ALBERT

Description: Author: Jake Yeston

Description: Author: Jake Yeston

Description: Author: Jake Yeston

Description: Author: Jake Yeston

Description: Polynitrogens have the potential for ultrahigh-performing explosives or propellants because singly or doubly bonded polynitrogens can decompose to triply bonded dinitrogen (N2) with an extraordinarily large energy release. The large energy content and relatively low activation energy toward decomposition makes the synthesis of a stable polynitrogen allotrope an extraordinary challenge. Many elements exist in different forms (allotropes)—for example, carbon can exist as graphite, diamond, buckyballs, or graphene. However, no stable neutral allotropes are known for nitrogen, and only two stable homonuclear polynitrogen ions had been isolated until now—namely, the N3− anion (1) and the N5+ cation (2). On page 374 of this issue, Zhang et al. (3) report the synthesis and characterization of the first stable salt of the cyclo-N5− anion, only the third stable homonuclear polynitrogen ion ever isolated. Author: Karl O. Christe

Description: No abstract available

Description: No abstract available

Description: We present a spherical harmonic solution of the static gravity field of Mars to degree and order 120, GMM-3, that has been calculated using the Deep Space Network tracking data of the NASA Mars missions, Mars Global Surveyor (MGS), Mars Odyssey (ODY), and the Mars Reconnaissance Orbiter (MRO). We have also jointly determined spherical harmonic solutions for the static and time-variable gravity field of Mars, and the Mars k 2 Love numbers, exclusive of the gravity contribution of the atmosphere. Consequently, the retrieved time-varying gravity coefficients and the Love number k 2 solely yield seasonal variations in the mass of the polar caps and the solid tides of Mars, respectively. We obtain a Mars Love number k 2 of 0.1697 +/-0.0027 (3- sigma). The inclusion of MRO tracking data results in improved seasonal gravity field coefficients C 30 and, for the first time, C 50 . Refinements of the atmospheric model in our orbit determination program have allowed us to monitor the odd zonal harmonic C 30 for approx.1.5 solar cycles (16 years). This gravity model shows improved correlations with MOLA topography up to 15% larger at higher harmonics ( l = 6080) than previous solutions.

Description: No abstract available

Description: The solar tide in an ancient Venusian ocean is simulated using a dedicated numerical tidal model. Simulations with varying ocean depth and rotational periods ranging from minus 243 to 64 sidereal Earth days are used to calculate the tidal dissipation rates and associated tidal torque. The results show that the tidal dissipation could have varied by more than 5 orders of magnitude, from 0.001 to 780 gigawatts (GW), depending on rotational period and ocean depth. The associated tidal torque is about 2 orders of magnitude below the present day Venusian atmospheric torque, and could change the Venusian daylength by up to 72 days per million years depending on rotation rate. Consequently, an ocean tide on ancient Venus could have had significant effects on the rotational history of the planet. These calculations have implications for the rotational periods of similarly close-in exoplanetary worlds and the location of the inner edge of the liquid water habitable zone.

Description: The north polar cap (NPC) on Mars is the major reservoir of atmospheric water (H2O) currently on Mars. The retrieval and monitoring of atmospheric water vapor abundance are crucial for tracking the cycle of water above the NPC. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter (MRO) has provided a wealth of data that extend over 5 + Martian years, covering the time period between 2006 and 2016. CRISM is ideally suited for spring and summer observations of the north polar region (latitudes poleward of 60 N). The retrievals of water vapor column abundances over this extended period of time were performed over both ice-free and water ice covered surfaces, extending the coverage of the water vapor maps to include the permanent cap, where a maximum value of 90 precipitable micrometers (prm) is retrieved, as compared to 60 prm over ice-free regions in the North Polar Region. Away from summertime maximum, modest interannual variability in the water vapor abundance is observed. Zonal averages over all the observed Martian years combined show a developing water front that shifts northward towards summer, before dissipating over the permanent cap during mid-summer. A prominent feature at latitudes around 75 N shows large abundances of water vapor, indicating a water vapor annulus encircling the retreating edge of the seasonal polar cap during late spring. Meridional transport of water modeled here show that the annulus may be a result of the convergence of water vapor from both south and north along the retreating edge of the NPC.

Description: The habitable zone (HZ) is commonly defined as the range of distances from a host star within which liquid water, a key requirement for life, may exist on a planet's surface. Substantially more CO2 than present in Earth's modern atmosphere is required to maintain clement temperatures for most of the HZ, with several bars required at the outer edge. However, most complex aerobic life on Earth is limited by CO2 concentrations of just fractions of a bar. At the same time, most exoplanets in the traditional HZ reside in proximity to M dwarfs, which are more numerous than Sun-like G dwarfs but are predicted to promote greater abundances of gases that can be toxic in the atmospheres of orbiting planets, such as carbon monoxide (CO). Here we show that the HZ for complex aerobic life is likely limited relative to that for microbial life. We use a 1D radiative-convective climate and photochemical models to circumscribe a Habitable Zone for Complex Life (HZCL) based on known toxicity limits for a range of organisms as a proof of concept. We find that for CO2 tolerances of 0.01, 0.1, and 1 bar, the HZCL is only 21%, 32%, and 50% as wide as the conventional HZ for a Sun-like star, and that CO concentrations may limit some complex life throughout the entire HZ of the coolest M dwarfs. These results cast new light on the likely distribution of complex life in the universe and have important ramifications for the search for exoplanet biosignatures and technosignatures.

Description: Four, quasi-circular, positive Bouguer gravity anomalies (PBGAs) that are similar in diameter (~90-190 km) and gravitational amplitude (〉 140 mGal contrast) are identified within the central Oceanus Procellarum region of the Moon. These spatially associated PBGAs are located south of Aristarchus Plateau, north of Flamsteed crater, and two are within the Marius Hills volcanic complex (north and south). Each is characterized by distinct surface geologic features suggestive of ancient impact craters and/or volcanic/plutonic activity. Here, we combine geologic analyses with forward modeling of high-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) mission in order to constrain the subsurface structures that contribute to these four PBGAs. The GRAIL data presented here, at spherical harmonic degrees 6660, permit higher resolution analyses of these anomalies than previously reported, and reveal new information about subsurface structures. Specifically, we find that the amplitudes of the four PBGAs cannot be explained solely by mare-flooded craters, as suggested in previous work; an additional density contrast is required to explain the high-amplitude of the PBGAs. For Northern Flamsteed (190 km diameter), the additional density contrast may be provided by impact-related mantle uplift. If the local crust has a density ~2800 kg/cu.m, then ~7 km of uplift is required for this anomaly, although less uplift is required if the local crust has a lower mean density of ~2500 kg/cu.m. For the Northern and Southern Marius Hills anomalies, the additional density contrast is consistent with the presence of a crustal complex of vertical dikes that occupies up to ~50% of the regionally thin crust. The structure of Southern Aristarchus Plateau (90 km diameter), an anomaly with crater-related topographic structures, remains ambiguous. Based on the relatively small size of the anomaly, we do not favor mantle uplift; however, understanding mantle response in a region of especially thin crust needs to be better resolved. It is more likely that this anomaly is due to subsurface magmatic material given the abundance of volcanic material in the surrounding region. Overall, the four PBGAs analyzed here are important in understanding the impact and volcanic/plutonic history of the Moon, specifically in a region of thin crust and elevated temperatures characteristic of the Procellarum KREEP Terrane.

Description: While devoid of an active magnetic dynamo field today, Mars possesses a remanent magnetic field that may reach several thousand nanoteslas locally. The exact origin and the events that have shaped the crustal magnetization remain largely enigmatic. Three magnetic field data sets from two spacecraft collected over 13 cumulative years have sampled the Martian magnetic field over a range of altitudes from 90 up to 6,000 km: (a) Mars Global Surveyor (MGS) magnetometer (19972006), (b) MGS Electron Reflectometer (19992006), and (c) Mars Atmosphere and Volatile EvolutioN (MAVEN) magnetometer (2014 to today). In this paper we combine these complementary data sets for the first time to build a new model of the Martian internal magnetic field. This new model improves upon previous ones in several aspects: comprehensive data coverage, refined data selection scheme, modified modeling scheme, discrete-to-continuous transformation of the model, and increased model resolution. The new model has a spatial resolution of 160 km at the surface, corresponding to spherical harmonic degree 134. It shows small scales and well-defined features, which can now be associated with geological signatures.

Description: Amorphous solid water (ASW) is found on icy dust grains in the interstellar medium (ISM), as well as on comets and other icy objects in the outer solar system. The optical properties of ASW are thus relevant for many astrophysical environments, but in the ultravioletvisible (UVvis), its refractive index is not well constrained. Here, we introduce a new method based on UVvis broadband interferometry to measure the wavelength dependent refractive index n() of amorphous water ice from 10 to 130 K, i.e., for different porosities, in the wavelength range of 210757 nm. We also present n() for crystalline water ice at 150 K, which allows us to compare our new method with literature data. Based on this, a method to calculate n(, ) as a function of wavelength and porosity is reported. This new approach carries much potential and is generally applicable to pure and mixed ice, both amorphous and crystalline. The astronomical and physicalchemical relevance and future potential of this work are discussed.

Description: The Compact Reconnaissance Imaging Spectral Mapper (CRISM) onboard the Mars Reconnaissance Orbiter (MRO) obtains pole-to-pole observations (i.e., full MRO orbits) of vertical profiles for visible/near-IR spectra (=0.44.0 m), which are ideally suited to identifying the composition and particle sizes of Mars ice and dust aerosols over 50100 km altitudes in the Mars mesosphere. Within the coverage limitations of the CRISM limb data set, a distinct compositional dichotomy is found in Mars mesospheric ice aerosols. CO2 ice clouds appear during the aphelion period of Mars orbit (Solar Longitudes, Ls0160) at low latitudes (20S10N) over specific longitude regions (Meridiani, Valles Marineris) and at typical altitudes of 5575 km. Apart from faint water ice hazes below 55 km, mesospheric H2O ice clouds are primarily restricted to the perihelion orbital range (Ls160 350) at northern and southern mid-to-low latitudes with less apparent longitudinal dependences. Mars mesospheric CO2 clouds are presented in CRISM spectra with a surprisingly large range of particle sizes (cross section weighted radii, Reff=0.3 to 2.2 m). The smaller particle sizes (Reff 1 m) appear concentrated near the spatial (latitude and altitude) boundaries of their global occurrences. CRISM spectra of mesospheric CO2 clouds also show evidence of iridescence, indicating very narrow particle size distributions (effective variance, Veff0.03) and so very abrupt CO2 cloud nucleation. Furthermore, these clouds are sometimes accompanied by altitude coincident peaks in 1.27 m O2 dayglow, which indicates very dry, cold regions of formation. Mesospheric water ice clouds generally exhibit small particle sizes (Reff=0.10.3 m), although larger particle sizes (Reff=0.40.7 m) appear infrequently. On average, water ice cloud particle sizes decrease with altitude over 5080 km in the perihelion mesosphere. Water ice mass appears similar in clouds over a large range of observed cloud particle sizes, with particle number densities increasing to 10 cm3 for Reff=0.2 m. Near coincident Mars Climate Sounder (MCS) temperature and aerosol profile measurements for a subset of CRISM mesospheric aerosol measurements indicate near saturation (H2O and CO2) conditions for ice clouds and distinct mesospheric temperature increases associated with mesospheric dust loading. Dayside (3 pm) mesospheric CO2 clouds with larger particle sizes (Reff 0.5 m) scatter surface infrared emission in MCS limb infrared radiances, as well as solar irradiance in the MCS solar band channel. Scattering of surface infrared emission is most strikingly presented in nighttime (3 am) MCS observations at 5560 km altitudes, indicating extensive mesospheric nighttime CO2 clouds with considerably larger particle sizes (Reff7 m). Mesospheric CO2 ice clouds present cirrus-like waveforms over extensive latitude and longitude regions (1010), as revealed in coincident Mars Color Imager (MARCI) nadir imaging. Solar tides, gravity waves, and the large orbital variation of the extended thermal structure of the Mars atmosphere influence all of these behaviors. Mesospheric dust aerosols appear infrequently over the non-global (planet encircling) dust storm era of the CRISM limb data set (20092016), and exhibit smaller particle sizes (Reff=0.20.7 m) relative to dust in the lower atmosphere. One isolated case of an aphelion (Ls=96) mesospheric dust layer with large dust particle sizes (Reff 2 m) over Syria Planum may reflect high altitude, non-local transport of dust over elevated regions.

Description: The surface of Mars exhibits strong evidence for a widespread and long-lived cryosphere. Observations of the surface have identified phases produced by water-rock interactions, but the contribution of glaciers to the observed alteration mineralogy is unclear. To characterize the chemical alteration expected on an icy early Mars, we collected water and rock samples from terrestrial glaciated volcanics. We related geochemical measurements of meltwater to the mineralogy and chemistry of proglacial rock coatings. In these terrains, water is dominated by dissolved silica relative to other dissolved cations, particularly at mafic sites. Rock coatings associated with glacial striations on mafic boulders include a silica-rich component, indicating that silica precipitation is occurring in the subglacial environment. We propose that glacial alteration of volcanic bedrock is dominated by a combination of high rates of silica dissolution and precipitation of opaline silica. On Mars, cryosphere-driven chemical weathering could be the origin of observed silica-enriched phases.

Description: Photometry from the Helios and STEREO spacecraft revealed regions of enhanced sky surface-brightness suggesting a narrow circumsolar ring of dust associated with Venus's orbit. We model this phenomenon by integrating the orbits of 10,000,000+ dust particles subject to gravitational and non-gravitational forces, considering several different kinds of plausible dust sources. We find that only particles from a hypothetical population of Venus co-orbital asteroids can produce enough signal in a narrow ring to match the observations. Previous works had suggested such objects would be dynamically unstable. However, we re-examined the stability of asteroids in 1:1 resonance with Venus and found that ~8% should survive for the age of the solar system, enough to supply the observed ring.

Description: Infrared excesses due to dusty disks have been observed orbiting white dwarfs with effective temperatures between 7200 and 25,000 K, suggesting that the rate of tidal disruption of minor bodies massive enough to create a coherent disk declines sharply beyond 1 Gyr after white dwarf formation. We report the discovery that the candidate white dwarf LSPM J0207+3331, via the Backyard Worlds: Planet 9 citizen science project and Keck Observatory follow-up spectroscopy, is hydrogen dominated with a luminous compact disk (L IR/L star = 14%) and an effective temperature nearly 1000 K cooler than any known white dwarf with an infrared excess. The discovery of this object places the latest time for large-scale tidal disruption events to occur at ~3 Gyr past the formation of the host white dwarf, making new demands of dynamical models for planetesimal perturbation and disruption around post-main-sequence planetary systems. Curiously, the mid-infrared photometry of the disk cannot be fully explained by a geometrically thin, optically thick dust disk as seen for other dusty white dwarfs, but requires a second ring of dust near the white dwarf's Roche radius. In the process of confirming this discovery, we found that careful measurements of WISE source positions can reveal when infrared excesses for white dwarfs are co-moving with their hosts, helping distinguish them from confusion noise.

Description: Mercury is surrounded by a tenuous exosphere in which particles travel on ballistic trajectories under the influence of a combination of gravity and solar radiation pressure. The densities are so small that the surface forms the exobase and particles in the exosphere are more likely to collide with it rather than with each other. For a planet with a more substantial collision-dominated atmosphere, a population of particles that enters from below the exobase supplies the exosphere. In contrast Mercury's exosphere is supplied both by incoming sources including the solar wind (hydrogen and helium), micrometeoroids (dust), meteoroids and cornets, and by particles released from the surface through a variety of processes that include sputtering by solar wind ions, desorption by solar photons and electrons, impacts by micrometeoroids, and thermal desorption of surface materials. These source processes are balanced by loss processes, which include impact with and sticking to the surface, Jeans (or thermal) escape, ionization followed by transport along magnetic field lines, and acceleration by solar radiation pressure to escape velocity. Ground-based attempts to detect an atmosphere around Mercury before Mariner 10 first visited the planet in 1974 were unsuccessful and led only to increasingly tight upper limits, culminating in a limiting value for surface atmospheric pressure of 0.015 Pascal (Pa) determined by Fink et al. (1974).

Description: The Mars Reconnaissance Orbiter (MRO) entered Mars orbit on March 10, 2006. After five months of aerobraking, a series of propulsive maneuvers were used to establish the desired low-altitude science orbit. The spacecraft has been on station in its 255 x 320 km, sun-synchronous (~3 am-pm), primary science orbit since September 2006 performing both scientific and Mars programmatic support functions. This paper will provide a summary of the major achievements of the mission to date and the major flight activities planned for the remainder of its third Extended Mission (EM3). Some of the major flight challenges the flight team has faced are also discussed.

Description: No abstract available

Description: Found on all terrestrial planets, wrinkle ridges are anticlines formed by thrust faulting and folding resulting from crustal shortening. The MErcury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft's orbital phase returned high resolution images and topographic data of the previously unimaged northern high latitudes of Mercury where there are large expanses of smooth plains deformed by wrinkle ridges. Concurrently, the Lunar Reconnaissance Orbiter (LRO) is obtaining high resolution images and topographic data covering lunar mare wrinkle ridges. These data allow quantitative comparison of the scale of wrinkle ridges in smooth plains volcanic units on Mercury with mare wrinkle ridges. We evaluate the topographic relief of 300 wrinkle ridges within and outside of mascon basins on the Moon and Mercury. Measured wrinkle ridges range from ~112 to 776 m in relief with a mean of ~350 m (median = ~340 m, n = 150) on Mercury and from ~47 to 678 m in relief with a mean of ~198 m (median = ~168 m, n = 150) on the Moon. Wrinkle ridges on Mercury thus are approximately twice as large in mean relief compared to their counterparts on the Moon. The larger scale of Mercury's wrinkle ridges suggests that their formation can be attributed, in part, to global contraction. As global contraction on the Moon is estimated to be an order of magnitude smaller than on Mercury, the smaller scale of lunar wrinkle ridges suggests they most likely form primarily by load induced subsidence of the mare basalt. Wrinkle ridges located in lunar mascon basins and in the Caloris mascon on Mercury are not statistically significantly different in relief than ridges in non-mascon regions, suggesting comparable levels of contractional strain. The fact that mascon basins do not host wrinkle ridges with greater structural relief relative to non-mascon units may indicate the critical role lithospheric thickness plays in controlling subsidence and contraction of thick volcanic sequences on the Moon and Mercury.

Description: A high-fidelity approach for simulating the aerothermodynamic environments of meteor entries was developed, which allows the commonly assumed heat transfer coefficient of 0.1 to be assessed. This model uses chemically reacting computational fluid dynamics (CFD), coupled with radiation transport and surface ablation. Coupled radiation accounts for the impact of radiation on the flowfield energy equations, while coupled ablation explicitly models the injection of ablation products within the flowfield and radiation simulations. For a meteoroid with a velocity of 20 km/s, coupled radiation is shown to reduce the stagnation point radiative heating by over 60%. The impact of coupled ablation (with coupled radiation) is shown to provide at least a 70% reduction in the radiative heating relative to cases with only coupled radiation. This large reduction is partially the result of the low ionization energies of meteoric ablation products relative to air species. The low ionization energies of ablation products, such as Mg and Ca, provide strong photoionization and atomic line absorption in regions of the spectrum that air species do not. MgO and CaO are also shown to provide significant absorption. Turbulence is shown to impact the distribution of ablation products through the shock-layer, which results in up to a 100% increase in the radiative heating downstream of the stagnation point. To create a database of heat transfer coefficients, the developed model was applied to a range of cases. This database considered velocities ranging from 14 to 20 km/s, altitudes ranging from 20 to 50 km, and nose radii ranging from 1 to 100 m. The heat transfer coefficients from these simulations are below 0.045 for the range of cases, for both laminar and turbulent, which is significantly lower than the canonical value of 0:1. When the new heat transfer model is applied to a Tunguska-like 15 Mt entry, the effect of the new model is to lower the height of burst by up to 2 km, depending on assumed entry angle. This, in turn, results in a significantly larger ground damage footprint than when the canonical heating assumption is used.

Description: This document describes the trajectory and atmosphere reconstruction of the Mars Phoenix Entry, Descent, and Landing using the New Statistical Trajectory Estimation Program. The approach utilizes a Kalman filter to blend inertial measurement unit data with initial conditions and radar altimetry to obtain the inertial trajectory of the entry vehicle. The nominal aerodynamic database is then used in combination with the sensed accelerations to obtain estimates of the atmosphere-relative state. The reconstructed atmosphere pro le is then blended with pre-flight models to construct an estimate of the as-flown atmosphere.

Description: This paper develops an atmospheric state estimator based on inertial acceleration and angular rate measurements combined with a vehicle aerodynamic model. The approach uses the navigation state of the vehicle to recast the vehicle aerodynamic model to be a function solely of the atmospheric state. Force and moment measurements are based on vehicle sensed accelerations and angular rates. These measurements are combined with an aerodynamic model and a KalmanSchmidt filter to estimate the atmospheric conditions. The method is applied to data from the Mars Science Laboratory mission, which landed the Curiosity rover on the surface of Mars in August 2012. The results of the estimation algorithm are compared with results from a flush air data sensing algorithm based on onboard pressure measurements on the vehicle forebody. The comparison indicates that the proposed method provides estimates consistent with the air data measurements, without the use of pressure transducers. Implications for future missions such as the Mars 2020 entry capsule are described.

Description: The observations of Mercury's exosphere described in Chapter 14 have led to many modeling efforts. Early models were based upon a few simple assumptions and primarily explored the dynamics of sodium atoms pushed anti-sunward by radiation pressure [Ip, 1986; Smyth and Marconi, 1995]. More recently, these early models have been superseded by simulations with an increasing number of interdependent source processes [Leblanc and Johnson, 2003; Mura et al., 2009; Leblanc and Johnson, 2010; Burger et al., 2010, 2012, 2014]. We briefly summarize the source and loss processes before describing the published exosphere models, first for the three species observed almost continuously during the MESSENGER mission by the Ultraviolet and Visible Spectrometer (UVVS) channel of the Mercury Atmospheric and Surface Composition2Spectrometer (MASCS), (Na, Mg and Ca), and then more briefly for other species that have been observed or for which new upper limits have been derived.15.1 Overview of Source and Loss Processes15.1.1 Source Processes15.1.1.1 Thermal DesorptionThermal desorption (or thermal evaporation) is the release of adsorbed atoms from a surface via heating. Thermal desorption is related to the binding energy of the atom on the surface and the vibrational frequency of the bound atom, such that the rate of thermal desorption is given by, (15.1)where TD,

Description: We scoured the full set of blue-wavelength Hubble Space Telescope images of Neptune, finding one additional dark spot in new Hubble data beyond those discovered in 1989, 1994, 1996, and 2015. We report the complete disappearance of the SDS-2015 dark spot, using new Hubble data taken on 2018 September 910, as part of the Outer Planet Atmospheres Legacy (OPAL) program. Overall, dark spots in the full Hubble data set have lifetimes of at least one to two years, and no more than six years. We modeled a set of dark spots randomly distributed in time over the latitude range on Neptune that is visible from Earth, finding that the cadence of archival Hubble images would have detected about 70% of these spots if their lifetimes are only one year, or about 85%95% of simulated spots with lifetimes of two or more years. Based on the Hubble data set, we conclude that dark spots have average occurrence rates of one dark spot every four to six years. Many numerical models to date have simulated much shorter vortex lifetimes, so our findings provide constraints that may lead to improved understanding of Neptunes wind field, stratification, and humidity.

Description: This document is derived from the former National Aeronautics and Space Administration (NASA) Constellation Program (CxP) document CxP 70023, titled The Design Specification for Natural Environments (DSNE), Revision C. The original document has been modified to represent updated Design Reference Missions (DRMs) for the NASA Exploration Systems Development (ESD) Programs.

Description: The Submillimeter Enceladus Life Fundamentals Instrument (SELFI) is a passive remote sensing submillimeter heterodyne spectrometer being developed at NASA GSFC under NASA's Maturation of Instruments for Solar System Exploration (MatISSE) program. SELFI will advance submillimeter receiver technology by 1) investigating the chemical and isotopic compositions and corresponding densities of Enceladus' plume material, their vertical thermal structures, and the transport mechanisms within the plumes, and 2) characterizing the source regions from which the plumes emerge. The Enceladus plumes are important in the context of life and habitability of its subsurface ocean environment. SELFI remote sensing measurements will 1) measure the spatial and temporal variabilities in the plume chemical compositions, 2) provide insight in to Enceladus' subsurface ocean environment by monitoring H2O, HDO, d18O, and d17O, 3) constrain the oxidation state of the subsurface ocean using H2O2 and O3, and 4) utilize the SO2 and H2S spectral signatures to constrain the impact arising from both the sea-floor volcanoes and pre-biotic molecules. Moreover, the detection of the remaining molecular species (14 in total) is vital to improving the current state of knowledge of Enceladus' subsurface ocean habitability this also permits us to explore the chemical alteration processes arising from primordial volatiles that have been observed in comets. Lastly, SELFI's continuum observations enable the correlation between observed variations in plume activity with surface temperatures.SELFI is currently being developed under a technology maturation program that will advance the RF-to-digital electronics of a submillimeter-wave heterodyne spectrometer to simultaneously observe fourteen molecular species with resonances between 530 GHz and 600 GHz. SELFI will have fine radiometric resolution, high spectral resolution (resolving power R 〉 106), multiple continuum channels and a high dynamical range, necessary to map Enceladus across its 30 K to 250 K temperature range. Under the MatISSE program, SELFI will advance from TRL 4 to 6 four key technologies of the RF-to-digital subsystem, which are: 1) the RF low noise amplifier design; 2) the single-sideband (SSB) mixer and local oscillator; 3) the IF assembly down-converter that maps the fourteen species to 2 x 500 MHz bandwidth; and 4) the digital spectrometer electronics.

Description: Upon its approach to orbit the dwarf planet Ceres in early 2015, optical navigation and dedicated satellite search images were acquired with the Dawn mission's framing camera 2. A team of searchers individually processed and examined the images for evidence of objects moving with Ceres. Completeness of search with respect to the space searched was calculated as a function of distance to Ceres and found to be complete down to 15 Ceres radii (Ceres' mean radius is 470 kilometers). Upper limits of detectable magnitude were determined for each observed set of images and an upper limit in size was calculated assuming for the putative objects, Ceres' geometric albedo of 0.11. Nothing was found associated with Ceres down to a radius of 12 meters for the most sensitive search, and down to a radius of 323m for the least sensitive search circumstances. Examination of the physical properties of the 41 largest and most massive main belt asteroids suggests that large asteroids without satellites are intact and their interiors have internal strength. This is consistent with results from the Dawn mission at both Vesta and Ceres. Ceres' volatile-rich composition also is a likely contributor to both the absence of satellites at Ceres and of Ceres meteorites at Earth. These results suggest that collisional disruption creating rubble pile structure is a necessary condition for formation of satellites around main belt asteroids.

Description: Mars is a dusty planet. Wind often lifts dust from the surface into the air forming clouds of dust at different locations across Mars. These dust storms typically last up to a couple days and grow to a few hundred km in size. However, once in a long while when conditions are just right, localized dust storms can interact in a way that optically thick suspended dust covers nearly the entire planet remaining aloft for weeks to months. These global-scale dust storms are the most dramatic of all weather phenomena on Mars, greatly altering the thermal structure and dynamics of the Martian atmosphere and significantly changing the global distribution of surface dust. Such a global-scale dust storm occurred during the summer of 2018, the first such event since 2007. The global dust storm was observed by an international fleet of spacecraft in Mars orbit and on the surface of Mars providing an unprecedented view of the initiation, growth, and decay of the storm as well as the physical properties of the dust during the storm's evolution. The 2018 global-scale dust storm was observed to grow from several localized dust-lifting centers with wind-blown dust suspended in the atmosphere encircling Mars after about two weeks of activity. Dust column optical depths recorded by the Opportunity and Curiosity rovers on the surface were the highest ever recorded on Mars. Peak global intensity of the dust storm was reached in early July 2018. Over the next couple months, the dust settled out and the atmosphere returned to its climatological average. Only a small number of global-scale dust storms have been observed on Mars, and so detailed analysis of the observations of this storm will provide important new insight into how these events occur and their effect on the current Mars climate.

Description: The crystallographic orientations of chondrule minerals can provide important insights into their formation and deformational history. For example, the orientations of the olivine bars and surrounding rim in barred olivine chondrules provide information and on the conditions of crystallization and the orientations and shapes of olivines within porphritic chondrules can record the reactions with the surrounding nebular gas during chondrule formation. Later deformation on the parent body can cause crystal-plastic deformation of chondrule minerals that is evident through their intracrystalline lattice misorientations. Typically these crystal orientations and lattice misorientations are determined using electron backscatter diffraction (EBSD) on thin sections but this gives only a 2D picture for what is actually a 3D texture. While it is possible to combine EBSD with serial sectioning to build a 3D dataset of texture, this is a destructive, time-intensive process. A recent technological development that enables non-destructive, 3D crystallographic orientation measurement is X-ray diffraction contrast tomography (DCT), which uses the X-ray diffraction of the crystal lattice to determine orientation. Originally only possible using monochromatic X-ray beams at 3rd generation synchrotron light sources, DCT has been recently adapted to polychromatic sources of laboratory X-ray microscopes (referred to as Lab-DCT). Up to this point LabDCT has only been applied to large, well-formed crystals of high symmetry (i.e., metals), but we recently acquired DCT datasets for a pair Bjurble chondrules to determine the applicability of the technique to natural, mutlimineralic samples composed predominately of olivine (i.e., chondrules).

Description: The Lunar Reconnaissance Orbiter (LRO) launched in 2009 to collect the dataset required for future surface missions and to answer key questions about the lunar surface environment. In the first seven years of operations, the Lunar Reconnaissance Orbiter Camera (LROC) acquired over a million images of the lunar surface and collected key stereo observations for the production of meter-scale digital terrain models. Due to the configuration of the LRO orbit, LROC and the other onboard instruments have the opportunity to acquire observations at or near the poles every two hours. The lunar south polar region is an area of interest for future surface missions due to the benign thermal environment and areas of near-continuous illumination. These persistently illuminated regions are also adjacent to permanently shadowed areas (e.g. floors of craters and local depressions) that are of interest to both scientists and engineers prospecting for cold-trapped volatiles on or near the surface for future in situ resource utilization. Using a terramechanics model based on surface properties derived during the Apollo and Luna missions, we evaluated the accessibility of different science targets and the optimal traverse paths for a given set of waypoints. Assuming a rover that relies primarily on solar power, we identified a traverse that would keep the rover illuminated for 94.43% of the year between 1 January 2021 and 31 December 2021. Throughout this year-long period, the longest eclipse endured by the rover would last only 101 hours and the rover would move a total of 22.11 km with an average speed of 2.5 m/hr (max speed=30 m/hr). During this time the rover would be able to explore a variety of targets along the connecting ridge between Shackleton and de Gerlache craters. In addition to the southern polar regions, we are also examining traverses around other key exploration sites such as Marius Hills, Ina-D, Rima Parry, and the Mairan Domes in efforts to aid future mission planners and assess the requirements for future roving prospectors (e.g., maximum speed, maximum slope, etc.).

Description: The Utah Test and Training Range (UTTR), southwest of Salt Lake City, Utah, is the site of all NASA unmanned sample return missions. To date these missions include the Genesis solar wind samples (2004) and Stardust cometary and interstellar dust samples (2006). NASAs OSIRIS-REx Mission will return its first asteroid sample at UTTR in 2023.

Description: Since early 2015, the Mars Exploration Rover Opportunity has been exploring the break in the rim of Endeavour Crater dubbed Marathon Valley by the rover team. Marathon Valley was identified by orbital hyperspectral data from the MRO CRISM as having a relatively strong spectral feature in the 2.3 micrometer region indicative of an Mg or Fe-OH combination overtone absorption band indicative of smectite clay. Earlier in its mission, Opportunity examined the Matijevic Hill region on the more northerly Cape York crater rim segment and found evidence for smectite clays in a stratigraphically lower, pre-impact formed unit dubbed the Matijevic formation. However, the smectite exposures in Marathon Valley appear to be associated with the stratigraphically higher Shoemaker formation impact breccia. Evidence for alteration in this unit in Marathon Valley is provided by Pancam multispectral observations in the 430 to 1010 nm visible/near infrared (VNIR) spectral range. Sinuous troughs ("red zones") contain fragmented cobbles and pebbles displaying higher blue-to-red slopes, moderately higher 535 nm band depths, elevated 754 to 934 nm, and negative 934 to 1009 nm slopes. The lack of an absorption at 864 to 904 nm indicates the lack of crystalline red hematite in these red zones, but likely an enrichment in nanophase ferric oxides. The negative 934 to 1009 nm slope is potentially indicative of the presence of adsorbed or structurally bound water. A scuff in a red zone near the southern wall of Marathon Valley uncovered light-toned soils and a pebble with an 803 to 864 nm absorption resembling that of light-toned Fe-sulfate bearing soils uncovered by the Spirit rover in the Columbia Hills of Gusev crater. APXS chemical measurements indicated enrichments of Mg and S in the scuff soils and the pebble, Joseph Field, with the strongest 803 nm band- consistent with Mg and Fe sulfates. The presence of Fe and Mg sulfates can be interpreted as evidence of a potentially later episode of aqueous alteration with an earlier, neutral to alkaline pH episode forming the Fe/Mg smectites and a later acid pH episode forming the Fe and Mg sulfates.

Description: Mars Exploration Rover Opportunity is exploring the rim of 22 km diameter, Noachian-aged Endeavour crater. Marathon Valley cuts through the central region of the western rim providing a window into the local lower rim stratigraphic record. Spectra from the Compact Reconnaissance Imaging Spectrometer for Mars show evidence for the occurrence of Fe-Mg smectite in this valley, indicating areally extensive and distinct lithologic units and/or styles of aqueous alteration. The Alpha Particle X-ray Spectrometer has determined the compositions of 59 outcrop targets on untreated, brushed and abraded surfaces. Rocks in the Marathon Valley region are soft breccias composed of mm- to cm-sized darker clasts set in a lighter-toned, finegrained matrix. They are basaltic in non-volatile-element composition and compositionally similar to breccias investigated elsewhere on the rim. Alteration styles recorded in the rocks include: (1) Enrichments in Si, Al, Ti and Cr in more reddish-colored rock, consistent with leaching of more soluble cations and/or precipitation of Si +/- Al, Ti, Cr from fluids. Coprecipitation of Ge-rich phases with Si occurred in the western area only; high water:rock is indicated. Pancam multispectral observations indicate higher nanophase ferric oxide contents, but the rocks have lower Fe contents. The highly localized nature of the red zones indicate they cannot be the source of the widespread smectite signature observed from orbit. (2) Outcrops separated by approximately 65 m show common compositional changes between brushed and abraded (approximately 1 mm deep) targets: increases in S and Mg; decreases in Al, Cl and Ca. These changes are likely due to relatively recent, surface-related alteration of valley rocks and formation of surface coatings under low water:rock. (3) One target, from the center of a region of strong CRISM smectite signature, shows modest differences in composition (higher Si, K; lower Mn) compared to most Marathon Valley rocks, while another target approximately 40 cm away on the same outcrop does not; a change towards smectite bulk compositions is not observed. The smectite signature likely resulted from alteration under low water:rock such that primary minerals were partially altered to phyllosilicates, but wholesale leaching of cations by fluids did not occur.

Description: The petrographic study of Itokawa particle, RA-QD02-0127 has been performed by SEM-EDS and optical microscope observations. The purpose of this study is to understand better the metamorphic and impact shock history of asteroid Itokawa, and other S-class asteroids.

Description: This year marks the 40th year anniversary for the Antarctic Search for Meteorite (ANSMET) program. In 1976, the ANSMET program led the first expedition to Antarctica. The ANSMET program is a US-led field-based science project that recovers meteorite samples from Antarctica. Once a year from late November to late January, a field team consisting of 8 to 12 people, spends 6-8 weeks camping on the ice and collecting meteorites. Since 1976, more than 22,000 meteorite samples have been recovered. These meteorites come from asteroids, planets and other bodies of the solar system. Once collected, the Antarctic meteorites are shipped to NASA/Johnson Space Center (JSC) Houston, TX. in a refrigerated truck and are kept frozen to minimize oxidation until they are ready for initial processing. In Antarctica each meteorite is given a field tag which consists of numbers, once in the lab, this is replaced by an official tag, consisting of the Antarctic field location and year collected. The types and numbers of meteorites that have been classified include 849 carbonaceous chondrites, 135 enstatites, 512 achondrites, 64 stony, 115 irons, 48 others (27 R chondrites, 7 ungrouped), 6,161 H chondrites, 7,668 L chondrites, and 4,589 LL chondrites. Although 80-85 percent of the collected meteorites fall in the ordinary chondrite group, the other approximately 15 percent represent rare types of achondrites and carbonaceous chondrites. These rare meteorites include 25 lunar meteorites, 15 Martian meteorites, scores of various types of carbonaceous chondrites, and unique achondrites. The Antarctic meteorites that have been collected are processed in the Meteorite Processing Lab at JSC in Houston, TX. Initial processing of the meteorites begins with thawing/drying the meteorites in a nitrogen glove box for 24 to 48 hours. The meteorites are then photographed, measured, weighed and a description of the interior and exterior of each meteorite is written. The meteorite is broken and a representative sample, either a 1-3 gram chip or thin section is sent to the Smithsonian Institution for classification. After Antarctic meteorites have been classified and approved by the Nomenclature Committee of the Meteoritical Society, they are announced in the Antarctic Meteorite Newsletter, which is published twice per year (fall and spring) so that scientists may review which meteorites are available to study. Requests for Antarctic Meteorite samples are welcomed from research scientists, regardless of their current state of funding for meteorite studies. Since its inception over 3,300 requests have been made for pieces of these meteorites and over 400 investigators worldwide are active in the study of meteorites.. Research on these samples has been published in more than1500 peer reviewed articles; a listing of papers for any meteorite sample can be generated by accessing http://curator.jsc.nasa.gov/antmet/referencesearch.cfm. Antarctic meteorite samples requested by scientists are prepared several different ways. Most samples are prepared as chips, either using a rock splitter or using a chisel and chipping bowl. In special situations, a researcher may request a meteorite slab in which case the samples are cut using a diamond-bladed bandsaw inside of a dry nitrogen glove box. The meteorites are always cut in a 100 percent liquid-free environment. Additionally, thin/thick sections of Antarctic meteorites are also prepared at JSC. The meteorite thin section lab at JSC can prepare standard 30-micron thin sections, thick sections of variable thickness (100 to 200 microns), or demountable sections using superglue, all section are prepared without using water. Although many of the techniques used back in the '70's are still used today, advances in computers, software, databases, available tools and instrumentation have helped to streamline and shorten the duration of the classification process. In conjunction with present day missions to asteroids and other planets, meteorite studies have not only led to a better understanding of the complex histories of these bodies but have also tied certain meteorite groups to particular asteroid bodies. New meteorite discoveries by the ANSMET program provide a cost effective method for obtaining samples of previously unsampled bodies, allowing scientists to learn more about the origin, composition, and evolution of the solar system. Preservation in our cleanrooms at NASA allows material to be archived for future generations and advances in instrumentation and analysis.

Description: The Mars Science Laboratory rover, Curiosity, landed at Gale crater in August 2012 and has been investigating a sequence of dominantly fluviolacustrine sediments deposited 3.6-3.2 billion years ago. Curiosity collects quantitative mineralogical data with the CheMin XRD/XRF instrument and quantitative chemical data with the APXS and ChemCam instruments. These datasets show stratigraphic mineralogical and geochemical variability that suggest a complex aqueous history. The Murray Formation, primarily composed of fine-laminated mudstone, has been studied in detail since the arrival at the Pahrump Hills in September 2014. CheMin data from four samples show variable amounts of iron oxides, phyllosilicates, sulfates, amorphous and crystalline silica, and mafic silicate minerals. Geochemical data throughout the section show that there is significant variability in Zn, Ni, and Mn concentrations. Mineralogical and geochemical trends with stratigraphy suggest one of possibly several aqueous episodes involved alteration in an open system under acidic pH, though other working hypotheses may explain these and other trends. Data from the Murray Formation contrast with those collected from the Sheepbed mudstone located approximately 60 meters below the base of the Murray Formation, which showed evidence for diagenesis in a closed system at circumneutral pH. Ca-sulfates filled late-stage veins in both mudstones.

Description: A variety of recent observations have indicated several possible reservoirs of water and other volatiles. These volatiles, and in particular water, have the potential to be a valuable or enabling resource for future exploration. NASA's Human Exploration and Operations Mission Directorate (HEOMD) Advanced Exploration Systems (AES) is supporting the development of Resource Prospector (RP) to explore the distribution and concentration of lunar volatiles prospecting and to demonstrate In-Situ Resource Utilization (ISRU). The mission includes a NASA developed rover and payload, and a lander will most likely be a contributed element by an international partner or the Lunar Cargo Transportation and Landing by Soft Touchdown (CATALYST) initiative. The RP payload is designed to: (1) locate near-subsurface volatiles, (2) excavate and analyze samples of the volatile-bearing regolith, and (3) demonstrate the form. extractability and usefulness of the materials. RP is being designed with thought given to its extensibility to resource prospecting and ISRU on other airless bodies and Mars. This presentation will describe the Resource Prospector mission, the payload and measurements, and concept of operations

Description: Kepler has vastly increased our knowledge of planets and planetary systems located close to stars. The new data shows surprising results for planetary abundances, planetary spacings and the distribution of planets on a mass-radius diagram. The implications of these results for theories of planet formation will be discussed.

Description: The July encounter with Pluto by the New Horizons spacecraft permitted imaging of its cratered terrains with scales as high as approximately 100 m/pixel, and in stereo. In the initial download of images, acquired at 2.2 km/pixel, widely distributed impact craters up to 260 km diameter are seen in the near-encounter hemisphere. Many of the craters appear to be significantly degraded or infilled. Some craters appear partially destroyed, perhaps by erosion such as associated with the retreat of scarps. Bright ice-rich deposits highlight some crater rims and/or floors. While the cratered terrains identified in the initial downloaded images are generally seen on high-to-intermediate albedo surfaces, the dark equatorial terrain informally known as Cthulhu Regio is also densely cratered. We will explore the range of possible processes that might have operated (or still be operating) to modify the landscape from that of an ancient pristinely cratered state to the present terrains revealed in New Horizons images. The sequence, intensity, and type of processes that have modified ancient landscapes are, among other things, the record of climate and volatile evolution throughout much of the Pluto's existence. The deciphering of this record will be discussed. This work was supported by NASA's New Horizons project.

Description: I will describe water we have found in 4.5 billion year old extraterrestrial salt, and the organics that are also present. We hypothesize that organics being carried through the parent body of the halite have been deposited adjacent to the fluid inclusions, where they have been preserved against any thermal metamorphism. We are making bulk compositional, carbon and hydrogen isotopic measurements of solid organic phases associated with the aqueous fluid inclusions in the meteorites. We will compare these organics with those found in chondrites and Wild-2 comet coma particles to determine whether these classes of organics had an origin within aqueous solutions.

Description: The National Aeronautics and Space Administration (NASA) is developing a robotic mission to visit a large near-Earth asteroid (NEA), collect a multi-ton boulder from its surface, and redirect it into a stable orbit around the Moon. Once returned to cislunar space in the mid-2020s, astronauts will explore the boulder and return to Earth with samples. This Asteroid Redirect Mission (ARM) is part of NASA's plan to advance the technologies, capabilities, and spaceflight experience needed for a human mission to the Martian system in the 2030s. Subsequent human and robotic missions to the asteroidal material would also be facilitated by its return to cislunar space. Although ARM is primarily a capability demonstration mission (i.e., technologies and associated operations), there exist significant opportunities to advance our knowledge of small bodies in the synergistic areas of science, planetary defense, asteroidal resources and in-situ resource utilization (ISRU), and capability and technology demonstrations. In order to maximize the knowledge return from the mission, NASA is organizing an ARM Investigation Team, which is being preceded by the Formulation Assessment and Support Team. These teams will be comprised of scientists, technologists, and other qualified and interested individuals to help plan the implementation and execution of ARM. An overview of robotic and crewed segments of ARM, including the mission requirements, NEA targets, and mission operations, will be provided along with a discussion of the potential opportunities associated with the mission.

Description: The Apollo missions collected 382 kg of rock and regolith from the Moon; approximately 1/3 of the sample mass collected was regolith. Lunar regolith consists of well mixed rocks, minerals, and glasses less than 1-centimeter n size. The majority of most surface regolith samples were sieved into less than 1, 1-2, 2-4, and 4-10- millimiter size fractions; a portion of most samples was re-served unsieved. The initial characterization and classification of most Apollo regolith particles was done primarily by binocular microscopy. Optical classification of regolith is difficult because (1) the finest fraction of the regolith coats and obscures the textures of the larger particles, and (b) not all lithologies or minerals are uniquely identifiable optically. In recent years, we have begun to use more modern x-ray beam techniques [1-3], coupled with high resolution 3D optical imaging techniques [4] to characterize Apollo and meteorite samples as part of the curation process. These techniques, particularly in concert with SEM imaging of less than 1-millimeter regolith grain mounts, allow for the rapid characterization of the components within a regolith.

Description: Evolved Gas Analysis (EGA), which involves heating a sample and monitoring the gases released, has been performed on Mars by the Viking gas chromatography/mass spectrometry instruments, the Thermal and Evolved Gas Analyzer (TEGA) on the Phoenix lander, and the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory. All of these instruments detected CO2 released during sample analysis at abundances of approx. 0.1 to 5 wt% assuming a carbonate source. The source of the CO2 can be constrained by evaluating the temperature of the gas release, a capability of both the TEGA and SAM instruments. The samples analyzed by SAM show that the majority of the CO2 is released below 400C, much lower than traditional carbonate decomposition temperatures which can be as low as 400C for some siderites, with magnesites and calcites decomposing at even higher temperatures. In addition to mineralogy, decomposition temperature can depend on particle size (among other factors). If carbonates formed on Mars under low temperature and relative humidity conditions, the resulting small particle size (nanophase) carbonates could have low decomposition temperatures. We have found that calcite can be synthesized by exposing CaO to water vapor and CO2 and that the resulting mineral has an EGA peak of approx. 550C for CO2, which is about 200C lower than for other calcites. Work is ongoing to produce Fe and Mg-bearing carbonates using the same process. Current results suggest that nanophase calcium carbonates cannot explain the CO2 released from martian samples. If the decomposition temperatures of Mg and Fe-bearing nanophase carbonates are not significantly lower than 400C, other candidate sources include oxalates and carboxylated organic molecules. If present, the abundance of organic carbon in these samples could be greater than 0.1 wt % (1000s of ppm), a signficant departure from the paradigm of the organic-poor Mars based on Viking results.

Description: Comets and asteroids are subjected to extremely cold conditions throughout their lifetimes. During their sojourns in the solar system, they are subjected to collisions at speeds that are easily capable of generating shock waves in their constituent materials. In addition to ices, more common silicate minerals such as olivines and pyroxenes are important components of these objects. The collision-induced shocks could affect the spectral signatures of those mineral components, which could in turn be detected telescopically. We have embarked on a project to determine how impact-generated shock might affect the reflectance spectra and structures of select silicates as both impact speed and target temperature are varied systematically. While the effects of impact speed (in the form of shock stress) on numerous materials have been and continue to be studied, the role of target temperature has received comparatively little attention, presumably because of the operational difficulties it can introduce to experimentation. Our experiments were performed with the vertical gun in the Experimental Impact Laboratory of the Johnson Space Center. A liquid-nitrogen system was plumbed to permit cooling of the target container and its contents under vacuum to temperatures as low as -100 C (173 K). Temperatures were monitored by thermocouples mounted on the outside of the target container. Because those sensors were not in contact with the target material at impact, the measured temperatures are treated as lower limits for the actual values. Peridot (Mg-rich olivine) and enstatite (Mg-rich orthopyroxene) were used as targets, which involved the impact of alumina (Al2O3) spheres at speeds of 2.0 - 2.7 km s(exp -1) and temperatures covering 25 C to -100 C (298 K to 173 K). We have begun collecting and analyzing data in the near to mid-IR with a Fourier-transform infrared spectrometer, and preliminary analyses show that notable differences in absorption-band strength and position occur as functions of both impact speed (peak shock stress) and initial temperature.

Description: The OSIRIS-REx asteroid sample return mission will collect approximately150 g of material from carbonaceous asteroid Bennu and return it to Earth in 2023. The sample will be curated along with NASA's other astromaterials sample collections at Johnson Space Center (JSC) in Houston. As part of the mission planning, JSC will be engaged in the following four general activities.

Description: Everything we know about sedimentary processes on Mars is gleaned from remote sensing observations. Here we report insights from meteorite Northwest Africa (NWA) 7034, which is a water-rich martian regolith breccia that hosts both igneous and sedimentary clasts. The sedimentary clasts in NWA 7034 are poorly-sorted clastic siltstones that we refer to as protobreccia clasts. These protobreccia clasts record aqueous alteration process that occurred prior to breccia formation. The aqueous alteration appears to have occurred at relatively low Eh, high pH conditions based on the co-precipitation of pyrite and magnetite, and the concomitant loss of SiO2 from the system. To determine the origin of the NWA 7034 breccia, we examined the textures and grain-shape characteristics of NWA 7034 clasts. The shapes of the clasts are consistent with rock fragmentation in the absence of transport. Coupled with the clast size distribution, we interpret the protolith of NWA 7034 to have been deposited by atmospheric rainout resulting from pyroclastic eruptions and/or asteroid impacts. Cross-cutting and inclusion relationships and U-Pb data from zircon, baddelleyite, and apatite indicate NWA 7034 lithification occurred at 1.4-1.5 Ga, during a short-lived hydrothermal event at 600-700 C that was texturally imprinted upon the submicron groundmass. The hydrothermal event caused Pb-loss from apatite and U-rich metamict zircons, and it caused partial transformation of pyrite to submicron mixtures of magnetite and maghemite, indicating the fluid had higher Eh than the fluid that caused pyrite-magnetite precipitation in the protobreccia clasts. NWA 7034 also hosts ancient 4.4 Ga crustal materials in the form of baddelleyites and zircons, providing up to a 2.9 Ga record of martian geologic history. This work demonstrates the incredible value of sedimentary basins as scientific targets for Mars sample return missions, but it also highlights the importance of targeting samples that have not been overprinted by metamorphic processes, which is the case for NWA 7034.

Description: The Mars Exploration Rover Opportunity has been traversing the rim of the Noachianaged, 22 km diameter Endeavour crater. Circa sol 3390 of its mission, Opportunity reached the northern tip of the rim segment known as Solander Point and has since been traversing the rim to the south to its current location at the break in the rim known as Marathon Valley. The rocks making up the rim are dominated by impact breccias consisting of clasts and a finergrained matrix. Several segments of the rim are transected by fractures as observed from orbital HiRISE imagery. Pancam multispectral observations of outcrop in these fracture regions, including part of the rim crest dubbed Murray Ridge, the Hueytown fracture, and Marathon Valley have been made. Over the range of 430 to 1010 nm there are changes in the multispectral reflectance signature of the breccia matrix with an increase in 535 nm and 904 nm band depth. This is attributed to oxidation and an increase in ferric oxides in these areas. In situ observations by the rover's APXS also indicate chemical differences associated with the matrix along these fractures, including increasing Fe/Mn southward from Solander Point to a region having an AlOH signature in CRISM spectra, and generally higher SO3 in the Hueytown fracture region and the area around Spirit of St. Louis. Overturned rocks observed on Murray Ridge were determined by the APXS to have elevated Mn and Pancam spectra of the high Mn spots have a characteristic red, featureless slope. This spectrum was also observed in association with some coatings on blocks of the sulfaterich Grasberg formation. Spectra resembling red hematite are observed in some zones in association with the craterform feature Spirit of St. Louis outside the mouth (to the west) of Marathon Valley. Marathon Valley itself has been observed from orbital hyperspectral observations by the CRISM sensor to host occurrences of Fe/Mg smectite minerals indicating extensive aqueous alteration in this region. Pancam observations in Marathon Valley will play an important role in surveying outcrop and making VNIR spectral comparisons with clay bearing outcrop examined earlier in the mission at the Matijevic Hill region.

Description: Endeavour crater (2.28 deg S, 354.77 deg E) is a Noachian-aged 22 km-diameter impact structure of complex morphology in Meridiani Planum. The degradation state of the crater has been studied using Mars Reconnaissance Orbiter and Opportunity rover data. Exposed rim segments rise approximately 10 m to approximately 100 m above the level of the embaying Burns Formation and the crater is 200-500 m deep with the southern interior wall exposing over approximately 300 m relief. Both pre-impact rocks (Matijevic Formation) and Endeavour impact ejecta (Shoemaker Formation) are present at Cape York, but only the Shoemaker crops out (up to approximately 140 m) along the rim segment from Murray Ridge to Cape Tribulation. Study of pristine complex craters Bopolu and Tooting, and morphometry of other martian complex craters, enables us to approximate Endeavour's pristine form. The original rim likely averaged 410 m (+/-)200 m in elevation and a 250-275 m section of ejecta ((+/-)50-60 m) would have composed a significant fraction of the rim height. The original crater depth was likely between 1.5 km and 2.2 km. Comparison between the predicted original and current form of Endeavour suggests approximately 100-200 m rim lowering that removed most ejecta in some locales (e.g., Cape York) while thick sections remain elsewhere (e.g., Cape Tribulation). Almost complete removal of ejecta at Cape York and minimal observable offset across fractures indicates current differences in rim relief are not solely due to original rim relief. Rim segments are embayed by approximately 100-200 m thickness of plains rocks outside the crater, but thicker deposits lie inside the crater. Ventifact textures confirm ongoing eolian erosion with the overall extent difficult to estimate. Analogy with degraded Noachian-aged craters south of Endeavour, however, suggests fluvial erosion dominated rim degradation in the Noachian and was likely followed by approximately 10s of meters modification by alternate processes. Such degradation is consistent with 1) the interpretation of a pediment on the rim flanks of Endeavour, 2) the formation of features such as Marathon Valley, 3) the nearly complete removal of ejecta at Cape York, 4) preservation of a thicker section of ejecta at Cape Tribulation and perhaps, 5) the origin of some gaps in the rim around the crater. A paucity of debris shed from the rim indicates most degradation occurred prior to embayment by the plains rocks.

Description: The Sample Analysis at Mars (SAM) instrument detected at least 4 distinct CO2 release during the pyrolysis of a sample scooped from the Rocknest (RN) eolian deposit. The highest peak CO2 release temperature (478-502 C) has been attributed to either a Fe-rich carbonate or nano-phase Mg-carbonate. The objective of this experimental study was to evaluate the thermal evolved gas analysis (T/EGA) characteristics of a series of terrestrial Fe-rich carbonates under analog SAM operating conditions to compare with the RN CO2 releases. Natural Fe-rich carbonates (〈53 microns) with varying Fe amounts (Fe(0.66)X(0.34)- to Fe(0.99)X(0.01)-CO3, where X refers to Mg and/or Mn) were selected for T/EGA. The carbonates were heated from 25 to 715 C (35 C/min) and evolved CO2 was measured as a function of temperature. The highest Fe containing carbonates (e.g., Fe(0.99)X(0.01)-CO3) yielded CO2 peak temperatures between 466-487 C, which is consistent with the high temperature RN CO2 release. The lower Fe-bearing carbonates (e.g., Fe(0.66)X(0.34)CO3) did not have peak CO2 release temperatures that matched the RN peak CO2 temperatures; however, their entire CO2 releases did occur within RN temperature range of the high temperature CO2 release. Results from this laboratory analog analysis demonstrate that the high temperature RN CO2 release is consistent with Fe-rich carbonate (approx.0.7 to 1 wt.% FeCO3). The similar RN geochemistry with other materials in Gale Crater and elsewhere on Mars (e.g., Gusev Crater, Meridiani) suggests that up to 1 wt. % Fe-rich carbonate may occur throughout the Gale Crater region and could be widespread on Mars. The Rocknest Fe-carbonate may have formed from the interaction of reduced Fe phases (e.g., Fe2+ bearing olivine) with atmospheric CO2 and transient water. Alternatively, the Rocknest Fe-carbonate could be derived by eolian processes that have eroded distally exposed deep crustal material that possesses Fe-carbonate that may have formed through metamorphic and/or metasomatic processes.

Description: Mars Exploration Rover Opportunity has been exploring Meridiani Planum for 11+ years, and is presently investigating the geology of rim segments of 22 km diameter, Noachian-aged Endeavour crater. The Alpha Particle X-ray Spectrometer has determined the compositions of a pre-impact lithology and impact breccias representing ejecta from the crater. Opportunity is now investigating the head (higher elevation, western end) of Marathon Valley. This valley cuts eastward through the central portion of the Cape Tribulation rim segment and provides a window into the lower stratigraphic record of the rim. At the head of Marathon Valley is a shallow (few 10s of cm), ovoid depression approximately 2736 m in size, named Spirit of Saint Louis, that is surrounded by approximately 20-30 cm wide zone of more reddish rocks (red zone). Opportunity has just entered a region of Marathon Valley that shows evidence for Fe-Mg smectite in Compact Reconnaissance Imaging Spectrometer for Mars spectra indicating areally extensive and distinct lithologic units and/or styles of aqueous alteration. Rocks at the head of Marathon Valley and within Spirit of Saint Louis are breccias (valley-head rocks). In some areas, layering inside Spirit of Saint Louis appears continuous with the rocks outside. The valley-head rocks are of similar, generally basaltic composition. The continuity in composition, texture and layering suggest the valley-head rocks are coeval breccias, likely from the Endeavour impact. These local breccias are similar in non-volatile-element composition to breccias investigated elsewhere on the rim. Rocks within the red zone are like those on either side in texture, but have higher Al, Si and Ge, and lower S, Mn, Fe, Ni and Zn as compared to rocks on either side. The valley-head rocks have higher S than most Endeavour rim breccias, while red zone rocks are like those latter breccias in S. Patches within the rocks outside Spirit of Saint Louis have higher Al, Si and Ge indicating red-zone-style alteration extended beyond the narrow red zone. Rocks on either side of the red zone and patches within it have the multispectral signature (determined by Panoramic Camera) of red hematite indicating an oxidizing environment. The red zone appears to be a thin alteration zone marking the border of Spirit of Saint Louis, but the origin of this morphologic feature remains obscure.

Description: Six Apollo missions landed on the Moon from 1969-72, returning to Earth 382 kg of lunar rock, soil, and core samples-among the best documented and preserved samples on Earth that have supported a robust research program for 45 years. From mission planning through sample collection, preliminary examination, and subsequent research, strict protocols and procedures are followed for handling and allocating Apollo subsamples. Even today, 100s of samples are allocated for research each year, building on the science foundation laid down by the early Apollo sample studies and combining new data from today's instrumentation, lunar remote sensing missions and lunar meteorites. Today's research includes advances in our understanding of lunar volatiles, lunar formation and evolution, and the origin of evolved lunar lithologies. Much sample information is available to researchers at curator.jsc.nasa.gov. Decades of analyses on lunar samples are published in LPSC proceedings volumes and other peer-reviewed journals, and tabulated in lunar sample compendia entries. However, for much of the 1969-1995 period, the processing documentation, individual and consortia analyses, and unpublished results exist only in analog forms or primitive digital formats that are either inaccessible or at risk of being lost forever because critical data from early investigators remain unpublished. We have initiated several new efforts to rescue some of the early Apollo data, including unpublished analytical data. We are scanning NASA documentation that is related to the Apollo missions and sample processing, and we are collaborating with IEDA to establish a geochemical database called Moon DB. To populate this database, we are working with prominent lunar PIs to organize and transcribe years of both published and unpublished data. Other initiatives include micro-CT scanning of complex lunar samples to document their interior structure (e.g. clasts, vesicles); linking high-resolution scans of Apollo film products to samples; and new procedures for systematic high resolution photography of samples before additional processing, enabling detailed 3D reconstructions of the samples. All of these efforts will provide comprehensive access to Apollo samples and support better curation of the samples for decades to come.

Description: The US Antarctic meteorite program has re-covered 〉21,000 meteorites since 1976, with thousands of those recovered from several icefields over multiple seasons, some-times spanning over a decade [1]. Pairing is assigned as best as possible at the time of classification, based on information from the field team, macro-scale hand sample features in the lab, and petrography, but later focused studies can reveal details that suggest re-evaluation of pairing groups. As a result, pairing groups are revealed over time, and must be continuously updated. Here we examine a few groups with known issues and give an update on some of the larger or more significant pairing groups.

Description: Recent models for accretion of terrestrial bodies involve metal-silicate equilibrium as the metallic core formed during growth. Most elements considered are either refractory or well studied elements for which effects of pressure, temperature, oxygen fugacity, and metallic liquid composition are well known. There are a large number of elements that are both siderophile and volatile, whose fate in such models is unknown, largely due to a lack of data at comparable conditions and com-positions (FeNi core with light elements such as S, C, Si, and O). We have focused on Ge, In, As, Sb and determined the effect of Si and C on metal-silicate partitioning, and developed a thermo-dynamic model that allows application of these new data to a wide range of planetary bodies. New experiments: We have previously carried out experiments with FeSi metallic liquid at C-saturated conditions at 1600 and 1800 C [4]. In a new series of experiments we investigate the effect of Si in carbon-free systems at 1600 C for comparison. Experiments were carried out at 1 GPa in MgO capsules using the same basaltic starting composition as in previous studies. The MgO capsule reacts with the silicate melt to form more MgO-rich liquids that have 22-26 wt% MgO. Experimental met-als and silicates were analyzed using a combination of electron microprobe analysis and laser ablation ICP-MS. Results: The new results can be interpreted by considering Ge as an example, in the simple exchange equilibrium Fe + GeO = FeO + Ge, where the equilibrium constant Kd can be examined as a function of Si content of the metal. The slope of lnKd vs. (1-XSi) for this new series allows derivation of the epsilon interaction parameter for each of these four elements and Si (both C-saturated and C-free).All four elements have positive epsilon values, indicating that Si causes a decrease in the partition coefficients; values are 6.6, 6.5, 27.8 and 25.2 for In, Ge, As, and Sb, respectively, at 1 GPa and 1600 C. As an example of how large the effect of Si can be, these epsilon values correspond to activity coefficients (gamma) for As of 0.01 when XSi = 0, and up to gamma = 23 when XSi = 0.2. Combining these new results with previous determinations [5,6] of epsilon parameters for S and C for these elements allows us calculate activity of Ge, In, As, and Sb in Fe-Ni-Si-S-C-O metallic liquids. We apply this new model to sever-al terrestrial bodies such as Earth (Si-rich core), Mars (S-rich core), Moon (S-, C-, and Si-poor core), and Vesta, and examine the resulting core and mantle concentrations of these elements. Mantle concentrations of these four elements are well explained for Earth and Mars in models that call for mid-mantle equilibration between Si-bearing and S-bearing FeNi cores, respectively. Modeling results for the Moon and Vesta will also be presented.

Description: Geochemically-depleted shergottites are basaltic rocks derived from a martian mantle source reservoir. Geochemical evolution of the martian mantle has been investigated mainly based on the Rb-Sr, Sm-Nd, and Lu-Hf isotope systematics of the shergottites [1]. Although potentially informative, U-Th- Pb isotope systematics have been limited because of difficulties in interpreting the analyses of depleted meteorite samples that are more susceptible to the effects of near-surface processes and terrestrial contamination. This study conducts a 5-step sequential acid leaching experiment of the first witnessed fall of the geochemically-depleted olivinephyric shergottite Tissint to minimize the effect of low temperature distrubence. Trace element analyses of the Tissint acid residue (mostly pyroxene) indicate that Pb isotope compositions of the residue do not contain either a martian surface or terrestrial component, but represent the Tissint magma source [2]. The residue has relatively unradiogenic initial Pb isotopic compositions (e.g., 206Pb/204Pb = 10.8136) that fall within the Pb isotope space of other geochemically-depleted shergottites. An initial -value (238U/204Pb = 1.5) of Tissint at the time of crystallization (472 Ma [3]) is similar to a time-integrated mu- value (1.72 at 472 Ma) of the Tissint source mantle calculated based on the two-stage mantle evolution model [1]. On the other hand, the other geochemically-depleted shergottites (e.g., QUE 94201 [4]) have initial -values of their parental magmas distinctly lower than those of their modeled source mantle. These results suggest that only Tissint potentially reflects the geochemical signature of the shergottite mantle source that originated from cumulates of the martian magma ocean

Description: On July 14, 2015, after a 9.5 year trek across the solar system, NASA's New Horizons spacecraft flew by the dwarf planet Pluto and its system of moons, taking imagery, spectra and in-situ particle data. Data from New Horizons will address numerous outstanding questions on the geology and composition of Pluto and Charon, plus measurements of Pluto's atmosphere, and provide revised understanding of the formation and evolution of Pluto and Charon and its smaller moons. This data set is an invaluable glimpse into the outer Third Zone of the solar system. Data from the intense July 14th fly-by sequence will be downlinked to Earth over a period of 16 months, the duration set by the large data set (over 60 GBits) and the limited transmitted bandwidth rates (approx. 1-2 kbps) and sharing the three 70 m DSN assets with our missions. The small fraction (approx. 1%) of data downlinked during the early phase of the flyby has already revealed Pluto and Charon to be very different worlds, with increasing and dynamic complexity.

Description: The flux of kilogram-sized meteoroids has been determined from the first 5 years of observations by NASA's Lunar Impact Monitoring Program (Suggs et al. 2014). Telescopic video observations of 126 impact flashes observed during photometric conditions were calibrated and the flux of meteoroids to a limiting mass of 30 g was determined to be 6.14 x 10(exp -10) m(exp -2) yr(exp -1) at the Moon, in agreement with the Grun et al. (1985) model value of 7.5 x 10(exp -10) m(exp -2) yr(exp -1). After accounting for gravitational focusing effects, the flux at the Earth to a limiting impact energy of 3.0 x10(exp -6) kilotons of TNT (1.3 x 10(exp 7) J) was determined to be consistent with the results in Brown et al. (2002). Approximately 62% of the impact flashes were correlated with major meteor showers as cataloged in visual/optical meteor shower databases. These flux measurements, coupled with cratering and ejecta models, can be used to develop impact ejecta engineering environments for use in lunar surface spacecraft design and risk analyses.

Description: Since early 2006, NASA's Marshall Space Flight Center (MSFC) has observed over 330 impact flashes on the Moon, produced by meteoroids striking the lunar surface. On 17 March 2013 at 03:50:54.312 UTC, the brightest flash of a 9-year routine observing campaign was observed by two 0.35 m telescopes at MSFC. The camera onboard the Lunar Reconnaissance Orbiter (LRO), a NASA spacecraft mapping the Moon from lunar orbit, discovered the fresh crater associated with this impact [1] approximately 3 km from the location predicted by a newly developed geolocation technique [2]. The meteoroid impactor responsible for this event may have been part of a stream of large particles encountered by the Earth/Moon associated with the Virginid Meteor Complex, as evidenced by a cluster of five fireballs seen in Earth's atmosphere on the same night by the NASA All Sky Fireball Network [3] and the Southern Ontario Meteor Network [4]. Crater size calculations based on assumptions derived from fireball measurements yielded an estimated crater diameter of 10-23 m rim-to-rim using the Holsapple [5] and Gault [6] models, a result consistent with the observed crater measured to be 18 m across. This is the first time a lunar impact flash has been associated with fireballs in Earth's atmosphere and an observed crater.

Description: Chondrites are among the most primitive surviving materials from the early solar system. They are divided into groups based on chemical types defined by mineralogy, bulk composition, and oxygen isotope compositions. Chondrites range in petrographic grade from type 1 to type 7. Type 3 chondrites are the most primitive and are little changed from the nebular solids accreted to form asteroids. They are composed of chondrules, fine-grained matrix, metal and sulfide, plus or minus Ca-Al-rich inclusions. With increasing aqueous alteration at low temperatures, members of some chondrite classes transformed from type 3 towards type 1. With increasing thermal metamorphism and low fluid content, members of other classes changed from type 3 towards type 7. Rumuruti (R) chondrites are a rare group (0.1% of falls) similar to ordinary chondrites in some properties but different in others. They are characterized by low chondrule/matrix modal abundance ratios, high oxidation state, small mean chondrule size, abundant sulfides and low metal contents. R chondrites vary in petrologic type from 3 to 6. They are important objects to study because some of them have undergone metamorphism at high temperatures in the presence of aqueous fluids. In contrast, CM and CI chondrites were heated to low temperatures in the presence of aqueous fluids leading to alteration; they contain low-T hydrous phases (phyllosilicates) and little or no remaining metal. Ordinary chondrites were heated to high temperatures in a low-fluid environment resulting in anhydrous metamorphic rocks. R6 chondrites are highly metamorphosed and some contain the high-T hydrous phases mica and amphibole. R chondrites are thus unique and give us an opportunity to examine whether there are compositional effects caused by high-T, highfluid metamorphism of nebular materials.

Description: The Opportunity rover has traversed portions of two western rim segments of Endeavour, a 22 km-diameter crater in Meridiani Planum, for the past three years. The resultant data enables the evaluation of the geologic expression and degradation state of the crater. Endeavour is Noa-chian-aged, complex in morphology, and originally may have appeared broadly similar to the more pristine 20.5 km-diameter Santa Fe complex crater in Lunae Palus (19.5degN, 312.0degE). By contrast, Endeavour is considerably subdued and largely buried by younger sulfate-rich plains. Exposed rim segments dubbed Cape York (CY) and Solander Point/Murray Ridge/Pillinger Point (MR) located approximately1500 m to the south reveal breccias interpreted as remnants of the ejecta deposit, dubbed the Shoemaker Formation. At CY, the Shoemaker Formation overlies the pre-impact rocks, dubbed the Matijevic Formation.

Description: Space weathering processes such as solar wind irradiation and micrometeorite impacts are known to alter the the properties of regolith materials exposed on airless bodies. The rates of space weathering processes however, are poorly constrained for asteroid regoliths, with recent estimates ranging over many orders of magnitude. The return of surface samples by JAXA's Hayabusa mission to asteroid 25143 Itokawa, and their laboratory analysis provides "ground truth" to anchor the timescales for space weathering processes on airless bodies. Here, we use the effects of solar wind irradiation and the accumulation of solar flare tracks recorded in Itokawa grains to constrain the rates of space weathering and yield information about regolith dynamics on these timescales.

Description: The Curiosity rover traverse in Gale crater has explored a large series of sedimentary deposits in an ancient lake on Mars. Over the nine kilometers of traverse a recurrent observation has been southward-dipping sedimentary strata, from Shaler at the edge of Yellowknife Bay to the striated units near the Kimberley. Within the sedimentary strata cm- to decimeter- size hollow spheroidal objects and some apparent cylindrical objects have been observed. These features have not been seen by previous landed missions. The first of these were observed on sol 122 in the Gillespie Lake member at Yellowknife Bay. Additional hollow features were observed in the Point Lake outcrop in the same area. More recently a spherical and apparently hollow object, Winnipesaukee, was observed by ChemCam and Mastcam on sol 653. Here we describe the settings, morphology, and associated compositions, and we discuss possible origins of these objects.

Description: A number of new instrument capabilities are currently in maturation for future in situ use on planetary science missions. Moving beyond the impressive in situ instrumentation already operating in planetary environments beyond Earth will enable the next step in scientific discovery. The approach for developing beyond current instrumentation requires a careful assessment of science-driven capability advancement. To this end, two examples of instrument technology development efforts that are leading to new and important analytical capabilities for in situ planetary science will be discussed: (1) an instrument prototype enabling the interface between liquid separation techniques and laser desorption/ionization mass spectrometry and (2) an addressable excitation source enabling miniaturized electron probe microanalysis for elemental mapping of light and heavy elements.

Description: No abstract available

Description: No abstract available

Description: Carbonaceous chondrites (CC) preserve a diverse range of organic matter formed within cold interstellar environments, the solar nebula, and during subsequent parent body asteroidal processing. This organic matter maintains a unique geochemical and istopic record of organic evolution [1-4]. Bulk studies of organics within CC have revealed a complex array of organic species. However, bulk studies invariably involve solvent extraction, resulting in a loss of spatial context of the host mineral matrix [3, 5]. Correlated in situ chemical and isotopic studies suggest preservation of interstellar organics in the form of spherical, often hollow, micrometer sized organic nano-globules. Nanoglobules often exhibit significant delta 15N and delta D enrichments that imply formation through fractionation of ion-molecule reactions within cold molecular clouds and/or the outer protoplanetary disk [5]. In situ studies such as 6-8 are necessary to understand the organic evolutionary stages of nanoglobules and other components in the nebula and parent body [7]. We carried out coordinated in situ micrometer-scale chemical, mineralogical and isotopic studies of the Murchison (CM2), QUE 99177 (CR3), and Tagish Lake (C2 Ung) CC. These studies were performed using fluorescent microscopy, two-step laser mass spectrometry (microL2MS), NanoSIMS, and Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Spectroscopy (EDX). Comparative analysis of three different meteorites will help reveal the effects of parent body processes on the chemistry and isotopic composition of organic matter.

Description: The occurrence of extensive valley networks and layered deposits of phyllosilicates and sulfates during the late Noachian/Hesperian periods (approx. 3-4 Gyrs) indicates a past martian climate that was capable of maintaining liquid water at the surface. The planets climate drastically changed after these early episodes of water to a drier and colder environment during the Amazonian period (past 3.0 Gyrs). The objective of this paper is to describe aqueous alteration/weathering scenarios on Mars based on observations returned by rover and lander missions. The chemistry of most outcrops, rocks, and soils that have interacted with water has not been extensively changed from average Mars crustal basaltic composition. Little chemical variation suggests closed hydrologic systems were prominent on early Mars and/or the water/rock ratios were low. Open hydrologic systems occur at local scales, e.g., high Si and Ti rocks and soil deposits around a volcanic feature in Gusev crater. Geochemical and mineralogical indicators for aqueous alteration include jarosite and other Fe-sulfates at several locations suggesting acid-sulfate alteration conditions. High Si and Ti rocks, sediments, and soil deposits are consistent with basaltic residues extenively leached by extremely acidic fluids. Variations in the Fe/Mn ratio of fracture veins infilled with sulfate-rich materials suggest changes in redox and/or pH conditions of the migrating fluids. The increase of nanophase iron oxides and salts with depth in several soil pits escavated by the Spirit rovers wheel in Gusev crater suggests the translocation/mobolization of these phases by liquid water. This pedogenic process is the result of limited water movement through the surface sediments during the Amazonian period; however, it is likely that paleosols exist on Mars that formed during the early wetter history of the planet. Soil scientists have the opportunity to continue to (and should) be involved in the exploration of the Red planet.

Description: We describe the current state of knowledge about Mercury's interior structure. We review the available observationalconstraints, including mass, size, density, gravity eld, spin state, composition, and tidal response. These data enablethe construction of models that represent the distribution of mass inside Mercury. In particular, we infer radial prolesof the pressure, density, and gravity in the core, mantle, and crust. We also examine Mercury's rotational dynamicsand the inuence of an inner core on the spin state and the determination of the moment of inertia. Finally, we discussthe wide-ranging implications of Mercury's internal structure on its thermal evolution, surface geology, capture in aunique spin-orbit resonance, and magnetic eld generation.

Description: A one-day workshop was held at NASA Ames Research Center, January 16, 2018, to re-examine the 1908 Tunguska impact using modern computational tools, many of them developed in response to the 2013 Chelyabinsk airburst. Twelve international experts gave presentations, with another 40 attending in-person or remotely. The most likely models for Tunguska converged on an energy of 10-20 Megatons, released in an airburst at a height of about 10 km. If the Tunguska impactor was a stony asteroid similar to Chelyabinsk, the diameter was roughly 50-80m. A comparison with current understanding of the population of asteroids in this size range indicates that the interval between such events is millennia, not centuries as had been concluded previously. The primary constraints on our understanding of Tunguska are the dearth of quantitative data, not weakness of the computational models. The workshop was sponsored by the NASA Ames Asteroid Threat Assessment Project and supported the NASA Planetary Defense Coordination Office.

Description: Seismicity models for Mars usually estimate the long-term average annual seismic moment rate, and also the average annual event rate. This holds for estimations based on geological evidence (Golombek et al., 1992, Golombek, 2002, Taylor et al., 2013) as well as for models based on thermal evolution and cooling of the Martian interior (Phillips, 1991, Knapmeyer et al., 2006, Plesa et al., 2018). All studies are compatible with the conclusion based on the non-observation of any unambiguous event by Viking (Anderson et al., 1977, Goins & Lazarewicz, 1979) that Martian seismicity lies somewhere between that of the Moon and that of the Earth. We developed tools to derive reasonable estimations of the annual seismic moment rate from a number of events as small as one, provided that the observed events are beyond the global completeness threshold for observable events. Numerical tests as well as evaluation of terrestrial data shows the feasibility of the approach.

Description: The National Aeronautics and Space Administration (NASA) has initiated a new Planetary Defense research activity, led by the NASA Ames Research Center. The objective of the effort is to provide tools for reliably assessing the impact damage that Potentially Hazardous Asteroids (PHAs) could inflict on the Earth. This research will support decisions regarding appropriate mitigation action in the event that an impact threat is discovered. The activity includes four interrelated tasks: PHA characterization, physics-based simulations of atmospheric entry breakup, simulations of surface damage due to airbursts, land impacts, or tsunamis, and an integrated assessment of the overall risks posed by potential PHA strikes. This paper outlines the objectives, research approaches, products, and interrelations of the activity's four tasks, and presents an overview of their current progress and preliminary results. Companion papers in this conference provide additional details of the work in the four task areas.

Description: Pluto was discovered in 1930 at Lowell Observatory in the belated resumption of a wide-field photographic search originally be-gun at Percival Lowells direction prior to his death in 1916. Photometry in the 1950s established the rotation period of 6.4 hours and a color redder than the Sun, but the mass, density, size and albedo were unknown. Near-infrared photometry in 1976 indicated the presence of CH4 frost, suggestive of a relatively high surface albedo and a diameter comparable to the Moon. The large satellite Charon was discovered in 1978, followed by an epoch of mutual transits and occultations of Pluto and Charon from 1985 to 1990, as viewed from Earth. These events resulted in reliable sizes and masses of the two bodies, as well as the orbit of Charon. The mutual events also demonstrated that Pluto and Charon are in locked synchronous rotation and revolution, a configuration unique among the planets. The atmosphere of Pluto was discovered in 1988 from a stellar occultation observed from the Kuiper Airborne Observatory and ground stations, with indications of a haze layer (or a temperature inversion) in the lower atmosphere. Sub-sequent stellar occultations showed that the extent of the atmosphere is variable on a timescale of a few years. The spectroscopic detection of N2 and CO ice in 1993 demonstrated that the atmosphere must be primarily composed of N2, with CH4 and CO as minor components; the spectroscopic detection of gaseous CH4 was reported in 1994.

Description: The National Aeronautics and Space Administration (NASA) has initiated a new Planetary Defense research activity, led by the NASA Ames Research Center. The objective of the effort is to provide tools for reliably assessing the impact damage that Potentially Hazardous Asteroids (PHAs) could inflict on the Earth. This research will support decisions regarding appropriate mitigation action in the event that an impact threat is discovered. The activity includes four interrelated tasks: PHA characterization, physics-based simulations of atmospheric entry/breakup, simulations of surface damage due to airbursts, land impacts, or tsunamis, and an integrated assessment of the overall risks posed by potential PHA strikes. This paper outlines the objectives, research approaches, products, and interrelations of the activitys four tasks, and presents an overview of their current progress and preliminary results. Companion papers in this conference provide additional details of the work in the four task areas.

Description: With the recent estimate of Mercury's surface composition from the X-Ray Spectrometer and Gamma-Ray Spectrometer that were onboard NASA's MErcury Surface, Space ENvironment, Geochemistry and Ranging (MESSENGER) spacecraft, we now have our first opportunity to directly investigate the compositions of lavas from the planet Mercury and indirectly investigate the chemical make-up of its interior. Results from MESSENGER showed exotic surface compositions with more than 3 wt% sulfur in some lavas and relatively low amounts of iron (less than 3 wt%) across the surface. These striking features are consistent with magmatism occurring under highly reducing conditions which has an impact on the thermal and chemical evolution of a planetary body. Here we'll explore the geochemical evolution of Mercury through a series of experimental studies and discuss the implications of low oxygen fugacity on elemental behavior and magmatic processes.

Description: Mars Ascent Vehicle (MAV) Study: Design challenges associated with Mars; Remote; Temperature; Atmosphere; Radiation; Dust. Challenges unique to MAV: No vehicle has ever left the surface of Mars; Completely autonomous; Physical system extremely limited; Martian environment creates a number of issues with traditional propulsion systems.

Description: Exploration of our Solar System has revealed a number of locations that are now habitable or could have supported life in the past. One approach to finding life involves detection of informational polymers like deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) that are definitive biosignatures for life as we know it. Alternatively, structural variants of DNA and RNA, collectively termed xenonucleic acids (XNAs) have been shown in the laboratory to behave similarly. Nanopore-based sequencers differ from traditional sequencing technologies in that they do not explicitly require synthesis of DNA before or during analysis. Because of this, nanopore sequencers have been used for the direct sequencing of RNA, and could be used for the detection and analysis of other charged polymers. Here we describe results of exposing the MinION hardware, flow cells, and key reagents to ionizing radiation at doses relevant to Mars and Europa missions (10 to 3000 silicon-equivalent gray).

Description: An overview of three missions connected with NASA's Goddard Space Flight Center at the present time: (1) NASA's flagship mission, the James Webb Space Telescope, is nearing its 2021 launch date. The James Webb, which is considered the successor to the Hubble Space Telescope, will orbit at the Earth-Sun Lagrangian Point Two where it will peer back in time, using infrared detectors, to the beginnings of our Universe. (2) NASA is conducting pioneering work in the field of robotic satellite servicing in earth orbit. The RESTORE-L project, which is slated for a 2021 launch date, is expected to pave the way for the inception of robotic assembly for deep space exploration as well as the commercialization of satellite servicing. (3) The Transiting Exoplanet Survey Satellite (TESS) has been orbiting the Earth actively searching for new planets since April of 2018. The discoveries that TESS has made to-date have benefited from a careful characterization of the refractive lens assemblies on its science instruments. The presentation will provide a detailed description of how the index of refraction of the glasses used to fabricate the TESS lens assemblies were measured at Goddard to an accuracy that enables the ability to make exoplanet discoveries hundreds of light years from Earth.

Description: The Apollo program was undoubtable a crowning achievement in human history. In addition to the obvious cultural significance, scientific results from the Apollo program had a lasting impression on a range of scientific fields, none more so that the effect the samples had on the fields of geology and cosmochemistry. The six Apollo missions collected 382 kg of rock, regolith, and core samples from geologically diverse locations on the Moon. In the nearly 50 years since the first samples were returned, there have been over 3000 different requests for samples, each yielding insights into fields as disparate as biology, medicine, astronomy, engineering, material science, and of course geology. Early studies of the Apollo samples revealed primary insights into the origin and evolution of the Moon, and of the Earth-Moon system, but the results also had implications for bodies throughout the solar system, e.g., defining crater counting rates. Over the decades, continued study of the Apollo samples by new generations of scientists using new instruments have continued to yield significant new discoveries, including the presence of endogenous water in the Moon and the possible presence of a lunar cataclysm, that in turn has contributed to new models of solar system formation and evolution. The Apollo samples have often been used as a proxy for studying other bodies like Mercury or asteroids. The Apollo samples have also directly contributed to the interpretation of remotely sensed data sets, including their use as ground truth for both Clementine and Lunar Prospector global geochemical maps. Despite the Apollo samples being a static collection, recent efforts will ensure that investigators continue to have access to new samples. For example, there was a recent solicitation for study of previously unopened Apollo samples in vacuum-sealed containers, as well as new access to samples stored frozen or in a He atmosphere. Similarly, the use of X-ray computed tomography as part of the curation process is identifying new clasts within polymict breccias that are available for study. Finally, the MoonDB project is putting all previously published lunar geochemical analyses into a searchable database, which should facilitate new investigations.

Description: We derived new vector gradients based models of crustal magnetic field at the lunar surface with data from the Lunar Prospector (LP) satellite using two model parameterization approaches: a global set of 35820 1 spaced (~30 km) equal area monopoles at 20 km below the surface (OBrien and Parker, 1994; Olsen et al., 2017) and combined results of subsets of 100000 0.66 spaced monopoles at the same depth. We use the scheme of iteratively reweighted least-squares inversion to compute the initial model. Then the amplitudes of these monopoles are determined by minimizing the misfit to the components together with the global average of |Br| at the ellipsoid surface (i.e. applying a L1 model regularization of Br). In previous approaches using vector fields for modeling, we found that external field contamination leads to spurious anomalies in the downward continued field models even with stringent data selection criteria and ad-hoc noise removal techniques (e.g., satellites position in the Moons wake w.r.t. the solar wind and in the Earths magnetotail, internal/external dipoles fields removal, low-order polynomial removal, joint equivalent source cross-validation technique and visually removing remaining anomalous segments). On the other hand, with the use of gradients-only data (along-track first finite differences), we were able to completely bypass the ad-hoc techniques. Similar processing of Kaguya magnetic data, which have only higher altitude coverage over the most of the Moon except in the region of the South PoleAitken (SPA) basin, completely misses some of the anomalies seen in the Lunar Prospector data. The combined Lunar Prospector and Kaguya gradient-based models also severely degrade the derivation of the anomaly fields in many regions. Euler analysis of isolated anomaly features from the Reiner Gamma swirl suggests top depths of about 0.3 to 1.5 km and center depths of 10-14 km; in the region between Stein and Vallier craters north of the SPA basin our analysis suggests top depths of around 1.5 km and center depths of 13-15 km. With the spectral depth determination techniques, the SPA basin region yields depths to the base of magnetization ranging between 15 and 40 km. Three-dimensional modeling and the bulk magnetization determinations of the sources constrained by the Euler and spectral methods is underway.

Description: The Stimson formation is a basaltic eolian sandstone perched unconformably above the Mount Sharp group rocks in Gale crater, and it is exposed in a number of plateaus observed by the Mars Science Laboratory Curiosity rover. Despite being one of the least geochemically and mineralogically diverse units observed by the Curiosity rover, the Stimson formation is uniquely positioned to offer significant information about sand weathering and lithification processes on Mars because of two factors: (1) the Stimson formation is the only lithologic formation on Mars for which we have a modern analog, the basaltic eolian Bagnold dunes, and (2) Curiosity obtained 33 chemistry analyses of 18 unique targets with the Alpha-Particle X-ray Spectrometer and 2 mineralogical samples of unaltered Stimson sandstone (discounting samples of Stimson altered by late-stage fluid events). Comparison between the Stimson sandstone and the Bagnold sands yields clues to source rock and lithification processes on Mars, and differences between different Stimson samples reveal weathering trends affecting the ancient dune field.

Description: The Mars Science Laboratory Curiosity rover landed in Gale crater in August 2012 to characterize modern and ancient surface environments. Curiosity executed a two-phase campaign to study the morphology, activity, physical properties, and chemical and mineralogical composition of the Bagnold Dune Field, an active eolian dune field on the lower slopes of Aeolis Mons (Mount Sharp). Detectable aspects of dune sand mineralogy have been examined from orbit with the visible/short-wave infrared spectrometer CRISMand the thermal-infrared spectrometers THEMIS and TES. CRISM data demonstrate variations in plagioclase, pyroxene, and olivine abundances across the dune field. Curiosity analyzed sediments from two locations in the dune field to evaluate the causes of the mineralogical differences observed from orbit. The Gobabeb sample was collected from Namib Dune, a barchanoidal dune on the upwind margin of the dune field, and the Ogunquit Beach sample was collected from the Mount Desert Island sand patch located downwind from Namib. These samples were sieved to 〈150 m and delivered to the CheMin X-ray diffraction instrument for quantitative mineralogical analysis. CRISM-derived mineralogy of the Namib Dune and Mount Desert Island and CheMin-derived mineralogy of the Gobabeb and Ogunquit Beach samples can be used in a value-added manner to interpret grain segregation at the bedform to dune-field scale and evaluate contributions from local sediment sources. Models of CRISM data demonstrate that Mount Desert Island is more enriched in olivine and less enriched in plagioclase than Namib dune, suggesting that fine-grained mafic sediments are preferentially mobilized downwind. Curiosity data indicate olivine also forms a coarse lag on the lee sides of barchanoidal dunes. Minor abundances of hematite, quartz, and anhydrite and small differences in the crystal chemistry of plagioclase and pyroxene derived from CheMin data suggest that sediments from the underlying lacustrine rocks also contribute to the Bagnold sands.

Description: In 2012, the entry vehicle for the Mars Science Laboratory (MSL) mission was the largest and heaviest vehicle flown to another planet, designed to be able to withstand the largest heat fluxes in the Martian atmosphere ever attempted. The heatshield material that had been successfully used for all previous Mars missions had been baselined in the design, but during the development and qualification testing demonstrated catastrophic and unexplained failures. With only 10 months remaining before the original launch date, the TPS team led by NASA Ames designed and implemented a first-ever tiled, ablative heatshield. Highlights from MSL of the testing difficulties and innovations required to execute a new heatshield design will be presented, along with a sneak peak of the Mars 2020 mission.

Description: The Mars Science Laboratory (MSL) Curiosity rover landed at Gale crater in August 2012 with the goal of unravelling the climate and habitability history of ancient Mars. On its way to higher stratigraphic levels of Aeolis Mons, the crater's central mound, Curiosity crossed an active dune field informally named the Bagnold Dune Field. Curiosity's traverse through the Bagnold Dunes between December 2015 and April 2017 constituted the first in situ investigation of an active dune field on another planet. The scientific campaign at the dunes enabled a detailed study of martian eolian processes at scales that are unachievable from orbiter-based imagery, from the scale of compound bedforms down to those of individual sand grains. The eolian-science campaign was broadly divided into two main phases - a first-phase investigation near two barchan dunes along the northern trailing edge of the dune field, Namib and High Dunes, and a second-phase investigation farther south near a linear dune, the Nathan Bridges Dune, named after our beloved colleague and friend Nathan Bridges. In addition to these two phases, the Bagnold Dunes campaign included punctual investigations of isolated ripples and ripple fields further along the rover traverse away from the Bagnold Dune Field. The main goals of the scientific investigation at the Bagnold Dunes were two-fold: (I) developing a mechanistic understanding of martian eolian processes and rates from direct in situ observations of eolian structures and their dynamics, and (II) characterizing the physical properties and the chemical and mineral composition of eolian sands and dust on Mars. Significant advances in martian eolian science resulted from Curiosity's ground investigation of the active Bagnold Dunes. Altogether, results from the Bagnold Dunes campaign are key to understanding how the martian environment affects eolian processes, and will thus prove most useful to deciphering paleoenvironments from the martian eolian sedimentary record.

Description: Following the loss of two reaction wheels four years into its mission, the Kepler team was faced with reinventing an operational approach to continue to deliver compelling science using an unanticipated suite of actuators. Spacecraft thrusters were not designed for accurate pointing control, yet with only two reaction wheels, only two axes could be actively controlled. With solar pressure as the only disturbing force, and recognizing the innate symmetry of the spacecraft, the K2 mission points the spacecraft in the orbital plane for three months at a time, placing the antennas 90 from the earth. Mapping the solar balance ridge 70 M km from Earth, with limited communications and a reduced staff presented a significant operational challenge.

Description: The aubrites are a group of differentiated meteorites that formed in extremely reducing conditions, with oxygen fugacities (O2) ranging from ~2 to ~6 log units below the Iron-Wstite buffer. At these extreme conditions, elements that are lithophile (silica-loving) on Earth can behave as chalcophiles (sulfur-loving) or siderophiles (metal-loving), and FeO-poor silicates and exotic sulfides can form. Elemental partitioning among minerals at these conditions are still not well understood, thus studying aubrites could help better constrain elemental behavior. Only 30 aubrites exist; however, they display various textures, which can be difficult to identify in small samples. Identifying composite clasts can help in understanding the igneous history of the aubrite parent bodies. In order to distinguish different minerals and textures in larger samples, we use X-ray computed tomography (XCT), which is a useful, non-destructive analysis that can produce a 3D representation of a meteorite's textures, structures, and modal mineralogy. This study investigates the Norton County aubrite using XCT. Norton County is a fragmental impact breccia aubrite, and was an observed fall with a main mass of 1.1 tons. This large amount of material offers an opportunity to investigate a great volume of reduced, aubritic sample and study a more diverse variety of clasts. Here we report XCT results of two samples of Norton County (NC 15417) in order to constrain the 3D modal mineralogy of silicates, sulfides, and metals, and to identify unique clasts within the matrix.

Description: This poster describes early results of an experiment exploring the potential stratification of gases in the deep Venus atmosphere

Description: Atmospheric aerosols on Mars are critical in determining the nature of its thermal structure, its large-scale circulation, and hence the overall climate of the planet. We conduct multi-annual simulations with the latest version of the NASA Ames Mars global climate model (GCM), gcm2.3+, that includes a modernized radiative-transfer package and complex water-ice cloud microphysics package which permit radiative effects and interactions of suspended atmospheric aerosols (e.g., water ice clouds, water vapor, dust, and mutual interactions) to influence the net diabatic heating. Results indicate that radiatively active water ice clouds profoundly affect the seasonal and annual mean climate. The mean thermal structure and balanced circulation patterns are strongly modified near the surface and aloft. Warming of the subtropical atmosphere at altitude and cooling of the high latitude atmosphere at low levels takes place, which increases the mean pole-to-equator temperature contrast (i.e., "baroclinicity"). With radiatively active water ice clouds (RAC) compared to radiatively inert water ice clouds (nonRAC), significant changes in the intensity of the mean state and forced stationary Rossby modes occur, both of which affect the vigor and intensity of traveling, synoptic period weather systems. Such weather systems not only act as key agents in the transport of heat and momentum beyond the extent of the Hadley circulation, but also the transport of trace species such as water vapor, water ice-clouds, dust and others. The northern hemisphere (NH) forced Rossby waves and resultant wave train are augmented in the RAC case: the modes are more intense and the wave train is shifted equatorward. Significant changes also occur within the subtropics and tropics. The Rossby wave train sets up, combined with the traveling synoptic-period weather systems (i.e., cyclones and anticyclones), the geographic extent of storm zones (or storm tracks) within the NH. A variety of circulation features will be presented which indicate contrasts between the RAC and nonRAC cases, and which highlight key effects radiatively-active clouds have on physical and dynamical processes active in the current climate of Mars.

Description: The CO2 cycle is one of the three controlling climate cycles on Mars. One aspect of the CO2 cycle that is not yet fully understood is the existence of a residual CO2 ice cap that is offset from the south pole. Previous investigations suggest that the atmosphere could control the placement of the south residual cap (e.g., Colaprete et al., 2005). These investigations show that topographically forced stationary eddies in the south during southern hemisphere winter produce colder atmospheric temperatures and increased CO2 snowfall over the hemisphere where the residual cap resides. Since precipitated CO2 ice produces higher surface albedos than directly deposited CO2 ice, it is plausible that CO2 snowfall resulting from the zonally asymmetric atmospheric circulation produces surface ice albedos high enough to maintain a residual cap only in one hemisphere. Our current work builds on these initial investigations with a version of the NASA Ames Mars Global Climate Model (GCM) that includes a sophisticated CO2 cloud microphysical scheme. Processes of cloud nucleation, growth, sedimentation, and radiative effects are accounted for. Simulated results thus far agree well with the Colaprete et al. studythe zonally asymmetric nature of the atmospheric circulation produces enhanced snowfall over the residual cap hemisphere throughout much of the winter season. However, the predicted snowfall patterns vary significantly with season throughout the cap growth and recession phases. We will present a detailed analysis of the seasonal evolution of the predicted atmospheric circulation and snowfall patterns to more fully evaluate the hypothesis that the atmosphere controls the placement of the south residual cap.

Description: Wintertime transient baroclinic eddies in the northern midlatitudes of Mars were identified in Viking Lander 2 (VL2, 48.3N, 134.0E) surface pressure data back in the early 1980s. Here we report the results of an analysis of REMS surface pressure data acquired by the Curiosity Rover in Gale Crater (4.5S, 137.4E) that suggests the meridional scale of these eddies is so large that the disturbances in the surface pressure fields they create extend across the equator and into the southern hemisphere. A power spectrum analysis of the seasonally detrended REMS pressure data from Ls=240-280 shows dominant periods of ~ 6 sols and ~2.2 sols (though with greatly reduced power) which are close the dominant periods of the transient eddies observed by VL2 at this season. Analysis of the surface pressure fields from the Ames Mars GCM for the same season also shows dominant periods at the grid points closest to VL2 and Gale Crater similar to those observed. In the model, the disturbances responsible for these oscillations are eastward traveling baroclinic eddies whose amplitudes are greatest at northern mid latitudes at this season, but whose meridional extent does indeed extend into the low latitudes of the southern hemisphere. REMS appears to be seeing the signature of these eddies, not only for this season but for the early fall and late winter seasons as well. While orbital images of the so called flushing storms, which more closely correspond to the shorter period waves, show dust-lifting frontal systems that cross the equator, REMS data - even though acquired at a longitude of comparatively weak storm activity - provide the first in-situ evidence that northern hemisphere transient eddies can be detected at the surface in low latitudes of the southern hemisphere.

Description: NASA's Resource Prospector (RP) project intends to characterize the 3D distribution of volatiles in permanently shadowed regions at the lunar poles. One RP remote sensing instrument is a near-infrared spectrometer with an associated camera and radiometer, called the Near-InfraRed Volatile Spectrometer System (NIRVSS). In May 2016, NIRVSS, a Honeybee Robotics drill, and an Inficon mass spectrometer were placed in a vacuum chamber at Glenn Research Center. Also inside was a tube (1.2 m high x 25 cm diameter) filled with lunar simulant NU-LHT-3M, initially doped with a homogeneous water abundance of ~5%, chilled to cryogenic temperatures and exposed to a vacuum (~10e-6 Torr). During drilling, the NIRVSS instruments observed the cuttings pile as subsurface materials were emplaced on the surface. Spectral features associated with water ice, near 2000 and 3000 nm, were measured by the spectrometer during drilling. The spectral data documents development of a desiccated soil layer in the tube down to ~25-30 cm (confirmed by post-test soil analyses), formed during the initial pump down to vacuum. Drilling occurred in 10 cm segments, with the drill stem extracted and flutes brushed after each 10 cm depth. One exception to this was the 40 cm depth segment where the soil was delivered to a sample capture mechanism, and sealed for post-test analyses. To ~30 cm depth the greatest 2000 and 3000 nm signatures were associated with brushing of the drill flutes above the surface. At depths 〉40 cm the strongest ice signatures were associated with the drill clearing soil from the existing hole, or beginning to encounter new material. For these greater depths, brushing the flutes after extraction produced much weaker ice signatures than for shallower depths. This suggests that the soil may remain trapped in the exit funnel and is not emplaced on the surface. After each event creating strong ice signatures, these signatures decreased to near background levels in 5 minutes or less, due to surface exposure to vacuum.

Description: Geochronology: More than just rock ages. What are the constraints on the time evolution ofthe dynamic solar system? When did the outerplanets migrate and the asteroid belt lose mass? How did it affect other bodies at that time?

Description: Develop and incorporate a liquid water cycle into the NASA Ames Research Center (ARC) Mars Global Climate Model (GCM).

Description: Fifty years ago Apollo astronauts walked on the Moon to explore the geology and collect samples for Earth return. Several authors have discussed the strategic planning and training that enabled the Apollo successes, and assembled recommendations regarding todays lunar science objectives and astronaut training required to achieve those science goals. Since the 1980s, geoscience training for astronauts focused on observing the Earth from orbit. Today, we are building a geoscience training program to support informed Earth observations as well as the exploration culture for future human missions to the Moon and Mars. Our team partnered with JSCs crew training and astronaut offices to develop our 4-week geoscience program for the 2017 astronaut class. Because the astronauts have a variety of professional backgrounds, we provide a broad introduction to Earth and planetary sciences. But our prime focus is 2 weeks of intensive field work, a methodology introduced with the 2013 astronaut class. We completed the first half of the training a field trip to observe hurricane deposits along Galveston Bay; keynotes by Apollo colleagues highlighting Apollo experiences; a tightly-integrated week of introductory geology in the classroom followed by a week of fieldwork in the Rio Grande del Norte National Monument. The classroom included interactive map exercises that allowed the students to progressively build a base map of the field area that they used as a starting point for their week-long mapping exercise. We divided the class into small mapping groups to conduct their observations, mapping and interpretation of the geology. In addition to learning geological field work, our field training provided the platform for practicing expeditionary leadership, a key skill set valued by NASA for astronaut crews. Next summer the capstone fieldwork for the 2017 astronauts will include both mapping and rock sampling. Throughout the mapping, the class will collect additional data to help inform field and sampling decisions using diagnostic field instruments that are being tested in analog settings for their operational efficacy for future planetary exploration.

Description: No abstract available

Description: Absolute age determination isnecessary to check and calibratethe relative Martian chronologypresently available from meteoriticcrater counting.

Description: No abstract available

Description: Landing space craft rocket plume exhaust interactions with the regolith surfaces on the Moon and Mars will result in cratering and regolith particle ejecta traveling at velocities up to 2,000 meters per second in the vacuum surroundings. This phenomenon creates hazards for the spacecraft that is landing or launching and may also cause damage to surrounding assets, personnel and infrastructure. One potential solution to this issue is to construct vertical takeoff and vertical landing (VTVL) pad infrastructure systems which will mitigate these rocket plume exhaust effects. Concepts will be presented for the construction and maintenance of such VTVL pads in lunar and martian environments.