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NASA NTRSDate not supplied

Advances in Stereo Photogrammetry Capabilities for in-Situ Ejecta Measurements in Lunar Plume-Surface Interactions

Plume-surface interaction is a critical topic of interest as human spaceflight programs establish a renewed presence on the Moon and push onwards to Mars. The erosion of regolith and high-speed ejection of soil and rocks which occurs during a powered spacecraft landing on lunar or terrestrial bodies can pose serious risks to the vehicle during landing and to existing ground assets. Ground testing campaigns have provided data sets in relevant environments (e.g., low pressure) in tandem with predictive computational model validation. To-date, limited in-situ flight data exists to inform the study of the key phenomena of plume-surface interaction: plume-flow physics, soil erosion, and ejecta dynamics. In two upcoming lunar missions, erosion of the lunar regolith will be measured in-situ using the stereo photogrammetry technique as part of NASA’s Commercial Lunar Payload Services (CLPS) Program. The Stereo Cameras for Lunar Plume Surface Studies (SCALPSS) will use a multiple-camera system to measure the erosion of the lunar regolith due to the vehicles’ rocket engine plumes during descent and after landing. The application of stereo photogrammetry to accurately measure a realistic eroded shape has been validated in laboratory work ahead of the scheduled flights. In preparation for future CLPS, Artemis, or other lunar science missions, recent advancements have been made to measure the ejecta structure and particle dynamics in addition to the erosion of regolith using a SCALPSS-like photogrammetry system. The thickness and ejection angle of entrained soil and dust produced during plume-induced erosion can be used to determine how far debris will travel, and thus how it may impact nearby infrastructure or the landing vehicle itself. The present work highlights the development of this new flight instrumentation capability and its value to advancements in the plume-surface interaction measurement topic for lunar or planetary landings.

Olivia K. Tyrrell↗
NASA NTRS2011

Initial Observations of Lunar Impact Melts and Ejecta Flows with the Mini-RF Radar

The Mini-RF radar on the Lunar Reconnaissance Orbiter's spacecraft has revealed a great variety of crater ejecta flow and impact melt deposits, some of which were not observed in prior radar imaging. The craters Tycho and Glushko have long melt flows that exhibit variations in radar backscatter and circular polarization ratio along the flow. Comparison with optical imaging reveals that these changes are caused by features commonly seen in terrestrial lava flows, such as rafted plates, pressure ridges, and ponding. Small (less than 20 km) sized craters also show a large variety of features, including melt flows and ponds. Two craters have flow features that may be ejecta flows caused by entrained debris flowing across the surface rather than by melted rock. The circular polarization ratios (CPRs) of the impact melt flows are typically very high; even ponded areas have CPR values between 0.7-1.0. This high CPR suggests that deposits that appear smooth in optical imagery may be rough at centimeter- and decimeter- scales. In some places, ponds and flows are visible with no easily discernable source crater. These melt deposits may have come from oblique impacts that are capable of ejecting melted material farther downrange. They may also be associated with older, nearby craters that no longer have a radar-bright proximal ejecta blanket. The observed morphology of the lunar crater flows has implications for similar features observed on Venus. In particular, changes in backscatter along many of the ejecta flows are probably caused by features typical of lava flows.

Carter, Lynn M.↗
NASA NTRS1975

Tektites - Volcanic ejecta from the moon

The possibility is considered that tektites are lunar volcanic ejecta, and lunar regions are examined from which tektites could be ejected with the necessary velocities and trajectories to reach the earth. The examined regions include areas around the Lunar Transient Phenomena sites near Censorinus, Messier, Messier A, and Taruntius, the area of Mare Foecunditatis near Secchi X, areas near Cauchy and Capella, and the eastern part of Mare Tranquillitatis. Evidence of acidic volcanic activity in these regions is described in detail, including possible calderas, mudflows, and endogenous domes. It is suggested that the moon is still gently degassing and that more violent eruptions of material may still occur on rare occasions. Remotely-sensed evidence of recent lunar internal activity is noted.

Cameron, W. S.↗
NASA NTRS2009

In Situ Measurement Activities at the NASA Orbital Debris Program Office

The NASA Orbital Debris Program Office has been involved in the development of several particle impact instruments since 2003. The main objective of this development is to eventually conduct in situ measurements to better characterize the small (millimeter or smaller) orbital debris and micrometeoroid populations in the near-Earth environment. In addition, the Office also supports similar instrument development to define the micrometeoroid and lunar secondary ejecta environment for future lunar exploration activities. The instruments include impact acoustic sensors, resistive grid sensors, fiber optic displacement sensors, and impact ionization sensors. They rely on different mechanisms and detection principles to identify particle impacts. A system consisting of these different sensors will provide data that are complimentary to each other, and will provide a better description of the physical and dynamical properties (e.g., size, mass, and impact speed) of the particles in the environment. Details of several systems being considered by the Office and their intended mission objectives are summarized in this paper.

Liou, J.-C.↗
NASA NTRS2008

Comparison of Ejecta Distributions from Normal Incident Hypervelocity Impact on Lunar Regolith Simulant

The National Aeronautics and Space Administration (NASA) is progressing toward long-term lunar habitation. Critical to the design of a lunar habitat is an understanding of the lunar surface environment; of specific importance is the primary meteoroid and subsequent ejecta environment. The document, NASA SP-8013, was developed for the Apollo program and is the latest definition of the ejecta environment. There is concern that NASA SP-8013 may over-estimate the lunar ejecta environment. NASA's Meteoroid Environment Office (MEO) has initiated several tasks to improve the accuracy of our understanding of the lunar surface ejecta environment. This paper reports the results of experiments on projectile impact into powered pumice and unconsolidated JSC-1A Lunar Mare Regolith stimulant (JSC-1A) targets. The Ames Vertical Gun Range (AVGR) was used to accelerate projectiles to velocities in excess of 5 km/s and impact the targets at normal incidence. The ejected particles were detected by thin aluminum foil targets placed around the impact site and angular distributions were determined for ejecta. Comparison of ejecta angular distribution with previous works will be presented. A simplistic technique to characterize the ejected particles was formulated and improvements to this technique will be discussed for implementation in future tests.

Edwards, David L.↗
NASA NTRS1974

Ejecta from large craters on the moon - Comments on the geometric model of McGetchin et al

Amendments to a quantitative scheme developed by T. R. McGetchin et al. (1973) for predicting the distribution of ejecta from lunar basins yield substantially thicker estimates of ejecta, deposited at the basin rim-crest and at varying ranges beyond, than does the original model. Estimates of the total volume of material ejected from a basin, illustrated by Imbrium, also are much greater. Because many uncertainties affect any geometric model developed primarily from terrestrial analogs of lunar craters, predictions of ejecta thickness and volume on the moon may range within at least an order of magnitude. These problems are exemplified by the variability of T, thickness of ejecta at the rim-crest of terrestrial experimental craters. The proportion of T to crater rim-height depends critically upon scaled depth-of-burst and whether the explosive is nuclear or chemical.

Pike, R. J.↗
NASA NTRSDate not supplied

Micrometeoroid and Orbital Debris (MMOD) Testing, Ballistic Limit Equation Definition and Risk Assessment of the Exploration Extravehicular Mobility Unit (XEMU)

A well-known hazard associated with exposure to the space environment is the risk of failure due to an impact from a micrometeoroid and orbital debris (MMOD) particle. As NASA prepares to return astronauts to the moon with the Artemis program, the next generation of spacesuit is in development to support future extravehicular activities (EVAs). An MMOD impact to the spacesuit is of great concern as a large leak could prevent an astronaut from safely reaching an airlock in time resulting in a loss of life. The exploration extravehicular mobility unit (xEMU) must meet MMOD requirements for multiple environments including those in low earth orbit (LEO) as well as the meteoroid and secondary lunar regolith ejecta environments found on the lunar surface. The subject of this paper is an MMOD risk assessment of the internal xEMU configuration design developed by NASA Johnson Space Center (JSC) personnel. Assessment of the MMOD risk for an 8-hour, 2-person EVA in both LEO and on the lunar surface showed that the xEMU spacesuit meets the program technical requirement of 1 in 2500 failure odds.

Micrometeoroid↗
NASA NTRS2021

Prolonged Rock Exhumation at the Rims of Kilometer-scale Lunar Craters

Fresh impact ejecta deposits on the lunar surface can be characterized as heterogeneous mixtures of boulders, cobbles, and fine-grained regolith that are deposited on the lunar surface during the impact crater formation process. Over time, the surface boulders associated with ejecta deposits break down into fine-grained regolith due to a combination of later impacts and thermal fatigue. Nonetheless, observations of old (>2.0 Ga) kilometer-scale (0.8–2.0 km) lunar impact craters in high-resolution images reveal >1 m boulders along their rims and in their near-proximal ejecta deposits on the lunar maria. Here, we use a combination of radar and thermal-infrared data from the Lunar Reconnaissance Orbiter spacecraft to show that the rims of kilometer-sized impact craters exhibit elevated rock abundances for the lifetime of the lunar maria. We interpret these results as indicating that boulders are continually being uncovered at crater rims due to downslope movement of the overlying regolith. Moreover, rocks found at crater rims that have been exhumed from depth in geologically recent times are locally derived and unlikely to have come from other areas of the Moon. Future collection of lunar samples at crater rims will serve to mitigate the potential for sample contamination from distal sources, helping to ensure accurate geologic interpretations from the collected samples.

moon↗
NASA NTRS1978

Orbital infrared observations of lunar craters and possible implications for impact ejecta emplacement

The Apollo 17 Scanning Infrared Radiometer experiment showed that the ejecta deposits of large lunar craters (D greater than 3 km) typically exhibit uniform nighttime temperatures comparable to or less than those of the surrounding mare plains. This thermal signature implies that the surface of ejecta deposits displays block sizes typically smaller than 30 cm and that the nonblocky surface extends out to three crater radii from the crater rim. Four mechanisms are proposed to account for the observed thermal signatures.

Schultz, P. H.↗
NASA NTRS1981

Lunar craters with radar bright ejecta

The properties of the 3.8-cm radar-bright halos observed around certain lunar impact craters are compiled and compared with 70-cm radar, thermal infrared and photogeological data in order to address the nature of the halos. Diameters, positions, and radar and IR signal strengths are presented for 120 radar-bright ejecta regions of size greater than 20 km and twice the diameter of the crater. The 3.8-cm halos are noted to range in size up to 30 times that of the crater itself, although the strength of the signal from the crater and rim lies in a narrow range, while the IR halos are smaller in extent and variable in signal strength. The radar-bright ejecta are found to have a range of optical properties, and to be associated with fresh primary impact craters. Data are thus consistent with craters having radar-bright ejecta deposits having ages of less than 10 million to 1 billion years, with the radar and infrared signatures of the ejecta deposits produced by combinations of enhanced blockiness and roughness.

Thompson, T. W.↗
NASA NTRS2011

Thickness of Proximal Ejecta from the Orientale Basin from Lunar Orbiter Laser Altimeter (LOLA) Data: Implications for Multi-Ring Basin Formation

Quantifying the ejecta distribution around large lunar basins is important to understanding the origin of basin rings, the volume of the transient cavity, the depth of sampling, and the nature of the basin formation processes. We have used newly obtained altimetry data of the Moon from the Lunar Orbiter Laser Altimeter (LOLA) instrument to estimate the thickness of ejecta in the region surrounding the Orientale impact basin, the youngest and best preserved large basin on the Moon. Our measurements yield ejecta thicknesses of approx.2900 m near the Cordillera Mountains, the topographic rim of Orientale, decaying to approx.1 km in thickness at a range of 215 km. These measurements imply a volume of ejecta in the region from the Cordillera ring to a radial range of one basin diameter of approx.2.9 x 10(exp 6)cu km and permit the derivation of an ejecta-thickness decay model, which can be compared with estimates for the volume of excavation and the size of the transient cavity. These data are consistent with the Outer Rook Mountains as the approximate location of the transient cavity s rim crest and suggest a volume of approx.4.8 x 10(exp 6)cu km for the total amount of basin ejecta exterior to this location.

Fassett, Caleb I.a↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Lunar Remote Sensing: Seeing the Big Picture

The session "Lunar Remote Sensing: Seeing the Big Picture" contained the following reports:Approaches for Approximating Topography in High Resolution, Multispectral Data; Verification of Quality and Compatibility for the Newly Calibrated Clementine NIR Data Set; Near Infrared Spectral Properties of Selected Nearside and Farside Sites ; Global Comparisons of Mare Volcanism from Clementine Near-Infrared Data; Testing the Relation Between UVVIS Color and TiO2 Composition in the Lunar Maria; Color Reflectance Trends in the Mare: Implications for Mapping Iron with Multispectral Images ; The Composition of the Lunar Megaregolith: Some Initial Results from Global Mapping; Global Images of Mg-Number Derived from Clementine Data; The Origin of Lunar Crater Rays; Properties of Lunar Crater Ejecta from New 70-cm Radar Observations ; Permanent Sunlight at the Lunar North Pole; and ESA s SMART-1 Mission to the Moon: Goals, Status and First Results.

Source record↗
NASA NTRS2005

Tomographic Location of Potential Melt-Bearing Phenocrysts in Lunar Glass Spherules

In 1971, Apollo 17 astronauts collected a 10 cm soil sample (74220) comprised almost entirely of orange glass spherules. Below this, a double drive-tube core sampled a 68 cm thick horizon comprised of orange glass and black beads (crystallized equivalents of orange glass). Primitive lunar glass spherules (e.g.-A17 orange glasses) are thought to represent ejecta from lunar mare fire fountains [1, 2]. The fire-fountains were apparently driven by a combination of C-O gas ex-solution from orange glass melt and the oxidation of graphite [3, 4]. Upon eruption, magmas lost their volatiles (e.g., S, CO, CO2) to space. Evidence for volatile escape remains as volatile-rich coatings on the exteriors of many spherules [e.g., 5,6]. Moreover, [7] showed that Type I and II Fe-Ni-rich metal particles found within orange glass olivine phenocrysts, or free-floating in the glass itself, are powerful evidence for the volatile driving force for lunar fire fountains.

Ebel, D. S.↗
NASA NTRS1998

Integrated Studies of Impact-Basin Ejecta as Probes of the Lunar Crust: Imbrium and Serenitatis

The large, late, basin impacts on the Earth side of the Moon fundamentally reshaped the structure of the crust, its surface morphology, and the composition of the megaregolith and surface soils. The latest (except for Orientale on the western limb) and largest was the Imbrium impact, which produced massive ejecta deposits over much of the Procellarum region and beyond, and ejected material that mixed with surface regolith nearly Moonwide. The basins serve as natural probes into the lunar crust; therefore, understanding the nature and composition of ejecta produced by them provides information about the crust at depth. Gravity data allow modeling of the structure of the crust beneath the basins, and from such models one can infer depths of excavation and the nature of crustal response following impact.

Jolliff, Brad L.↗
NASA NTRS2008

Analysis of Regolith Simulant Ejecta Distributions from Normal Incident Hypervelocity Impact

The National Aeronautics and Space Administration (NASA) has established the Constellation Program. The Constellation Program has defined one of its many goals as long-term lunar habitation. Critical to the design of a lunar habitat is an understanding of the lunar surface environment; of specific importance is the primary meteoroid and subsequent ejecta environment. The document, NASA SP-8013 'Meteoroid Environment Model Near Earth to Lunar Surface', was developed for the Apollo program in 1969 and contains the latest definition of the lunar ejecta environment. There is concern that NASA SP-8013 may over-estimate the lunar ejecta environment. NASA's Meteoroid Environment Office (MEO) has initiated several tasks to improve the accuracy of our understanding of the lunar surface ejecta environment. This paper reports the results of experiments on projectile impact into powdered pumice and unconsolidated JSC-1A Lunar Mare Regolith simulant targets. Projectiles were accelerated to velocities between 2.45 and 5.18 km/s at normal incidence using the Ames Vertical Gun Range (AVGR). The ejected particles were detected by thin aluminum foil targets strategically placed around the impact site and angular ejecta distributions were determined. Assumptions were made to support the analysis which include; assuming ejecta spherical symmetry resulting from normal impact and all ejecta particles were of mean target particle size. This analysis produces a hemispherical flux density distribution of ejecta with sufficient velocity to penetrate the aluminum foil detectors.

Edwards, David L.↗
NASA NTRS2019

Spaceflight Hazards of Escape-Velocity-Domain Impact Ejecta in the CR3BP

As a consequence of planned/proposed human lunar activity, the long-term effects of lunar debris and ejecta resulting from large-body (> 1000 kg) impacts on the lunar surface is investigated. The Escape-Velocity-Domain (EVD) ejecta behavior is characterized in terms of destination, duration in lunar orbit, and total displaced mass. Likewise, the amount of mass sent into geosynchronous orbit is also characterized and assessed as a function of impact location in terms of Sun-Earth-Moon angle, lunar latitude and longitude, and impact angle. Finally, a threat analysis is performed on critical assets in Earth and Lunar orbit such as the I.S.S., geosynchronous satellites, prospective lunar base, and the Deep Space Gateway now under construction.

Wittal, M. M.↗
NASA NTRS1975

Exposure histories of Bench Crater rocks

A description is presented of the results of mass spectrometric analyses of the noble gases krypton and xenon, in eight Apollo 12 basaltic rocks. The significance of the results is evaluated. It is concluded that the Bench Crater rocks are not what they appear to be in their field relationships. They are not fragments ejected from bedrock by the Bench impact. Most, if not all, have had a previous history of regolith residence prior to the Bench impact. In retrospect, sampling of fresh ejecta from lunar craters during the Apollo missions turned out to be surprisingly difficult. Sampling was successful for Cone and North Ray craters where large boulders were available, but fresh South Ray ejecta was surprisingly elusive. The reported investigation shows that fresh ejecta was not obtained from Bench, and moreover, that the concept of 'radial sampling', in which the rocks sampled from a crater rim are supposed to represent the deepest material excavated, fails very badly for Bench.

Burnett, D. S.↗
NASA NTRS2008

The Use of Solar Heating and Heat Cured Polymers for Lunar Surface Stabilization

Dust ejecta can affect visibility during a lunar landing, erode nearby coated surfaces and get into mechanical assemblies of in-place infrastructure. Regolith erosion was observed at many of the Apollo landing sites. This problem needs to be addressed at the beginning of the lunar base missions, as the amount of infrastructure susceptible to problems will increase with each landing. Protecting infrastructure from dust and debris is a crucial step in its long term functionality. A proposed way to mitigate these hazards is to build a lunar launch pad. Other areas of a lunar habitat will also need surface stabilization methods to help mitigate dust hazards. Roads would prevent dust from being lifted during movement and dust free zones might be required for certain areas critical to crew safety or to critical science missions. Work at NASA Kennedy Space Center (KSC) is investigating methods of stabilizing the lunar regolith including: sintering the regolith into a solid and using heat or UV cured polymers to stabilize the surface. Sintering, a method in which powders are heated until fusing into solids, has been proposed as one way of building a Lunar launch/landing pad. A solar concentrator has been built and used in the field to sinter JSC-1 Lunar stimulant. Polymer palliatives are used by the military to build helicopter landing pads and roads in dusty and sandy areas. Those polymers are dispersed in a solvent (water), making them unsuitable for lunar use. Commercially available, solvent free, polymer powders are being investigated to determine their viability to work in the same way as the solvent borne terrestrial analog. This presentation will describe the ongoing work at KSC in this field. Results from field testing will be presented. Physical testing results, including compression and abrasion, of field and laboratory prepared samples will be presented.

Hintze, Paul↗