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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 145 records · Page 8
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NASA NTRS1993

A picture of the moon's atmosphere

Atomic sodium is a useful tracer of the tenuous lunar atmosphere because of its high efficiency in scattering sunlight at the D1 (5896 angstroms) and D2 (5890 angstroms) wavelengths. In 1988, Earth-based instruments revealed the presence of sodium at a density of less than 50 atoms per cubic centimeter at lunar altitudes below 100 kilometers. Telescopic observations that are made with a coronograph technique to block out the disk of the moon allow a true picture of the circumlunar atmosphere to be obtained and show the presence of sodium out to a distance of several lunar radii. The distribution of sodium has a solar zenith angle dependence, suggesting that most of the sodium that reaches great altitudes is liberated from the moon's surface by solar photons (by heating or sputtering) or by solar wind impact, in contrast to a source driven by uniform micrometeor bombardment.

Flynn, Brian↗
NASA NTRS1972

Lunar orbital mass spectrometer experiment

The experiment to measure the composition and distribution of the ambient lunar atmosphere by mass spectrometer is reported. The lunar orbital mass spectrometer is described along with the calibration procedures for the instrument. Preliminary results indicate that a large number of gas molecules were observed in the vicinity of the spacecraft in lunar orbit. Many of these molecules are considered to be of spacecraft origin.

Hoffman, J. H.↗
NASA NTRS2016

Synodic and Semiannual Oscillations of Argon-40 in the Lunar Exosphere

The neutral mass spectrometer on the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft collected a trove of exospheric data, including a set of high-quality measurements of radiogenic Ar-40 over a period of 142 days. Data synthesis studies, using well-established exosphere simulation tools, show that the LADEE argon data are consistent with an exosphere-regolith interaction that is dominated by adsorption and that the desorption process generates the Armand distribution of exit velocities. The synthesis work has uncovered an apparent semiannual oscillation of argon that is consistent with temporal sequestration in the seasonal cold traps created at the poles by the obliquity of the Moon. In addition, the LADEE data provide new insight into the pristine nature of lunar regolith, its spatially varying sorption properties, and the influence of sorption processes on the synodic oscillation of the argon exosphere.

argon-40↗
NASA NTRS2002

Reference Atmosphere for Mercury

We propose that Ar-40 measured in the lunar atmosphere and that in Mercury's atmosphere is due to current diffusion into connected pore space within the crust. Higher temperatures at Mercury, along with more rapid loss from the atmosphere will lead to a smaller column abundance of argon at Mercury than at the Moon, given the same crustal abundance of potassium. Because the noble gas abundance in the Hermean atmosphere represents current effusion, it is a direct measure of the crustal potassium abundance. Ar-40 in the atmospheres of the planets is a measure of potassium abundance in the interiors, since Ar-40 is a product of radiogenic decay of K-40 by electron capture with the subsequent emission of a 1.46 eV gamma-ray. Although the Ar-40 in the Earth's atmosphere is expected to have accumulated since the late bombardment, Ar-40 in the atmospheres of Mercury and the Moon is eroded quickly by photoionization and electron impact ionization. Thus, the argon content in the exospheres of the Moon and Mercury is representative of current effusion rather than accumulation over the lifetime of the planet.

Killen, Rosemary M.↗
NASA NTRS1974

Lunar interactions: Abstracts of papers presented at the Conference on Interactions of the Interplanetary Plasma with the Modern and Ancient Moon

Reviewed are the active mechanisms relating the moon to its environment and the linkage between these mechanisms and their records in the lunar sample and geophysical data. Topics: (1) large scale plasma interactions with the moon and non-magnetic planets; (2) ancient and present day lunar surface magnetic and electric fields; (3) dynamics and evolution of the lunar atmosphere; (4) evolution of the solar plasma; (5) lunar record of solar radiations; (6) non-meteoritic and meteoritic disturbance and transport of lunar surface materials; and (7) future lunar exploration.

Criswell, D. R.↗
NASA NTRS2008

Lunar Overview

This slide presentation reviews the programs and missions that are being planned to enhance our knowledge of the moon. (1) Lunar Precursor Robotics Program (LPRP): the goal of which is to undertake robotic lunar exploration missions that will return data to advance our knowledge of the lunar environment and allow United States (US) exploration architecture objectives to be accomplished earlier and with less cost through application of robotic systems. LPRP will also reduce risk to crew and maximize crew efficiency by accomplishing tasks through precursor robotic missions, and by providing assistance to human explorers on the Moon. The missions under this program ae: the Lunar Reconnaissance Orbiter (LRO), Lunar Crater Observation and Sensing Satellite (LCROSS), Lunar Mapping Project. (2) The Altair Project, the goal of which is to land a crew of 4 to and from the surface of the moon. The vehicle, the 3 design reference missions (DRMs) and a Draft Lunar Landing schedule are briefly reviewed. (3) Lunar Science Program (LSP) which describes two different lunar missions: (1) Lunar Atmosphere & Dust Environment Explorer (LADEE), and (2) International Lunar Network (ILN).

Clinton, Raymond G., Jr.↗
NASA NTRS2014

LADEE UVS Observations of Solar Occulation by Exospheric Dust above the Lunar Limb

The Lunar Atmosphere and Dust Environment Explorer (LADEE) is a lunar orbiter launched in September 2012 that investigates the composition and temporal variation of the tenuous lunar exosphere and dust environment. The primary goals of the mission are to characterize the pristine gas and dust exosphere prior to future lunar exploration activities, which may alter the lunar environment. To address this goal, the LADEE instrument suite includes an Ultraviolet/ Visible Spectrometer (UVS), which searches for dust, Na, K, and trace gases such as OH, H2O, Si, Al, Mg, Ca, Ti, Fe, as well as other previously undetected species. UVS has two sets of optics: a limb-viewing telescope, and a solar viewing telescope. The solar viewer is equipped with a diffuser (see Figure 1a) that allows UVS to stare directly at the solar disk as the Sun starts to set (or rise from) behind the lunar limb. Solar viewer measurements generally have very high signal to noise (SNR>500) for 20-30 ms integration times. The 1-degree solar viewer field of view subtends a diameter of ~8 km at a distance of 400-450 km

pristine gas↗
NASA NTRS2014

LADEE UVS Observations of Solar Occultation by Exospheric Dust Above the Lunar Limb

The Lunar Atmosphere and Dust Environment Explorer (LADEE) is a lunar orbiter launched in September 2012 that investigates the composition and temporal variation of the tenuous lunar exosphere and dust environment. The primary goals of the mission are to characterize the pristine gas and dust exosphere prior to future lunar exploration activities, which may alter the lunar environment. To address this goal, the LADEE instrument suite includes an Ultraviolet/ Visible Spectrometer (UVS), which searches for dust, Na, K, and trace gases such as OH, H2O, Si, Al, Mg, Ca, Ti, Fe, as well as other previously undetected species. UVS has two sets of optics: a limb-viewing telescope, and a solar viewing telescope. The solar viewer is equipped with a diffuser (see Figure 1a) that allows UVS to stare directly at the solar disk as the Sun starts to set (or rise from) behind the lunar limb. Solar viewer measurements generally have very high signal to noise (SNR greater than 500) for 20-30 ms integration times. The 1-degree solar viewer field of view subtends a diameter of approximately 8 km at a distance of 400-450 km.

LADEE↗
NASA NTRSDate not supplied

A Notional Artemis Lunar Surface Exploration Package (ArLSEP) based on the Gandalf Staff Platform

Introduction: The Artemis program is planning to deliver crew and cargo to the lunar surface, but there is no current package for supporting lunar in-struments and experiments similar to the Apollo Lunar Surface Exploration Package (ALSEP). This abstract provides a possible concept for such a package using the Gandalf Staff Platform as a common core. Gandalf Staff: The Gandalf Staff is an early prototype system developed over FY’21/FY’22 using NASA Science Technology Mission Directorate (STMD) Center Information Fund (CIF) grants to de-sign, build and test “proof-of-concept” components. These components include a 24v battery powered monopole that powers a suite of subsystems, including a Graphical User Interface (GUI) for crew, surface voice and data communications, Lunar Search and Rescue (LunaSAR) navigation and communications, LiDAR, field site external lighting, 360-degree camera, and a geothermal instrument for measuring sub-surface temperature gradient. The staff can be carried independently by an Extra-Vehicular Activity (EVA) astronaut, or can be mounted into a tripod for “hands free” support at a surface site being investigated. The staff can be attached to an external solar array and power storage system for long-duration operations. [1,2] ALSEP: An ASLEP flew on each mission Apollo 12 to Apollo 17. For Apollo 11, a simplified packaged called the Early Apollo Scientific Experiments Pack-age (EASEP) was flown. Each package included a “Central Station” that provided the power and communications connected to a variety of instruments and sensors. The power was provided by a Radioisotope Thermoelectric Generator (RTG) fueled by Plutoni-um-238 generating 70 watts of power (initially, decayed over time) [3]. The communications system provide for direct to Earth data transfer from the lunar surface. Each pack-age was stowed externally in the Lunar Module (LM) Scientific Equipment (SEQ) bay with a mass up to 163 kg (Apollo 17). The crew unloaded the ALSEP from the LM and deployed the instruments on the lunar surface. Although designed to operate for only 1 year, many sites operated for up to 8 years successfully [4]. The Active Seismic Experiment (ASE) included 3 geophones for detecting seismic waves created by mortars and thumpers deployed by the crew. Other active experiments measured the lunar atmosphere, the heat flow in the subsurface, the lunar gravity and potential gravity waves, the lunar magnetic field, the solar wind and plasma interactions in cislunar space. Passive experiments included collectors for dust and cosmic rays, and retroreflectors for precise measurements of distance using a laser from Earth. The ALSEP program continues to generate insights into lunar formation and evolution. ArLSEP Concepts: The lunar surface science package for the Artemis program will hopefully exceed the capability of the ALSEP. There are multiple issues for discussion leading to the design of a new ArLSEP, needing requirements definition from the science community, NASA mission architecture, and NASA budget planners. 1. Delivery Mechanism Two possible projects currently provide capability to deliver scientific cargo to the lunar surface: 1) the Commercial Lunar Payload Services (CLPS) [5] and the Human Landing System (HLS) [6, 7]. Each project is controlled by a different organization within NASA and budgeted with different criteria although both support lunar exploration. The HLS system delivers crew (and potentially cargo) to human landing sites. If an ArLSEP is “predeployed” to such a site, the design must include power (either from the vehicle or independently) to keep the electronics functioning until deployed by the crew. If an ArLSEP is delivered on a vehicle after the crew is present on the lunar surface, safety protocols require adequate distance from the humans for impact from descent propelled sur-face regolith ejecta. This distance can not exceed the capability of the crew to walk (if no rover) to the vehicle for ArLSEP deployment. 2. Overall Guidelines The general design of ArLSEP will likely follow the ALSEP with a common system for communications and power; however, significant architecture differences between Apollo and Artemis exist. Power: The RTG will not be available for early Artemis missions nor likely follow-on Lunar Exploration Transportation Services (LETS) missions [8]. Thus, ArLSEP power must be supplied by solar arrays with sufficient battery capability to “keep alive” necessary electronics during any lunar surface eclipse period. Communication: The Artemis program is developing a series of communications satellites for lunar orbit to provide surface transmission of data and voice to Earth. Called “LunaNET”, this network is component useful for ArLSEP since south polar locations may not always have direct “line-of-sight” to Earth [9]. 3. Concept of Operations (ConOps) The general ConOps for ArLSEP is to deliver the package to lunar surface before the crew arrives, and then have the crew deploy the package after some period of time. This requires coordinated design (for power systems) and launch window (for schedule) on both the cargo and crew missions. Once the ArLSEP is deployed, it will operate autonomously for a number of years. It should be designed to be EVA compatible for crew maintenance and upgrade. 4. Notional Design (for discussion purpose only) The landing site near the South Pole is expected to have no eclipse cycle exceeding 5 days, so the “keep alive” power is 144 hours (6 days to include margin). A 12v ArLSEP will use rechargeable LiFePO4 cells, which are common in the Electric Vehicle (EV) industry. With a current of 5 amps and a 125 watt system, the mass is about 90kg. The comm. system and structure adds another 10kg, thus the “Central Station” is approximately 100kg. The solar power is collected on four arrays (each 2m above the surface), and the entire ArLSEP is designed to stow in a 2m x 1m x 1m volume. The experiment and instrument design will vary for each installation and add mass to the total (although they are expected to fit within the 2m3 volume). Seismic wave generation will likely not be provided with mortars, thus an electric “thumper” will be required. Active instruments such as imaging systems and sensing instruments will benefit from the additional power and communication capability provided by ArLSEP. Passive systems such as retroreflectors, witness plates, and cosmic dust collectors can be added to either the landing vehicle and/or the ArLSEP. With repeated HLS missions to the same human site, the ArLSEP can be expanded and easily maintained for long duration science collection on the lunar surface.

ALSEP↗
NASA NTRS1994

Infrared astronomy from the Moon

The purpose of this paper is to exhibit the advantages and limitations to infrared astronomical observations form the moon. The most obvious apparent advantage is the lack of a lunar atmosphere; radiation arriving from the universe is neither extinguished nor refracted as it approaches the lunar surface. However, the Earth's atmosphere's protection against cosmic rays is also lost, and infrared detectors are highly sensitive to irradiation by energetic particles. A second apparent advantage is the relative ease with which beams from an array of telescopes can be interferometrically combined; again the vacuum environment with constant refractive index of unity throughout, permits combination without phase delay across the entire spectral range. But thermal radiation from optical components and stray radiation from the lunar environment, just outside the light path, tend to lessen that advantage, except in narrow-spectral-band spatial interferometry, in which only the radiation in individual spectral lines is mapped, and broad-band thermal emission can be effectively filtered out. On the Moon's night side, and in polar craters on the Moon, radiative cooling should permit the attainment of high sensitivity with large telescopes. Just as the proposed Edison spacecraft primary mirror is expected to reach temperatures around 40 K, so also large lunar primary mirrors might be expected to reach temperatures in that range, making the zodiacal glow the main source of noise at wavelengths shortward of 25 micrometers. The slow rota tion of the Moon, and the lack of vibrations from natural sources such as winds, should provide advantages in guiding on specific astronomical sources. To learn as much as possible about the difficulties of remote observations in a hostile environment, Antarctic observatories should be used as test beds for the rigors of lunar observations. The strenuous requirements for successful astronomical observations from the South Pole are similar to those expected to be encountered in observations conducted from the Moon.

Harwit, Martin↗
NASA NTRS1973

Task 2 of the ultraviolet spectrometer experiment S169

The far ultraviolet spectrometer for the Apollo 17 lunar scientific mission was constructed to meet the specific requirements and technical specifications as directed by the National Aeronautics and Space Administration. The Ebert Scanning Monochromator (UVS) was derived from extensive experience in the development of a variety of Ebert scanning monochromators for experiments aboard rockets and satellites. This equipment has the capability to make quantitative measurements of the composition of the lunar atmosphere as seen from the Apollo 17 CSM in lunar orbit, and to study the spectra of a number of astronomical sources during trans-earth coast.

Goss, M. E.↗
NASA NTRS2008

Electrostatic Charging of Lunar Dust by UV Photoelectric Emissions and Solar Wind Electrons

The ubiquitous presence of dust in the lunar environment with its high adhesive characteristics has been recognized to be a major safety issue that must be addressed in view of its hazardous effects on robotic and human exploration of the Moon. The reported observations of a horizon glow and streamers at the lunar terminator during the Apollo missions are attributed to the sunlight scattered by the levitated lunar dust. The lunar surface and the dust grains are predominantly charged positively by the incident UV solar radiation on the dayside and negatively by the solar wind electrons on the night-side. The charged dust grains are levitated and transported over long distances by the established electric fields. A quantitative understanding of the lunar dust phenomena requires development of global dust distribution models, based on an accurate knowledge of lunar dust charging properties. Currently available data of lunar dust charging is based on bulk materials, although it is well recognized that measurements on individual dust grains are expected to be substantially different from the bulk measurements. In this paper we present laboratory measurements of charging properties of Apollo 11 & 17 dust grains by UV photoelectric emissions and by electron impact. These measurements indicate substantial differences of both qualitative and quantitative nature between dust charging properties of individual micron/submicron sized dust grains and of bulk materials. In addition, there are no viable theoretical models available as yet for calculation of dust charging properties of individual dust grains for both photoelectric emissions and electron impact. It is thus of paramount importance to conduct comprehensive measurements for charging properties of individual dust grains in order to develop realistic models of dust processes in the lunar atmosphere, and address the hazardous issues of dust on lunar robotic and human missions.

Abbas, Mian M.↗
NASA NTRS2008

NASA Lunar Robotics for Science and Exploration

This slide presentation reviews the robotic missions that NASA and the international partnership are undertaking to investigate the moon to support science and exploration objectives. These missions include the Lunar Reconnaissance Orbiter (LRO), Lunar Crater Observation and Sensing Satellite (LCROSS), Gravity Recovery and Interior Laboratory (GRAIL), Moon Mineralogy Mapper (MMM), Lunar Atmosphere, Dust and Environment Explorer (LADEE), and the International Lunar Network (ILN). The goals and instrumentation of these missions are reviewed.

Cohen, Barbara A.↗
NASA NTRS2014

LADEE UVS (UltraViolet Visible Spectrometer) and the Search for Lunar Exospheric Dust: A Detailed Spectral Analysis

The Lunar Atmosphere and Dust Environment Explorer (LADEE) executed science observations in lunar orbit spanning 2013-Oct-16- 2014-04-18 UT. LADEE's Ultraviolet/Visible Spectrometer (UVS) studies the composition and temporal variations of the tenuous lunar exosphere and dust environment, utilizing two sets of optics: a limb-viewing telescope, and a solar-viewer. The limb-viewing telescope observes illuminated dust and emitting gas species while the Sun is just behind the lunar limb. The solar viewer, with its diffuser, allows UVS to also stare directly at the solar disk as it approaches the limb, sampling progressively lower exosphere altitudes. Solar viewer "Occultation" activities occur at the lunar sunrise limb, as the LADEE spacecraft passes into the lunar night side, facing the Sun (the spacecraft orbit is near-equatorial retrograde). A loss of transmission of sunlight occurs by the occultation of dust grains along the line-of-sight. So-called "Inertial Limb" activities have the limb-viewing telescope pointed at the lit exosphere just after the Sun has set. Inertial Limb activities follow a similar progression of diminishing sampling altitudes but hold the solar elongation angle constant so the zodiacal light contribution remains constant while seeking to observe the weak lunar horizon glow. On the dark side of the moon, "Sodium Tail" activities pointed the limb-viewing telescope in the direction of the Moon's sodium tail (similar to anti-sunward), during different lunar phases. Of the UVS data sets, these show the largest excess of scattered blue light, indicative of the presence of small (approximately 100 nm) dust grains in the tail. Correlations are sought between dust in the sodium tail and meteor streams and magnetotail crossings to investigate impact- versus electrostatic-lofting. Once lofted, nanoparticles can become charged and picked up by the solar wind. The LADEE UVS Occultation, Inertial Limb, and Sodium Tail spectral datasets provide evidence of a lunar dust exosphere.

LADEE↗
NASA NTRS1975

Implications of atmospheric Ar-40 escape on the interior structure of the moon

Radiogenic Ar-40 escapes from the lunar atmosphere at a rate of about 2 x 10 to the 21st atoms/sec. This amounts to 8% of the rate of argon production in the entire moon by potassium decay. A curious feature of the argon escape rate is a variability with time scale of several months. It is shown that the variation in argon loss correlates with high-frequency lunar teleseismic events. The only apparent region of the moon which could possibly supply the amount of argon needed for escape via a plausible temporal mechanism is a semimolten asthenosphere which may be entirely primitive unfractionated lunar material, or an Fe-FeS core that is enriched in potassium. A core that is devoid of potassium is not compatible with the atmospheric argon measurements.

Hodges, R. R., Jr.↗