Destination Team of NASA's Human Spaceflight Architecture Teait1 (HAT) has been perfom1ing analyses of a number of cis-lunar locations to infom1 architecture development, transportation and destination elements definition, and operations. The cis-lunar domain is defined as that area of deep space under the gravitation influence of the earth-moon system, including a set of orbital locations (low earth orbit (LEO]. geosynchronous earth orbit [GEO]. highly elliptical orbits [HEO]); earth-moon libration or "Lagrange·· points (EMLl through EMLS, and in particular, EMLI and EML2), and low lunar orbit (LLO). We developed a set of cis-lunar mission concepts defined by mission duration, pre-deployment, type of mission, and location, to develop mission concepts and the associated activities, capabilities, and architecture implications. To date, we have produced two destination operations J concepts based on present human space exploration architectural considerations. We have recently begun defining mission activities that could be conducted within an EM LI or EM L2 facility.

Lupisella, M.↗