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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 NTRS1997

There's Iron in Them Thar Hills: A Geologic Look at the Aristarchus Plateau as a Potential Landing Site for Human Lunar Return

Lunar pyroclastic deposits are unique among lunar soils. Composed of very fine grained glass beads rich in Fe, Ti and Mg they yield unique spectral signatures. From the spectra two major classes and five subclasses of lunar dark mantling deposits have been identified. Recent work by me and others has shown that the larger regional deposits are more numerous, extensive, thicker, and widely distributed than previously thought, leading us to suggest that they would make ideal resource feedstock for future lunar surface activities. Returned sample studies and the recently collected Galileo and Clementine data also corroborate these findings. Recent planning for return to the Moon indicates that large cost savings can result from using locally produced oxygen, and recent JSC laboratory results indicate that iron-rich pyroclastic dark mantling deposits may be the richest oxygen resource on the Moon. My earlier work demonstrated that instead of using regolith, bulk lunar pyroclastic deposits are better suited for beneficiation as they are thick (lO's m's), unconsolidated, fine-grained deposits. In addition, the lack of rocks and boulders and the typically flat to gently rolling terrain will facilitate their mining and processing. In preparation for the Human Lunar Return (HLR) I have characterized the Aristarchus Plateau (24 deg. N 52 deg. W) as a potential landing site for an in-situ resource utilization (ISRU) demonstration. The geologic diversity and large volume of Fe-rich pyroclastic material present at the Aristarchus site make it an ideal target for extracting O2, H2 and halogens. This paper (1) describes the current understanding of the geology of Aristarchus plateau; (2) describes the resource potential of the Aristarchus plateau; and (3) presents several candidate landing sites on the plateau for future lunar activities.

Coombs, Cassandra R.↗
NASA NTRS2018

Multi-Star Wavefront Control for the Wide-Field Infrared Survey Telescope

The Wide-Field Infrared Survey Telescope (WFIRST) is planned to have a coronagraphic instrument (CGI) to enable high-contrast direct imaging of exoplanets around nearby stars. The majority of nearby FGK stars are located in multi-star systems, including the Alpha Centauri stars which may represent the best quality targets for the CGI on account of their proximity and brightness potentially allowing the direct imaging of rocky planets. However, a binary system exhibits additional leakage from the off-axis companion star that may be brighter than the target exoplanet. Multi-Star Wavefront Control (MSWC) is a wavefront-control technique that allows suppression of starlight of both stars in a binary system thus enabling direct imaging of circumstellar planets in binary star systems such as Alpha Centauri. We explore the capabilities of the WFIRST CGI instrument to directly image multi-star systems using MSWC. We consider several simulated scenarios using the WFIRST CGI's Shaped Pupil Coronagraph Disk Mask. First, we consider close binaries such as Mu Cassiopeia that require no modifications to the WFIRST CGI instrument and can be implemented as a purely algorithmic solution. Second, we consider wide binaries such as Alpha Centauri that require a diffraction grating to enable suppression of the off-axis starlight leakage at Super-Nyquist separations. We demonstrate via simulation dark holes in 10 percent broadband compatible with the WFIRST CGI.

Sirbu, Dan↗
NASA NTRS2017

Techniques for High Contrast Imaging in Multi-Star Systems II: Multi-Star Wavefront Control

Direct imaging of exoplanets represents a challenge for astronomical instrumentation due to the high-contrast ratio and small angular separation between the host star and the faint planet. Multi-star systems pose additional challenges for coronagraphic instruments because of the diffraction and aberration leakage introduced by the additional stars, and as a result are not planned to be on direct imaging target lists. Multi-star wavefront control (MSWC) is a technique that uses a coronagraphic instrument's deformable mirror (DM) to create high-contrast regions in the focal plane in the presence of multiple stars. Our previous paper introduced the Super-Nyquist Wavefront Control (SNWC) technique that uses a diffraction grating to enable the DM to generate high-contrast regions beyond the nominal controllable region. These two techniques can be combined to generate high-contrast regions for multi-star systems at any angular separations. As a case study, a high-contrast wavefront control (WC) simulation that applies these techniques shows that the habitable region of the Alpha Centauri system can be imaged reaching 8 times 10(exp -9) mean contrast in 10 percent broadband light in one-sided dark holes from 1.6-5.5 lambda (wavelength) divided by D (distance).

Sirbu, D.↗
NASA NTRS2014

The Miniature Radio Frequency Instruments (Mini-RF) Global Observations of Earth's Moon

Radar provides a unique means to analyze the surface and subsurface physical properties of geologic deposits, including their wavelength-scale roughness, the relative depth of the deposits, and some limited compositional information. The NASA Lunar Reconnaissance Orbiter's (LRO) Miniature Radio Frequency (Mini-RF) instrument has enabled these analyses on the Moon at a global scale. Mini-RF has accumulated 67% coverage of the lunar surface in S-band (12.6 cm) radar with a resolution of 30 m/pixel. Here we present new Mini-RF global orthorectified uncontrolled S-band maps of the Moon and use them for analysis of lunar surface physical properties. Reported here are readily apparent global- and regional-scale differences in lunar surface physical properties that suggest three distinct terranes, namely: a (1) Nearside Radar Dark Region; (2) Orientale basin and continuous ejecta; and the (3) Highlands Radar Bright Region. Integrating these observations with new data from LRO's Diviner Radiometer rock abundance maps, as well Clementine and Lunar Prospector derived compositional values show multiple distinct lunar surface terranes and sub-terranes based upon both physical and compositional surface properties. Previous geochemical investigations of the Moon suggested its crust is best divided into three to four basic crustal provinces or terranes (Feldspathic Highlands Terrane (-An and -Outer), Procellarum KREEP Terrane, and South Pole Aitken Terrane) that are distinct from one another. However, integration of these geochemical data sets with new geophysical data sets allows us to refine these terranes. The result shows a more complex view of these same crustal provinces and provides valuable scientific and hazard perspectives for future targeted human and robotic exploration.

Radar observations↗
NASA NTRS2012

Radar Scattering and Block Size Properties of Lunar Crater Ejecta From Mini-RF and LROC NAC Data

A major objective of the Mini-RF experiment is to distinguish lunar surfaces that may contain water/ice deposits [1,2]. Better understanding of the backscattering properties of craters of varying age and size is crucial for interpreting data received from the Mini-RF. The Mini-RF transmits a circularly polarized RF electromagnetic energy and coherently receives orthogonal linear polarization echoes [1]. The Mini- RF maps in two separate bands ( =12.6 and 4.5 cm) at a high resolution mode of 30 m/pixel [1]. Given the variables mentioned, the four stokes parameters are reconstructed. The Circular Polarization Ratio (CPR) is calculated for the purposes of understanding subsurface and surface roughness. The CPR is determined from reflections acquired from the ratio of power of the transmitted radio wave in same sense to the reflected radio wave in the opposite sense [1]. Ice in the permanently shadowed regions (PSRs) would be transparent to radar, but the inclusions of materials and imperfections would cause the radio wave to reflect multiple times [3], enhancing the number of same sense reflections and increasing the CPR. In addition, ice also displays the coherent backscatter opposition effect (CBOE), an interferrometric addition of same sense backscatter that further increases the CPR of ice targets [7]. High CPR values also correlate to multiple reflections and are typically associated with very rough surfaces [3]. The average dry lunar surface has a CPR in the range of 0.2-0.4 at 48deg incidence [3]. The purpose of this study is to begin to quantify degrees of surface wavelength-scale roughness with CPR and to understand how such surface roughness is created and gradually destroyed by erosion on the lunar surface. Another goal is to identify and isolate the possible causes of high CPR within the shadowed areas of anomalous polar craters [3]. All the studied craters are non-polar, so that we can see into their interiors in NAC images. The idea is to understand what controls blockiness in these craters so that we can rule out rocks (and rule in ice) for the anomalous polar dark ones [3].

Spudis, P. D.↗
NASA NTRS1996

Intergalactic Hydrogen Clouds at Low Redshift: Connections to Voids and Dwarf Galaxies

We provide new post-COSTAR data on one sightline (Mrk 421) and updated data from another (I Zw 1) from our Hubble Space Telescope (HST) survey of intergalactic Ly(alpha) clouds located along sightlines to four bright quasars passing through well-mapped galaxy voids (16000 km/s pathlength) and superclusters (18000 km/s). We report two more definite detections of low-redshift Ly(alpha) clouds in voids: one at 3047 km/s (heliocentric) toward Mrk 421 and a second just beyond the Local Supercluster at 2861 km/s toward I Zw 1, confirming our earlier discovery of Ly(alpha) absorption clouds in voids (Stocke et al., ApJ, 451, 24). We have now identified ten definite and one probable low-redshift neutral hydrogen absorption clouds toward four targets, a frequency of approximately one absorber every 3400 km/s above 10(exp 12.7/sq cm column density. Of these ten absorption systems, three lie within voids; the probable absorber also lies in a void. Thus, the tendency of Ly(alpha) absorbers to 'avoid the voids' is not as clear as we found previously. If the Ly(alpha) clouds are approximated as homogeneous spheres of 100 kpc radius, their masses are approximately 10(exp 9)solar mass (about 0.01 times that of bright L* galaxies) and they are 40 times more numerous, comparable to the density of dwarf galaxies and of low-mass halos in numerical CDM simulations. The Ly(alpha) clouds contribute a fraction Omega(sub cl)approximately equals 0.003/h(sub 75) to the closure density of the universe, comparable to that of luminous matter. These clouds probably require a substantial amount of nonbaryonic dark matter for gravitational binding. They may represent extended haloes of low-mass protogalaxies which have not experienced significant star formation or low-mass dwarf galaxies whose star formation ceased long ago, but blew out significant gaseous material.

Shull, J. Michael↗
NASA NTRS2005

Lunar and Planetary Science XXXVI, Part 15

Contents include the following: Impact Metamorphism of Subsurface Organic Matter on Mars: A Potential Source for Methane and Surface Alteration. Preliminary Study of Polygonal Impact Craters in Argyre Region, Mars. Geochemistry of the Dark Veinlets in the Granitoids from the Souderfjarden Impact Structure, Finland: Preliminary Results. An Experimental Method to Estimate the Chemical Reaction Rate in Vapor Clouds: An Application to the K/T Impact. Study of the Apollo 16 Landing Site: Re-Visit as a Standard Site for the SELENE Multiband Imager. First X-Ray Observation of Lunar Farside from Hayabusa X-Ray Spectrometer. Lunar X-Ray Fluorescence Spectrometry from SELENE Lunar Polar Orbiter. Origin and Thermal History of Lithic Materials in the Begaa LL3 Chondrite. Evidence of Normal Faulting and Dike Intrusion at Valles Marineris from Pit Crater Topography. Evidence of Tharsis-Radial Dike Intrusion in Southeast Alba Patera from MOLA-based Topography of Pit Crater Chains. Are They Really Intact? Evaluation of Captured Micrometeoroid Analogs by Aerogel at the Flyby Speed of Stardust. Numerical Simulations of Impactor Penetration into Ice-Over-Water Targets. A Probable Fluid Lava Flow in the Hebes Mensa (Mars) Studied by HRSC Images. New Drill-Core Data from the Lockne Crater, Sweden: The Marine Excavation and Ejection Processes, and Post-Impact Environment. Cross-Sectional Profile of Baltis Vallis Channel on Venus: Reconstruction from Magellan SAR Brightness Data.

Source record↗
NASA NTRS1996

The Response of Disks to Oscillatory Modes in Galaxies

Recent studies suggest that galaxies can oscillate in normal modes with essentially no damping over a Hubble time. These modes may play an important role in the structure and evolution of disk/halo systems. Motivated by the possibility that normal mode oscillations exist in real galaxies, we are investigating the response of galactic disks to halo oscillations. The goal of these investigations is to ascertain whether or not observational signatures exist for such oscillations. Our approach is to perform numerical experiments on the response of a self-gravitating disk to a time-varying halo potential. We assume that a significant fraction of the mass in a galaxy is in a dark halo. The halo oscillates and the luminous disk material responds to these oscillations. Preliminary results are reported for disks embedded in a radially oscillating gravitational potential. The equilibrium initial disk is represented by an exponential density profile. Considerable care was taken to build an initial disk model that was "stable" over long time scales. A control experiment was run with the disk in a static halo potential. The disk responds to the time-varying potential by developing a ring structure, which forms and disappears during each halo oscillation cycle. The density of stars becomes depressed in an annular region at the radius where the disk epicycle frequency is equal to the halo oscillation period. This pattern of response persists over time periods approaching a Hubble time. In the oscillating potential, a bar develops in the inner disk. This bar is absent when the halo remains static. Specific targets of this study include the implications for large-scale disk structure, the gas dynamical response of the interstellar medium in such systems, and the inflow of material into the central regions of the galaxy.

Smith, Bruce F.↗
NASA NTRSDate not supplied

NASA LSII Lunar Simulant Project

Introduction: America has entered a new era of exploration. NASA’s Artemis program will lead humanity forward to the Moon and prepare us for the next giant leap, the exploration of Mars [1]. To champion technologies needed to live on and explore the Moon, NASA’s Space Technology Mission Directorate (STMD) established the Lunar Surface Innovation Initiative (LSII)[2].LSII's technology development portfolio includes: Utilizing the Moon’s resources; Establishing sustainable surface power; Building machinery and electronics that work in extreme environments, like super-chilly permanently shadowed craters; Mitigating lunar dust; Carrying out surface excavation, manufacturing and construction duties; and Extreme access which includes navigating and exploring the surface/subsurface. To support the development and testing of these technologies, LSII created the lunar simulant project, to create and/or acquire low-, medium-and high-fidelity lunar simulants to match the needs of STMD projects at all levels of technology readiness levels (TRL), as well as other NASA programs. There is not one bulk lunar simulant that will satisfy the needs of all projects. NASA's Approach to Simulants: Just as LSII's activities are being implemented through a combination of unique NASA work and public-private partnerships, NASA will work with commercial simulant providers to acquire simulants that meet NASA's needs. If warranted, NASA will develop simulants using government agencies, as was done with the NASA/USGS Lunar Highlands Type (NU-LHT)series of lunar simulants [3].NASA is also collaborating with the Johns Hopkins University Applied Physics Laboratory(JHUAPL) Lunar Surface Innovation Consortium (LSIC) in the development and characterization of lunar simulants [4]. Within NASA, a small team (< 10 people) is coordinating simulant activities across the agency, with team members located at several NASA centers. The overall objective of the project is to procure lunar simulants in sufficient amounts for earth-based testing of subsystems and systems in a variety of environments (i.e., laboratory, high-bay, thermal-vacuum chambers), required for Artemis missions to the Moon, as well as other missions carrying NASA lunar payloads, such as the Commercial Lunar Payload Services (CLPS)program [5]. Lunar Highlands Simulant: NASA's Artemis Program is targeting the lunar south pole region for initial human missions and the Artemis Base Camp. Hence, the LSII lunar simulant project is currently focusing on the mineralogy and properties of lunar highlands regolith [6 and 7]. Plagioclase-rich rocks (e.g., anorthosite, norite) are the dominant constituent in highlands simulants, with Shawmere, Stillwater, and White Mountain anorthosites being used in commercially available simulants. However, because these feedstocks are terrestrial in nature, they include hydrated minerals, carbon-bearing minerals, and other chemical signatures that are not present on the Moon, and these minor mineral assemblages need to be taken into account when trying to understand test procedures and results. Glass Component: While much attention has been placed on the rock/mineral component of lunar simulants, glass is just as important when creating simulants. The glass component in lunar regoliths is often greater than 50% by volume [8]. This component includes impact melt glass, dark matrix breccias, and agglutinates. However, this component is difficult, time-consuming and expensive to make. Most lunar simulants, past and current, have relied on basaltic cinder as a feedstock for glass. Getting better glass components at a lower cost, particularly agglutinates and glass with an anorthositic composition is a near-term objective that the NASA simulant project is trying to address . Characterization: It is extremely important for lunar simulants to be characterized by several analytical methods. Gruener et al. [9] and JHUAPL LSIC [10] conducted initial assessments of some of the commercially available simulants in 2019 and early 2020, before the global pandemic. Further analyses are needed to better quantify important parameters such as, modal mineralogy and glass content, particle shape, and particle size distribution. These quantified results can then be used in determining figures of merit (FOM) that show how well simulants compare to lunar regolith [11 and 12].

J E Gruener↗
NASA NTRSDate not supplied

NASA's Habitation Development Status: Current Concepts and ISRU Opportunities

Introduction: The National Aeronautics and Space Administration (NASA) is embarking on a bold journey to return humankind to the Moon and onward to Mars with innovative commercial, international, and academic partnerships [1]. Under the Artemis series of missions, NASA seeks to establish sustained human exploration of deep space through an objectives-based approach [2]. This approach drives the identification of needed system functionality and the current and future capabilities which will eventually allow humanity to sustainably live beyond Earth. Providing evolvable and scalable habitation is a cornerstone function that calls for the collection and integration of current, developmental, and future technologies that can meet near-term exploration needs while growing into long-term sustained presence. NASA is advancing in-space habitation through its Next Space Technologies for Exploration Partnerships (NextSTEP) model while designing lunar, Mars transit, and Mars surface habitat government reference concepts for Artemis missions. These efforts have unveiled possible near-term opportunities for the in-space resource utilization community if human habitation is considered a future customer of space resources. NextSTEP Habitation Development: NASA is closely working with commercial partners under its NextSTEP Appendix A model to advance habitation systems in the arena of inflatable and composite habitation structures. Such efforts promise efficiencies in volumetric packaging and overall spacecraft mass respectively. Recent testing by commercial partners have helped to quantify possible failure mechanisms for inflatable structures while advancing their technology towards eventual flight certification. The advancement of such Class II habitation structures, in which the habitat is only fully deployed once in-space or on a planetary surface [3], is critical to providing increased habitable volume for long-duration missions with no additional mass penalties. The progression of such technology is infused into NASA’s government reference concepts for notional deep space habitation concepts. Current Government Reference Concepts: To best inform the formulation of future collaborative solicitations, NASA employs the practice of internally developing reference concepts for future exploration elements. These concepts aid in identifying the functions and capabilities needed to complete NASA missions as well as feasible solutions within the timeframe needed. Government reference concepts for a lunar Surface Habitat, Mars Transit Habitat, and Mars Sur-face Habitat are continuously being developed and updated to better guide the Agency’s overall exploration architecture. Lunar Surface Habitat. As NASA returns to the Moon, it is evaluating possible lunar surface habitation concepts. The Surface Habitat (SH) reference concept entails a hybrid metallic-inflatable structure capable of initially housing two crew for surface stays of up to 30 days in duration [4]. While initial missions may span ~7 days in duration, consideration is being given to expanding SH’s capability to support a crew of four for up to 60 days over its 15-year design life [5]. Functionally, the SH serves as a ‘hub’ for all Artemis crewed surface operations, providing internal volume for maintenance, medical, logistics, science utilization, and extravehicular activity (EVA) support in addition to core habitation functionality such as environmental control and life support (ECLS) and power generation and distribution among many others. Additionally, NASA has entered a study agreement with the Italian Space Agency (Agenzia Spaziale Italiana – ASI) to investigation a possible Multi-Purpose Habitat (MPH) as an additional or augmenting habit-able element for the lunar surface [6]. Mars Transit Habitat. NASA’s current architectural concept for initial human missions to Mars entails the utilization of a transit habitat (TH) to transport a four-person crew to and from Mars orbit, departing from and returning to a lunar near-rectilinear halo orbit (NRHO), over the course of a ~1,200-day mission [5]. While holding a similar 15-year design lifetime, TH will also support a series of analog mission activities in NRHO to gradually test the systems and interaction with lunar surface elements, some of which may be adapted for Mars surface exploration. Holding similar functional capabilities as SH, TH is sized to support much longer durations in space and greater logistical independence. Mars Surface Habitat. NASA is still exploring the concept of operations for initial crewed missions to Mars. As such, the Mars Surface Habitat (MSH) concept is still in its infancy as options for mobile, pressurized habitation and stationary habitats are being explored. It is expected MSH will leverage heavily from the lunar SH and possible lunar pressurized rover, however the very different Martian environment will likely necessitate modifications. ISRU Opportunities: Despite the advancements under NASA’s NextSTEP habitation work and continually optimized reference concepts, NASA is facing near-term mass and power challenges that may create opportunities to the ISRU community by providing yet another possible customer for space resources. While NASA desires to use regenerative ECLS systems (ECLSS) for all habitation concepts, their operation comes with initial mass penalties and maintenance overheads when compared to simpler open-loop architectures. Because of this, NASA is currently pro-posing an open-loop, consumables-based architecture for its surface habitats to achieve initial launch and delivery lander mass targets while scarring for the in-corporation of regenerative ECLSS to meet longer mission durations and sustained presence. With such an architecture, oxygen and potable water are needed consumables, which initial ISRU systems may be able to provide in a pilot capacity. Although the TH is expecting to utilize regenerative ECLSS, advancements in lunar surface-based ISRU and possible re-supply of spacecraft in lunar or Mars orbit could significantly reduce the logistical need for ECLSS related spares on TH and possibly allow a similar open-loop and consumables-based architecture. Table 1 Notional ECLSS consumables per mission use for SH and TH [5]. SH (28-day) Open Loop: Water (kg) 288 | Oxygen (kg) 30 TH (1110-day) Closed-Loop: Water (kg) 182 | Oxygen (kg) 123 In addition to ECLSS mass concerns, the SH is facing challenges with energy storage to support operations over periods of darkness exceeding 100 hours. Both battery and fuel cell-based power architectures are being traded, opening options for external power generation and energy storage. One possibility is ISRU-produced H2 and O2 feeding external primary fuel cell systems which could supplement habitation power generation while reducing initial mass and volume until much more powerful fission power systems might be deployed. Conclusion: Significant advancements are being made in evolvable habitation concepts that span from near-term technologies, such as inflatable structures under NextSTEP, to potentially revolutionary capabilities like the lunar surface construction as funded through the Moon-to-Mars Planetary Autonomous Construction Technologies (MMPACT) project [7]. As NASA investigates both heritage capabilities and rap-idly advancing, disruptive technologies, there are likely many near-term opportunities for initial ISRU capabilities to significantly aid human habitation and increase self-sufficiency beyond Earth.

habitation↗
NASA NTRSDate not supplied

Assessing Organic Preservation and the Implications for Potential Biosignatures in the Bastide Member of the Séítah Formation, Jezero Crater

Introduction: Olivine has the highest CO2 trapping potential of ultramafic minerals, due to its rapid rate of dissolution and high percentage of divalent cations/unpolymerized silicate tetrahedra [1]. It generates divalent carbonates from CO2 and sequesters CO2 into the mineral matrix of the target lithology. The co-occurrence of olivine and carbonate within abraded targets from the Bastide Member of the Séítah Formation (Fm) of the Jezero crater floor [2] suggests the carbonation of olivine occurred within the mineral matrix hosted in a subsurface system. Hydrothermal origins for the subsurface system are hypothesized from orbital data [3]. This is supported by the detection of hydration features within the rock as well as the carbonate features are solely detected within the abrasion patch but not the rock’s surface. Organic preservation potential of abrasion patches: We incorporated the SHERLOC/WATSON results acquired from the Dourbes, Garde, and Quartier abrasion patches in the Séítah Fm to investigate the organomineral associations, and determine the biosignature preservation potential of these rocks. Dourbes is dominated by olivine and has minor amounts of carbonate, hydrated Ca-sulfate, and amorphous or microcrystalline silicate. Fluorescence features (330-340 nm) are detected in discrete locales and could be consistent with double ring aromatic organic molecules; yet, these features do not appear to be associated with an identified mineral phase. Dark subhedral to euhedral olivine grains within the Garde abrasion patch often co-occur with carbonate-consistent spectral signatures in all analyzed scans. The availability of Fe2+ is a known influence on olivine dissolution rates [1] and SuperCam estimates of the olivine composition (Forsterite-60 average for Sols 202-234) may thereby provide a constraint on the carbonation extent. Carbonated olivine phenocrysts within the matrix may be due to aqueous alteration, as the carbonation of nodules is consistent with observations in other hydrothermal systems and within Martian meteorites (ALH84001) [4]. In comparison, the Quartier abrasion patch represents an extensively altered endmember within the Bastide Member of the Séítah Fm. It contains a fluorescence doublet at 305/325 nm that coexists with multiple species of Na-sulfate and Mg-sulfate, Mg-carbonates, olivine [5]. Aqueous alteration and implications for habitability: The identification of primary and secondary mineral phases observed in the Bastide Member suggests the release of cations from primary ultramafic minerals through aqueous alteration. Within Garde, the carbonate detected appears to be Mg-rich and likely formed from the in situ alteration of Mg-rich olivine within the region as carbonate has only been detected within the rock via in situ analysis. Carbonates derived from abiotic and biotic reactions preserve biosignatures (i.e. indices of habitability) on Earth. The detected carbonate phase found in association with fluorescent features within the rock matrix may also indicate potential organic compounds preserved in a putative hydrothermal system. Fluorescent features (~330 nm) are unique to Garde and Dourbes, though they are co-located to carbonate signatures solely within Garde, and between the light toned minerals. Identification of these fluorescent features may be consistent with 1-2 ring aromatic compounds. The limit of detection for Raman is multiple orders of magnitude greater than the limit of detection required for fluorescence [6]. Implications for provenance: Hydrothermal systems represent disequilibrium chemical conditions that are hypothesized to have supported the emergence of life and also preserve ancient carbon within precipitated carbonates [7]. Hydrothermal system associated carbonates are capable of preserving biosignatures up to an estimated ~3.77 – 4.28 Gya [8]. Thus, carbonated olivine found within the Séítah Fm may represent a high-potential biosignature preserving environment on Mars. The formation of carbonates by an aqueous alteration process, such as carbonation of olivine is also consistent with hypotheses for carbonate within the greater regional-olivine bearing unit [2,3], which contains Garde, Dourbes, and Quartier. Acknowledgments: This work was carried out at the Jet Propulsion Laboratory, The California Institute of Technology under a contract from NASA. References: [1] Wood et al., (2019) ES&T, 6, 10. [2] Stack, K. et al., (2020) Space Sci Rev, 216, 127. [3] Tarnas, J. et al., (2021) JGR: Planets, 126, 11. [4] Steele et al., (2007) Meteorit. Planet. Sci., 42, 9. [5] Murphy, A.E. et al., (2022) LPSC [6] Bhartia et al., (2021) Space Sci Rev, 217, 58. [7] Luther (2021) GRL, 48, e2021GL094869. [8] Dodd et al., (2017) Nature, 543, 60-64

E L Cardarelli↗
NASA NTRS1999

Development of Gravity Sensitive Plant Cells (Ceratodon) in Microgravity

Protonemata of the moss Ceratodon are tip-growing cells that grow up in the dark. This cell type is unique compared to cells in almost any other organism, since the growth of the plant cell itself is completely oriented by gravity. Thus, both the processes of gravity sensing and the gravity response occur in the same cell. Gravity sensing appears to rely upon amyloplasts (starch-filled plastids) that sediment. This sedimentation occurs in specific zones and plastid zonation is complex with respect to plastid morphology, distribution, and gravity. Microtubules restrict the extent of plastid sedimentation (i.e., they are load-bearing). Light also is important since apical cells have a phytochrome-based positive phototropism, light quality influences plastid zonation and sedimentation (photomorphogenesis), and red light suppresses gravitropism at higher but not lower light intensities. Many of these processes were examined in a 16 day spaceflight experiment, "SPM-A" space moss" or "SPAM)) on STS-87 that landed in December, 1997. The work described here involves the definition of a second flight experiment that builds upon the data and questions arising from STS-87. Effort was directed towards further definition of an experiment for the Shuttle (dubbed "SOS" for "Son of SPAM"). Our current target is STS 107 that is scheduled to fly in January 2001. This definition addressed two goals of the STS107 experiment. The goals of the current experiment were to determine whether the cytoskeleton plays a role in maintaining and generating an apical (non-random) plastid distribution in microgravity and to determine the development and extent of clockwise spiral tip-growth in microgravity.

Sack, Fred D.↗
NASA NTRS2011

Space Weathering Impact on Solar System Surfaces and Planetary Mission Science

We often look "through a glass, darkly" at solar system bodies with tenuous atmospheres and direct surface exposure to the local space environment. Space weathering exposure acts via universal space-surface interaction processes to produce a thin patina of outer material covering, potentially obscuring endogenic surface materials of greatest interest for understanding origins and interior evolution. Examples of obscuring exogenic layers are radiation crusts on cometary nuclei and iogenic components of sulfate hydrate deposits on the trailing hemisphere of Europa. Weathering processes include plasma ion implantation into surfaces, sputtering by charged particles and solar ultraviolet photons, photolytic chemistry driven by UV irradiation, and radiolytic chemistry evolving from products of charged particle irradiation. Regolith structure from impacts, and underlying deeper structures from internal evolution, affects efficacy of certain surface interactions, e.g. sputtering as affected by porosity and surface irradiation dosage as partly attenuated by local topographic shielding. These processes should be regarded for mission science planning as potentially enabling, e.g. since direct surface sputtering, and resultant surface-bound exospheres, can provide in-situ samples of surface composition to ion and neutral mass spectrometers on orbital spacecraft. Sample return for highest sensitivity compOSitional and structural analyses at Earth will usually be precluded by limited range of surface sampling, long times for return, and high cost. Targeted advancements in instrument technology would be more cost efficient for local remote and in-situ sample analysis. More realistic laboratory simulations, e.g. for bulk samples, are needed to interpret mission science observations of weathered surfaces. Space environment effects on mission spacecraft and science operations must also be specified and mitigated from the hourly to monthly changes in space weather and from longer term (e.g., solar cycle) evolution of space climate. Capable instrumentation on planetary missions can and should be planned to contribute to knowledge of interplanetary space environments. Evolving data system technologies such as virtual observatories should be explored for more interdisciplinary application to the science of planetary surface, atmospheric, magnetospheric, and interplanetary interactions.

Cooper, John F.↗
NASA NTRS1998

Proposed Mars Surveyor Landing Sites in Northern Meridiani Sinus, Southern Elysium Planitia, and Argyre Planitia

Our objective is to propose two landing sites that the Mars Surveyor 2001 Lander and Athena Rover could go to on Mars that should meet the safety requirements of the spacecraft landing system and optimize surface operations (chiefly driven by power and communications requirements). An additional site within Argyre Planitia, initially proposed by Parker to the Mars Surveyor Landing Site program, is also proposed for potential consideration for post-2001 missions to Mars, as it is well outside the current latitude limits for the Athena Rover. All three sites are designed to be situated as close to a diversity of geologic units within a few kilometers of the landing site so that diversity can be placed in a geologic context. This objective is very different from the Mars Pathfinder requirement to land at a site with a maximum chance for containing a diversity of rocks within a few tens of meters of the lander. That requirement was driven by the Sojourner mobility limit of a few tens of meters. It can be argued that the Athena project, with its much larger mobility capability, might actually want to avoid such a site, because placing collected samples in geologic context would be difficult. While it has been argued, both before and after the Mars Pathfinder landing, that the provenance for local blocks may be determined by orbiter spectra, primarily from the MGS TES instrument, our ability to do so has yet to be demonstrated. Indeed, several months after conclusion of the Pathfinder mission, we have yet to reach a consensus on the composition of local materials. Our primary data set for selecting a landing site within the latitude and elevation constraints of the 2001 mission is the Viking Orbiter image archive. The site must be selected to place the landing ellipse so as to avoid obvious hazards, such as steep slopes, large or numerous craters, or abundant large knobs. For this purpose, we chose a resolution limit of better than 50 m/pixel. This necessarily excludes from the present study images from current and future orbiter spacecraft, until such data does become readily available. Within each proposed region, it may be possible to identify additional sites once these data become available. Second, the fine-component thermal inertia data, should be greater than about 5 or 6 cgs Units (10(exp -3) cal/sq cm s(exp -0.5)/K). Low thermal inertias imply dusty environments, which could pose a mobility hazard. Similarly, the albedo of the site should not be particularly high, which would also suggest dusty surfaces. Low albedos are preferred, as they often coincide with low Viking red:violet ratios and indicate less dusty surfaces. Next, the Modeled Block Abundance should also not be too high or too low. Based on the Viking Lander and Mars Pathfinder experiences, percentages of blocks should be on the order of 5-25%. Too many blocks could pose a hazard to the landing and mobility. Too few blocks could also indicate a dusty surface. Primary Landing Site: Northern Meridiani Sinus (Proposed by T. J. Parker and K., S. Edgett) Vital Statistics: (1) Latitude, Longitude: 0-3 N, 350-2 W. *Elevation (Viking): about0.5-1.5 Ian. (2) Viking Orbiter Image coverage: Excellent coverage by 15 - 25 m/pixel images (orbits 709A and 410B). Possible stereo coverage in region where two orbits overlap (probably small parallax angle, as these orbits are not listed in NASA Contractor Report 3501) (3) Albedo: about .18 -.26 (4) Block Abundance: 5-26% (5)Fine-Component Thermal Inertia: 5-9 cgs units This region consists of bright deposits similar to those described by Edgett et al, that also lie within a prominent dark albedo region. These deposits are flat-lying, to such a degree that they ramp against topography rather than draping over it. This led Edgett and Parker to suggest that they may be subaqueous sediments, possibly lacustrine or marine evaporites, laid down sometime from the late Noachian to middle Hesperian (age determination pending crater counts). A contact between this material and elevated, dissected highlands to the south was identified , and is described by Edgett et al. Our desire in proposing this landing site is to sample the edge of this deposit where it has been exposed through etching, presumably eolian deflation (the deposit, though in the highlands, is itself only lightly to moderately cratered). This should enable access to in situ stratigraphy. The actual landing site will be selected where slopes are not expected to be steep, such that the rover itself should be able to traverse them and sample layered materials on the way, either up or down the slope. Perhaps due to uncertainties at this time as to the friability or meter-scale roughness of the deposit, it might make sense to place the landing ellipse on the exhumed highland surface adjacent to the deflated margin of the deposit and plan on driving to the deposit rather than landing on it and driving downslope. This should also enable imaging the margin for evidence of layering should it prove too difficult to climb. A target ellipse on the highland surface should also allow Athena access to ancient Noachian highland materials, particularly if placed near crater ejecta or an inlier of knobby material. Secondary Landing Site: Southern Elysium Planitia (Proposed by T. J. Parker) Vital Statistics: (1) Latitude, Longitude: 1.5-3.5 S, 195-198 W. (2) Elevation (Viking): -1.0 km. (3) Viking Orbiter Image coverage: Excellent coverage by 15 - 25 m/pixel images (orbit 725). Possible stereo coverage between images from beginning and end of orbit that overlap (probably small parallax angle) (4) Albedo: about .27-.28 (5) Block Abundance: 4-7% (6) Fine-Component Thermal Inertia: about 3 cgs units This region consists of eroded knobby material, probably of Noachian age, though much of the crater population has been destroyed, that is onlapped at a sharp contact by an extensive plains unit in southern Elysium Planitia that is Amazonian in age. The plains materials have been attributed to unusually low-viscosity flood lavas from fissures south of the Elysium volcanic rise, or to lacustrine materials associated with a large, Amazonian lake at the source of Marte Vallis. Parker and Schenk presented evidence in support of the latter interpretation, though they attributed the putative shore morphology to an embayment of a northern plains ocean into the southern Elysium region. Detailed examination of the margin of the deposit, showing erosion, not simply burial, of small crater rims and fluidized ejecta blankets, also points to lacustrine or marine sedimentation rather than volcanic plains burial. The plains surface exhibits a "crusty" appearance that many researchers have attributed to pressure ridges in lava flows. In a lacustrine context, they also resemble pressure ridges in desiccated evaporite deposits and salt-rimmed pools (now dry) similar in scale and morphology to spectacular, hundred meter-scale pool rims in alkaline Lake Natron, East African Rift. The eroded highland margin surface adjacent to these plains appears to be fairly smooth, even at 15 m/pixel. Isolated knob inliers are scattered from a few kilometers to several tens of "kilometers apart. Heights of the knobs have not been measured yet but, based on experience with similar features in the Pathfinder landing ellipse, are probably typically on the order of several tens of meters high and smaller, though some of the largest knobs in the region are probably up to a few hundred meters high. Two craters larger than a kilometer in diameter, with fluidized deposits, lie nearby the proposed landing site. Very high-resolution images from MOC should help to determine whether a landing site navigable by the Athena rover could be placed in this region. The space between knobs and craters is large enough to enable placement of a target landing ellipse between them but still provide access to one or more of them and to the margin of the Elysium plains material. Post-2001 Mars Surveyor Landing Site: Argyre Planitia (Proposed by T. J. Parker) Vital Statistics: (1) Latitude, Longitude: 55-56 S, 41-43 W. (2) Elevation (Viking): 1.0 km. (3) Viking Orbiter Image coverage: Excellent coverage by 40 m/pixel images (orbits 567B, 568B, and 569B). Excellent stereo coverage with large parallax angles over the entire landing site region, and much of central and southern Argyre. (4) Albedo: about .23-.24 (5) Block Abundance: No data (6) Fine-Component Thermal Inertia: No data The floors of both the Argyre and Hellas basins contain etched layered materials that are probably thick accumulations of channel or lacustrine sediments. The deposits in Hellas are much more eroded than those in Argyre, and Hellas lacks a channel outlet. Argyre is unique in that Uzboi Vallis flowed out of the basin, requiring overflow of a standing body of water within Argyre. This makes it the largest impact basin on Mars with channels both draining into it and flowing out from it. Hellas' channels may be catastrophic flood channels, whereas Argyre was fed by modest-scale valley networks, though the outlet at Uzboi Vallis was a catastrophic flood Highland craters and basins of this kind should be high-priority landing targets for missions intended to focus on the search for either prebiotic organic materials or even simple fossil microorganisms. Basins with internally-draining valley networks should be preferred over flood channels, as they could have provided the long-term influx of water favorable to the origin of life. (Catastrophic floods are not conducive to fossil preservation, due to their very short durations and high transportation energies). They also afford an opportunity to study the evolution of the planet's climate and volatiles during the period of time between the late Noachian and early Hesperian, when a drastic change from a proposed early warm, wet climate to one more closely resembling the modern environment is thought to have occurred. Large basin

Parker, T. J.↗
NASA NTRS2016

Characterizing Rocky and Gaseous Exoplanets with 2 m Class Space-based Coronagraphs

Several concepts now exist for small, space-based missions to directly characterize exoplanets in reflected light. While studies have been performed that investigate the potential detection yields of such missions, little work has been done to understand how instrumental and astrophysical parameters will affect the ability of these missions to obtain spectra that are useful for characterizing their planetary targets. Here, we develop an instrument noise model suitable for studying the spectral characterization potential of a coronagraph-equipped, space-based telescope. We adopt a baseline set of telescope and instrument parameters appropriate for near-future planned missions like WFIRST-AFTA, including a 2 m diameter primary aperture, an operational wavelength range of 0.4–1.0 μm, and an instrument spectral resolution of λ/Δλ =70, and apply our baseline model to a variety of spectral models of different planet types, including Earth twins, Jupiter twins, and warm and cool Jupiters and Neptunes. With our exoplanet spectral models, we explore wavelength-dependent planet–star flux ratios for main-sequence stars of various effective temperatures and discuss how coronagraph inner and outer working angle constraints will influence the potential to study different types of planets. For planets most favorable to spectroscopic characterization—cool Jupiters and Neptunes as well as nearby super-Earths—we study the integration times required to achieve moderate signal-to-noise ratio spectra. We also explore the sensitivity of the integration times required to either detect the bottom or presence of key absorption bands (for methane, water vapor, and molecular oxygen) to coronagraph raw contrast performance, exozodiacal light levels, and the distance to the planetary system. Decreasing detector quantum efficiency at longer visible wavelengths makes the detection of water vapor in the atmospheres of Earth-like planets extremely challenging, and also hinders detections of the 0.89 μm methane band. Additionally, most modeled observations have noise dominated by dark currents, indicating that improving CCD performance could substantially drive down requisite integration times. Finally, we briefly discuss the extension of our models to a more distant future Large UV-Optical-InfraRed (LUVOIR) mission.

Astrobiology↗
NASA NTRSDate not supplied

New Mastcam Multispectral Rock Classes in Sulfate-Bearing Strata, Gale Crater, Mars

Orbital data of Gale Crater, Mars has identified a transition in the stratigraphy of Mt. Sharp indicating an environmental change from a wetter one that accommodated clay mineral formation to a drier environment that led to the precipitation of sulfates. Mt. Sharp is not the only location on Mars for which this transition has been observed which suggests a global environmental change around the Noachian-Hesperian transition. Also visible from orbit is a dark-toned marker band that lies within the sulfate-bearing strata hypothesized to be a volcanic ash deposit. The Mars Science Laboratory (MSL) Curiosity rover is currently exploring this region of Mt. Sharp. In-situ analyses by the rover show changes in morphology and chemistry between the sulfate-bearing layers below and above the marker band and the marker band itself. The MSL instrument payload includes the Mast Camera (Mastcam), which collects multispectral images to provide context for other instruments and broad mineralogic interpretations. In addition to mafic Fe-bearing minerals, Mastcam is sensitive to oxides and some hydrated minerals, important indicators of alteration. In our previous work, we compiled a database of Mastcam spectra through Curiosity’s exploration of Vera Rubin ridge (sols 0-2302), from which 9 spectral classes of rocks were identified (Fig. 1D). Each class has diagnostic spectral features that reflect a common mineralogic interpretation. More recently, as Curiosity traversed through the clay-rich region, Glen Torridon (GT), there was some variation in the rock spectral classes potentially due to nontronite and other phyllosilicates, but not enough to warrant new spectral classes (Fig. 1B). We hypothesize that new classes will appear in accordance with sulfate-bearing strata and the marker band, specifically appearing as a ‘downturn’ in the last two wavelength filters that is inherent, but not unique, to polyhydrated Mg-sulfates. Here, we expand upon our analysis of Mastcam multispectral observations through Curiosity’s second encounter with the marker band (up to sol 3672), comparing the spectral diversity within the sulfate-bearing unit and the marker band to the spectral classes encountered previously in the traverse. These analyses will provide a basis for comparison and aid in selecting targets for in-situ investigations as Curiosity continues its ascent of Mt. Sharp.

A M Eng↗
NASA NTRS2013

The NASA Meter Class Autonomous Telescope: Ascension Island

The Meter Class Autonomous Telescope (MCAT) is the newest optical sensor dedicated to NASA s mission to characterize the space debris environment. It is the successor to a series of optical telescopes developed and operated by the JSC Orbital Debris Program Office (ODPO) to monitor and assess the debris environment in (1) Low Earth Orbit (LEO), (2) Medium Earth Orbit (MEO), and (3) Geosynchronous Orbit (GEO), with emphasis on LEO and GEO altitudes. A joint NASA-Air Force Research Labs project, MCAT is a 1.3m optical telescope dedicated to debris research. Its optical path and sensor yield a large survey fence at the cutting edge of current detector performance. It has four primary operational observing modes, two of which were not computationally feasible a decade ago. Operations are supported by a sophisticated software suite that monitors clouds and weather conditions, and controls everything from data collection to dome rotation to processing tens of GB of imagery data nightly. With fainter detection limits, precision detection, acquisition and tracking of targets, multi-color photometry, precision astrometry, automated reacquisition capability, and the ability to process all data at the acquisition rate, MCAT is capable of producing and processing a volume and quality of data far in excess of any current (or prior) ODPO operations. This means higher fidelity population inputs and eliminating the multi-year backlog from acquisition-to-product typical of optical campaigns. All of this is possible given a suitable observing location. Originally planned for the island of Legan, part of the Kwajalein Atoll Islands, recent developments have led to a change in venue. Specifically, the Ground-based Electro-Optical Deep Space Surveillance, or GEODSS, System of telescopes is the United States major tracking system for deep space. This network consists of telescopes in Maui, Hawaii; Diego Garcia (Indian Ocean), and Socorro, New Mexico. A fourth optical telescope, though smaller in size, has been operating in conjunction with this effort until recently in M.ron, Spain. With the M.ron site closing, a significant gap in longitude exists between the New Mexico and Diego Garcia sites. This longitudinal gap is well covered by placing a telescope on Ascension Island (7degrees 58'20" S, 14degrees 24'4"W), in the Atlantic Ocean. Ascension Island offers the benefits of both location and weather. The near equatorial location affords the opportunity to access under-sampled low-inclination orbits and new GEO longitudes, while simultaneously filling in the GEODSS longitudinal gap. Ascension Island is a volcanic, desert island, receiving only 7" of rain per year on average. With consistent trade winds blowing from the SSE direction off Africa, the combination of an island location with consistent winds will create the smooth laminar flow sought after by all astronomical sites, which creates stable atmospheric ('seeing') conditions. Finally, this low population island has minimal lighting, resulting in very dark skies, ideal for an observatory.

Lederer, S. M.↗
NASA NTRS2008

Model of Image Artifacts from Dust Particles

A mathematical model of image artifacts produced by dust particles on lenses has been derived. Machine-vision systems often have to work with camera lenses that become dusty during use. Dust particles on the front surface of a lens produce image artifacts that can potentially affect the performance of a machine-vision algorithm. The present model satisfies a need for a means of synthesizing dust image artifacts for testing machine-vision algorithms for robustness (or the lack thereof) in the presence of dust on lenses. A dust particle can absorb light or scatter light out of some pixels, thereby giving rise to a dark dust artifact. It can also scatter light into other pixels, thereby giving rise to a bright dust artifact. For the sake of simplicity, this model deals only with dark dust artifacts. The model effectively represents dark dust artifacts as an attenuation image consisting of an array of diffuse darkened spots centered at image locations corresponding to the locations of dust particles. The dust artifacts are computationally incorporated into a given test image by simply multiplying the brightness value of each pixel by a transmission factor that incorporates the factor of attenuation, by dust particles, of the light incident on that pixel. With respect to computation of the attenuation and transmission factors, the model is based on a first-order geometric (ray)-optics treatment of the shadows cast by dust particles on the image detector. In this model, the light collected by a pixel is deemed to be confined to a pair of cones defined by the location of the pixel s image in object space, the entrance pupil of the lens, and the location of the pixel in the image plane (see Figure 1). For simplicity, it is assumed that the size of a dust particle is somewhat less than the diameter, at the front surface of the lens, of any collection cone containing all or part of that dust particle. Under this assumption, the shape of any individual dust particle artifact is the shape (typically, circular) of the aperture, and the contribution of the particle to the attenuation factor for a given pixel is the fraction of the cross-sectional area of the collection cone occupied by the particle. Assuming that dust particles do not overlap, the net transmission factor for a given pixel is calculated as one minus the sum of attenuation factors contributed by all dust particles affecting that pixel. In a test, the model was used to synthesize attenuation images for random distributions of dust particles on the front surface of a lens at various relative aperture (F-number) settings. As shown in Figure 2, the attenuation images resembled dust artifacts in real test images recorded while the lens was aimed at a white target.

Willson, Reg↗