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NASA NTRS2018

Curating NASA's Past, Present, and Future Extraterrestrial Sample Collections

As codified in NASA Policy Directive 7100.10F, the Astromaterials Acquisition and Curation Office at NASA Johnson Space Center (hereafter JSC Curation) is charged with curation of all extraterrestrial material under NASA control, including future NASA missions. JSC Curation curates all or part of nine astromaterial collections in seven clean room suites: (1) Apollo Samples (1969; ISO 6-7), (2) Luna Samples (from USSR; 1972; ISO 7), (3) Antarctic Meteorites (1976; ISO 7), (4) Cosmic Dust (1981; ISO 5), (5) Microparticle Impact Collection (formerly called Space Exposed Hardware; 1985; ISO 5), (6) Genesis Solar Wind Atoms (2004; ISO 4); (7) Stardust Comet Particles (2006; ISO 5), (8) Stardust Interstellar Particles (2006; ISO 5), (9) Hayabusa Asteroid Particles (from JAXA; 2010; ISO 5). In addition to the labs that house the samples, we have installed and maintained a wide variety of facilities and infrastructure required to support the clean-rooms: more than 10 different HEPA-filtered air-handling systems, ultrapure dry gaseous nitrogen systems, an ultrapure water system (UPW) and cleaning facilities to provide clean tools and equipment for the labs. We also have sample preparation facilities for making thin sections, microtome sections, and even focused ion-beam (FIB) sections to meet the research requirements of scientists. To ensure that we are keeping the samples as pristine as possible, we routinely monitor the cleanliness of our clean rooms and infrastructure systems. This monitoring includes: daily monitoring of the quality of our UPW, weekly airborne particle counts in the labs, monthly monitoring of the stable isotope composition of the gaseous N2 system, and annual measurements of inorganic or organic contamination in processing cabinets. We track within our databases the current and ever-changing characteristics of more than 250,000 individual samples across our various collections (including the 19,141 samples on loan to 433 Principal Investigators in 24 countries). The next sample return missions that NASA will participate in are Hayabusa2 and OSIRIS-REx (Origins Spectral Interpretation Resource Identification Security - Regolith Explorer). The designs for a new state-of-the-art suite of clean rooms to house these samples at JSC have been finalized. This includes separate ISO class 5 clean rooms to house each collection, a common ISO class 7 area for general use, an ISO class 7 microtome laboratory, and a separate thin section lab. Additionally, a new cleaning facility is being designed and procedures developed that will allow for enhanced cleaning of cabinets and tools in an inorganically, organically, and biologically clean manner. We are also designing a large multi-purpose Advanced Curation laboratory that will allow us to develop the techniques necessary to fully support the Hayabusa2 and OSIRIS-REx missions, as well as future possible sample return missions (e.g., Lunar Polar Volatiles, Mars, Comet Surface). A micro-CT (micro Computed Tomography) laboratory dedicated to the study of astromaterials has come online within JSC Curation, and we plan to add additional facilities that will enable non-destructive (or minimally-destructive) analyses of astromaterials in the near future (e.g., micro-XRF (micro X-Ray Fluorescence), confocal imaging Raman Spectroscopy). These facilities will be available to: (1) develop sample handling and storage techniques for future sample return missions, (2) be utilized by PET (Positron Emission Tomography) for future sample return missions, (3) for retroactive PET-style analyses of our existing collections, and (4) for periodic assessments of the existing sample collections.

Zeigler, Ryan A.↗
NASA NTRSDate not supplied

Coarsening Up: Expanding the Particle Size Distributions of Lunar Simulants to Encompass A Comprehensive Range of Regolith Granularity

Due to a paucity of lunar regolith samples, simulated granular materials (simulants) have been developed and deployed for a variety of engineering and research purposes in an attempt to meet the requirements for lunar exploration. Broadly speaking, these manufactured materials aim to replicate the compositional (i.e., mineralogy and chemistry) and physical (e.g., particle size distribution, particle shape) profiles of lunar soil samples collected during the Apollo missions. While creating a “near-perfect” lunar simulant is prohibitive due to the unique formative processes (i.e., meteorite impacts, solar wind implantation) and conditions (anhydrous, reducing environment and exposure to radiation on the surface over billions of years) encountered on the moon, certain granular properties of the regolith can be recreated with a high level of fidelity by leveraging contemporary technologies. A fundamental physical property and descriptor, grain size can be correlated between samples and replicated through processing; however, a holistic understanding of the particle size distribution of lunar regolith must be considered when creating analog materials. This study produces particle size distributions for Apollo 16 returned samples, incorporating the sieved out >1 cm coarse-grained fraction, in order to provide a more comprehensive characterization of surficial lunar regolith grain sizes for the development of highlands-type granular analog testing materials.

R. N. Kovtun↗
NASA NTRS1985

Guide to using lunar soil and simulants for experimentation

It is pointed out that lunar soil can be described as well-graded silty sands or sandy silts with an average particle size by weight in the range from 0.040 to 0.130 mm. The density of in situ bulk lunar soil is typically 1.4 to 1.9 g/cu cm. Changes in soil from moon to laboratory are considered along with some critical differences between simulants and lunar soil. Attention is given to agglutinates, iron metal distributed throughout the agglutinatic glass, solar wind hydrogen, and major lunar minerals (anorthite, pyroxene, ilmenite, olivine). The use of lunar fines as experimental samples is discussed, and the characteristics of simulants for experiments are examined, taking into account grain size distribution, particle type distribution, a highlands simulant, and a high titanium mare simulant. Simulants for testing equipment and structures are also described.

Allton, J. H.↗
NASA NTRS1995

An empirical determination of the polytropic index for the free-streaming solar wind using Helios 1 data

Observations of solar wind proton temperatures indicate that the solar wind is heated as it moves outward toward the orbit of Earth. This heating, which may be the results of electron heat conduction and perhaps MHD waves, has proven difficult to quantify and hence is often neglected in MHD models of the solar wind. An alternate approach to finding explicit heating terms for the MHD energy equation is to use a polytropic approximation. This paper discusses the properties of the polytropic approximation and its application to the solar wind plasma. By using data from the Helios 1 spacecraft, an empirical value for the polytropic index of the free-streaming solar wind is determined. Various corrections to the data are made to account for velocity, nonuniformity in radial sampling, and stream interaction regions. The polytropic index, as derived from proton data, is found to indepedent of speed state, within statistical error, and has an average value of 1.46. If magnetic pressure is included, the polytropic index has an average value of 1.58.

Totten, T. L.↗
NASA NTRSDate not supplied

Space weathering features of anhydrous minerals in fine grains from the C-type asteroid Ryugu

Materials exposed to the space environment are expected to show optically and chemically modified properties. This process is called as space weathering and is caused mainly by micrometeoroid bombardments and solar wind implantation [1]. Thus far, the space weathering of carbonaceous asteroids has not been well understood. Regolith samples were successfully recovered from C-type asteroid Ryugu by the Hayabusa mission [2]. Ryugu samples will provide insights into the ongoing space weathering of Ryugu [3]. In this study, we investigated the space weathering of anhydrous minerals including iron sulfides, magnetite, and carbonates, which are major reservoirs of volatiles including carbon, oxygen, and sulfur in Ryugu materials. We performed scanning electron microscopy (SEM) and transmission/scanning transmission electron microscopy (TEM/STEM) analysis for Ryugu samples.

Toru Matsumoto↗
NASA NTRS2014

Space Weathering of Olivine in Lunar Soils: A Comparison to Itokawa Regolith Samples

Regolith particles from airless bodies preserve a record of the space weathering processes that occurred during their surface exposure history. These processes have major implications for interpreting remote-sensing data from airless bodies. Solar wind irradiation effects occur in the rims of exposed grains, and impact processes result in the accumulation of vapordeposited elements and other surface-adhering materials. The grains returned from the surface of Itokawa by the Hayabusa mission allow the space weathering "style" of a chondritic, asteroidal "soil" to be compared to the lunar case. Here, we present new studies of space-weathered olivine grains from lunar soils, and compare these results to olivine grains from Itokawa. Samples and Methods: We analyzed microtome thin sections of olivine grains from the 20-45 micron fractions of three lunar soils: 71061, 71501 and 10084 (immature, submature and mature, respectively). Imaging and analytical data were obtained using a JEOL 2500SE 200kV field-emission scanning-transmission electron microscope equipped with a thin-window energy-dispersive x-ray spectrometer. Similar analyses were obtained from three Hayabusa olivine grains. Results and Discussion: We observed lunar grains showing a range of solar flare track densities (from <10(exp 9) to approx.10(exp 12)/sq cm). The lunar olivines all show disordered, highly strained, nanocrystalline rims up to 150-nm thick. The disordered rim thickness is positively correlated with solar flare track density. All of the disordered rims are overlain by a Si-rich amorphous layer, ranging up to 50-nm thick, enriched in elements that are not derived from the host olivine (e.g., Ca, Al, and Ti). The outmost layer represents impact-generated vapor deposits typically observed on other lunar soil grains. The Hayabusa olivine grains show track densities <10(exp 10)/sq cm and display disordered rims 50- to 100-nm thick. The track densities are intermediate to those observed in olivines in immature and submature lunar soils and indicate surface exposures of approx. 10(exp 5) years. The outermost few nanometers of the disordered rims on Hayabusa olivines are more Si-rich and Mg- and Fe-depleted relative to the cores of the grains and likely represent a minor accumulation of impact-generated vapors or sputter deposits. Nanophase Fe metal particles are less abundant in the Hayabusa rims compared to the rims on lunar grains. Conclusions: The Hayabusa and lunar olivine grain rims have widths and microstructures consistent with formation from atomic displacement damage from solar wind ions. The space weathering features in the Hayabusa grains are similar to those observed in olivines from immature to submature lunar soils. A major difference, however, is that the Hayabusa grains appear to lack the hypervelocity impact products (melt spherules, thick vapor deposits, and abundant nanophase Fe metal particles) that are common in lunar soil grains with a similar exposure history.

Keller, L. P.↗
NASA NTRS2024

Multi-Scale Analysis of an Ilmenite Microcrater in Lunar Sample 71055

Micrometeorite impacts are a key space weathering process on the lunar surface, generating a variety of physical and chemical changes in the lunar regolith. Several experiments using nanosecond pulsed lasers to simulate micrometeorite impact have been published in the past two decades, providing a wealth of knowledge, including how minerals vary in their response to laser irradiation. Although these experiments have produced many features analogous to those observed in natural samples, none could be attributed to the passage of a shock wave, resulting instead from hot ablation. Recent femtosecond laser irradiation of olivine and enstatite have more accurately reproduced the shock textures observed in lunar samples, improving our ability to coordinate experimental and lunar sample data. Both pulsed laser experiments and studies of lunar impact craters have focused on silicates, as they comprise the bulk of the regolith. Ilmenite (FeTiO 3 ) is the most abundant opaque mineral in lunar rocks and an important sink of solar wind implanted helium. Ilmenite is known to vary in its response to radiation processing relative to the silicates, but its response to micrometeorite impact has not yet been studied in natural samples nor in the laboratory. In this investigation, we characterize an ilmenite microcrater using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to learn how ilmenite responds to impact and if there are implications for helium cycling in the regolith.

B A Cymes↗
NASA NTRS1987

Solar modulation of the cosmic radiation in the heliosphere

Changes in the solar modulation of galactic and anomalous component cosmic rays reflect changes in the structure and magnetic topology of the interplanetary medium. Therefore, to the extent that the modulation process is understood, the cosmic rays can be used as a probe of the medium to infer the extent and structure of the heliosphere in regions not directly sampled by spacecraft. The challenge to modulation theory and observation has been to determine which properties of the solar wind are most important for producing the observed modulation. Significant progress has been made in answering this question during the last solar cycle using observations from spacecraft at radii to 40 AU from the Sun and at latitudes up to 30 degrees with respect to the ecliptic. A brief summary of new results and observations (with specific attention to the STIP intervals XV-XIX) will be presented to illustrate the present state of our understanding of the relation between the solar wind and interplanetary magnetic field and the modulations of the cosmic radiation.

Mckibben, R. B.↗
NASA NTRS1994

Energetic ion distributions on both sides of the Earth's magnetopause

The Active Magnetospheric Particle Tracer Explorer/Charge Composition Explorer (AMPTE/CCE) spacecraft, with an apogee of approximately 8.8R(sub E) and an inclination of approximately 4.3 deg, sampled the outer dayside equatorial magnetosphere for extended time periods and often crossed into the magnetosheath whenever the solar wind pressure was sufficiently high to compress the magnetopause to less than 8.8R(sub E). We have analyzed ion distributions on both sides of the magnetopause in order to investigate any local time and energy dependence, giving information about physical processes at the magnetopause and the bow shock. Particle measurements are from the Charge Energy Mass (CHEM)(1.5 to 300 keV/e) and Medium-Energy Particle Analyzer (MEPA)(10 keV to 2 MeV) instruments. The wide total energy range (1.5 keV to 2 MeV) covered describes the magnetospheric distributions quite well, and for the purpose of this study, adequately describes the high-energy part of the shocked solar wind. Thus both solar wind and magnetospheric components can be recognized in a mixed particle distribution. Case studies of representative magnetopause crossings at dawn, noon, and dusk, as well as a survey of several other crossings, indicated: (1) a local time and energy dependence of magnetosheath spectra at energies greater than or equal to 50 KeV; spectra were harder at the duskside than at the dawnside and also correlated with magnetospheric activity, (2) constantly much higher intensities in the magnetosphere than in the magnetosheath at energies greater than 10 KeV and an earthward gradient in the subsolar magnetosheath. In addition to the steady state magnetosheath population there exists a burst-type component indicative of a magnetospheric source, and most of the time this is recognized as a flux transfer event. Overall, the results about the origin of the greater than or equal to 50 KeV magnetosheath ions are consistent with the continuous leakage of magnetospheric particles across a tangential discontinuity magnetopause, locally distributed according to magnetospheric drift paths. Magnetic reconnection, although present, should not be a dominant source on average, because it is not continuous in time. Fermi acceleration should not be dominant because it predicts the opposite local time asymmetry, and shock drift acceleration should be a minor contributor at E greater than or equal to 50 keV because of upper-energy cutoff limitations. Our observations also indicate a significant magnetospheric contribution to energies as low as approximately 10 KeV, where the magnetosphere-magnetosheath intensity gradient reverses. However, in orderto examine the relative strength and local time distribution of all possible sources at these energies, a detailed analysis is required.

Paschalidis, N. P↗
NASA NTRS1995

Prediction of the interplanetary magnetic field strength

A new model of the coronal and interplanetary magnetic field can predict both the interplanetary magnetic field strength and its polarity from measurements of the photospheric magnetic field. The model includes the effects of the large-scale horizontal electric currents flowing in the inner corona, of the warped heliospheric current sheet in the upper corona, and of volume currents flowing in the region where the solar wind plasma totally controls the magnetic field. The model matches the MHD solution for a simple dipole test case better than earlier source surface and current sheet models. The strength and polarity of the radial interplanetary magnetic field component predicted for quiet time samples in each year from 1977 to 1986 agree with observations made near the Earth's orbit better than the hybrid MHD-source surface model (Wang and Sheeley, 1988). The results raise the question of whether coronal holes are the only solar source of the interplantary magnetic field in the solar wind. If some interplanetary flux originates outside coronal holes, the model can match the observed field using the accepted 1.8 saturation correction factor for lambda 5250 A magnetograph observations. Requiring open flux to come exclusively from coronal holes requires and additional factor of two.

Zhao, Xuepu↗
NASA NTRS2016

Curating NASA's Past, Present, and Future Astromaterial Sample Collections

The Astromaterials Acquisition and Curation Office at NASA Johnson Space Center (hereafter JSC curation) is responsible for curating all of NASA's extraterrestrial samples. JSC presently curates 9 different astromaterials collections in seven different clean-room suites: (1) Apollo Samples (ISO (International Standards Organization) class 6 + 7); (2) Antarctic Meteorites (ISO 6 + 7); (3) Cosmic Dust Particles (ISO 5); (4) Microparticle Impact Collection (ISO 7; formerly called Space-Exposed Hardware); (5) Genesis Solar Wind Atoms (ISO 4); (6) Stardust Comet Particles (ISO 5); (7) Stardust Interstellar Particles (ISO 5); (8) Hayabusa Asteroid Particles (ISO 5); (9) OSIRIS-REx Spacecraft Coupons and Witness Plates (ISO 7). Additional cleanrooms are currently being planned to house samples from two new collections, Hayabusa 2 (2021) and OSIRIS-REx (2023). In addition to the labs that house the samples, we maintain a wide variety of infra-structure facilities required to support the clean rooms: HEPA-filtered air-handling systems, ultrapure dry gaseous nitrogen systems, an ultrapure water system, and cleaning facilities to provide clean tools and equipment for the labs. We also have sample preparation facilities for making thin sections, microtome sections, and even focused ion-beam sections. We routinely monitor the cleanliness of our clean rooms and infrastructure systems, including measurements of inorganic or organic contamination, weekly airborne particle counts, compositional and isotopic monitoring of liquid N2 deliveries, and daily UPW system monitoring. In addition to the physical maintenance of the samples, we track within our databases the current and ever changing characteristics (weight, location, etc.) of more than 250,000 individually numbered samples across our various collections, as well as more than 100,000 images, and countless "analog" records that record the sample processing records of each individual sample. JSC Curation is co-located with JSC's Astromaterials Research Office, which houses a world-class suite of analytical instrumentation and scientists. We leverage these labs and personnel to better curate the samples. Part of the cu-ration process is planning for the future, and we refer to these planning efforts as "advanced curation". Advanced Curation is tasked with developing procedures, technology, and data sets necessary for curating new types of collections as envi-sioned by NASA exploration goals. We are (and have been) planning for future cu-ration, including cold curation, extended curation of ices and volatiles, curation of samples with special chemical considerations such as perchlorate-rich samples, and curation of organically- and biologically-sensitive samples.

Zeigler, R. A.↗
NASA NTRS2019

Understanding the Space Weathering of Mercury via Simulation of Micrometeorite Impacts

Space weathering alters the surfaces of airless planetary bodies via irradiation from the solar wind and micrometeorite impacts. These processes modify the microstructure, chemical composition, and spectral properties of surface materials, typically resulting in the reddening (increasing reflectance with increasing wavelength), darkening (reducing albedo), and attenuation of characteristic absorption features in reflectance spectra. In lunar samples, these changes in optical properties are driven by the production of reduced nanophase Fe particles (npFe). Our understanding of space weathering has largely been based on data from the Moon and, more recently, near-Earth S-type asteroids. However, the environment at Mercury is significantly different, with the surface experiencing intense solar wind irradiation and higher velocity micrometeorite impacts. Additionally, the composition of Mercury’s surface varies significantly from that of the Moon, including a component with very low albedo known as low reflectance material (LRM) which is enriched with up to 4 wt.% carbon over the local mean. Our understanding of how carbon phases, including graphite, are altered as a result of these processes is limited.

McGlaun, M. L.↗
NASA NTRS2007

Genesis Concentrator Target Particle Contamination Mapping and Material Identification

The majority of surface particles were found to be < 5 microns in diameter with increasing numbers close to the optical resolution limit of 0.3 microns. Acceleration grid EDS results show that the majority of materials appear to be from the SRC shell and SLA materials which include carbon-carbon fibers and Si-rich microspheres in a possible silicone binder. Other major debris material from the SRC included white paint, kapton, collector array fragments, and Al. Image analysis also revealed that SRC materials were also found mixed with the Utah mud and salt deposits. The EDS analysis of the acceleration grid showed that particles < 1 m where generally carbon based particles. Chemical cleaning techniques with Xylene and HF in an ultrasonic bath are currently being investigated for removal of small particles by the Genesis science team as well as ultra-pure water megasonic cleaning by the JSC team [4]. Removal of organic contamination from target materials is also being investigated by the science team with the use of UV-ozone cleaning devices at JSC and Open University [5]. In preparation for solar wind oxygen analyses at UCLA and Open University [1, 2], surface particle contamination on three Genesis concentrator targets was closely examined to evaluate cleaning strategies. Two silicon carbide (Genesis sample # 60001 and 60003) and one chemical vapor deposited (CVD) 13C concentrator target (60002) were imaged and mosaic mapped with optical microscopes. The resulting full target mosaic images and particle feature maps were subsequently compared with non-flight, but flight-like, concentrator targets and sample return capsule (SRC) materials. Contamination found on the flown concentrator acceleration grid was further examined using a scanning electron microscope (SEM). Energy dispersive X-ray spectroscopy (EDS) for particle identification was subsequently compared with the optical images from the flown targets. Figure 1 show that all three targets imaged in this report are fully intact and do not show any signs of material fractures. However, previous ellipsometry results and overview imaging of both flown SiC targets show a solar wind irradiation gradient from the center focal point to the outer edge [3]. In addition, due to the hard landing, each target has experienced varying degrees of impacts, scratches, and particle debris from the spacecraft and Utah impact site.

Calaway, Michael J.↗
NASA NTRS1975

The Rosiwal Principle and the regolithic distributions of solar-wind elements

In situ accumulation of solar elements is studied for the purpose of determining the extent of applicability of the Rosiwal Principle. The Rosiwal Principle states that the grain exposure area is proportional to the fraction of the unit volume occupied by the grains, and the test involves measurement of the relative concentrations of inert gases and reactive elements across sets of lunar fines samples for which mean grain size, sorting, and minimum radius of surface correlation are known. In some cases, the quantity of an element implanted into the lunar fines from the solar wind is found to be surface correlated, and the implications of this relationship are considered. According to the Rosiwal Principle, coarse soils should retain less inert gas than fine soil. The Principle can also be applied to species volatized or sputtered from the lunar surface and redeposited locally.

Criswell, D. R.↗
NASA NTRS1973

Distribution of inert gases in fines from the Cayley-Descartes region

The inert gases in 14 different fines and in one sample of 2 to 4 mm fines from Apollo 16 were measured by mass spectroscopy with respect to trapped solar wind gases, cosmogenic gases, and 'parentless' Ar-40. Such studies are helpful for the understanding of regolith evolution, of transport of regolith fines, and of the lunar atmosphere. The Apollo 16 soils are unique because they represent, after Luna 20, the second and much more extensive record from the lunar highlands. The landing site presents the problem of materials from the Cayley Formation vs those from the Descartes Formation. There are two large, relatively fresh craters in the area, North Ray and South Ray, whose ejecta patterns may be recognized in the inert-gas record.

Walton, J. R.↗
NASA NTRS1980

Solar wind flow past Venus - Theory and comparisons

Advanced computational procedures are applied to an improved model of solar wind flow past Venus to calculate the locations of the ionopause and bow wave and the properties of the flowing ionosheath plasma in the intervening region. The theoretical method is based on a single-fluid, steady, dissipationless, magneto-hydrodynamic continuum model and is appropriate for the calculation of axisymmetric supersonic, super-Alfvenic solar wind flow past a nonmagnetic planet possessing a sufficiently dense ionosphere to stand off the flowing plasma above the subsolar point and elsewhere. Determination of time histories of plasma and magnetic field properties along an arbitrary spacecraft trajectory and provision for an arbitrary oncoming direction of the interplanetary solar wind have been incorporated in the model. An outline is provided of the underlying theory and computational procedures, and sample comparisons of the results are presented with observations from the Pioneer Venus orbiter.

Spreiter, J. R.↗
NASA NTRS1986

Comets

The nature, history, and evolution of comets are considered. Cometary ions, formed by photoionization and other processes, are forced into a highly structured ion tail by the interaction with the solar wind. The importance of comets to solar-system studies lies in the possibilities that they are well-preserved samples of either the interstellar cloud which collapsed to form the solar system or the planetesimals from which the outer planets accumulated, and that they provided either the prebiotic complex molecules from which life evolved or some volatiles necessary for the evolution of these molecules.

Neugebauer, M.↗