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  • Lunar and Planetary Science and Exploration  (10)
  • Humans
  • Life and Medical Sciences
  • ASTROPHYSICS
  • 2020-2021  (10)
  • 1
    Publication Date: 2020-03-26
    Description: Mariner 10 provided our first closeup reconnaissance of Mercury during its three flybys in 1974 and 1975. MESSENGERs 20112015 orbital investigation enabled numerous discoveries, several of which led to substantial or complete changes in our fundamental understanding of the planet. Among these were the unanticipated, widespread presence of volatile elements (e.g., Na, K, S); a surface with extremely low Fe abundance whose darkening agent is likely C; a previously unknown landformhollows that may form by volatile sublimation from within rocks exposed to the harsh conditions on the surface; a history of expansive effusive and explosive volcanism; substantial radial contraction of the planet from interior cooling; offset of the dipole moment of the internal magnetic field northward from the geographic equator by ~20% of the planets radius; crustal magnetization, attributed at least in part to an ancient field; unexpected seasonal variability and relationships among exospheric species and processes; and the presence in permanently shadowed polar terrain of water ice and other volatile materials, likely to include complex organic compounds. Mercurys highly chemically reduced and unexpectedly volatile-rich composition is unique among the terrestrial planets and was not predicted by earlier hypotheses for the planets origin. As an end-member of terrestrial planet formation, Mercury holds unique clues about the original distribution of elements in the earliest stages of the Solar System and how planets (and exoplanets) form and evolve in close proximity to their host stars. The BepiColombo mission promises to expand our knowledge of this planet and to shed light on some of the mysteries revealed by the MESSENGER mission. However, several fundamental science questions raised by MESSENGERs pioneering exploration of Mercury can only be answered with in situ measurements from the planets surface.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN77065 , Lunar and Planetary Science Conference (LPSC); Mar 16, 2020 - Mar 20, 2020; The Woodlands, TX; United States
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  • 2
    Publication Date: 2020-03-26
    Description: The data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft have revealed several surprising characteristics about the surface of Mercury, leading to its classification as a geochemical endmember among the terrestrial planets. Some of these features include elevated abundances of up to 3 wt% S, C enrichment as high as 4 wt% over the local mean in low reflectance materials (LRM), Na up to 5 wt% at high northern latitudes, and Fe abundances typically lower than 2 wt% [e.g., 14]. The S and Fe concentrations have been used to infer that Mercurys igneous history evolved under highly reduced oxygen fugacity conditions between 2.6 and 7.3 log10 units below the iron-wstite buffer [e.g., 5], which is more reducing than any other terrestrial planet in the solar system [e.g., 6]. This highly reduced nature has important consequences for the differentiation and thermal/magmatic evolution of Mercury. While the immense amount of data collected by MESSENGER revealed Mercury as a geochemical endmember, this new knowledge gained raised additional questions that necessitate continued exploration of the planet. Fortunately, BepiColombo launched in October of 2018, and this joint ESA/JAXA dual-orbiter spacecraft is the most ambitious effort yet attempted to explore Mercury [e.g., 7]. Looking beyond BepiColombo, there are major aspects of Mercurys geochemical character and evolution for which significant knowledge gaps can be dramatically improved with data acquired from the planets surface via in situ landed science.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN77061 , Lunar and Planetary Science Conference; Mar 16, 2020 - Mar 20, 2020; The Woodlands, TX; United States
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  • 3
    Publication Date: 2020-03-28
    Description: The goal of the Apollo Next Generation Sample Analysis (ANGSA) Program is to study specially curated samples, that is, unstudied Apollo samples that have been preserved under unique conditions. A subset of the funded ANGSA work includes the study of Apollo samples stored under cold conditions since their return from the Moon. Ongoing ANGSA processing and future returned samples require cold curation strategies to preserve the integrity of organic and other temperature-sensitive constituents within those samples. Standard Apollo curation processing hardware and procedures are designed for room temperature operations, not cold conditions. This abstract details the major modifications of a heritage lunar cabinet in preparation for the first cold curation processing at Johnson Space Center. Future publications will provide greater detail on the low temperature materials and operation procedures. This work not only supports Apollo but also future cold sample return missions.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN77482 , Lunar Planetary Science Conference; Mar 16, 2020 - Mar 20, 2020; The Woodlands, TX; United States
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  • 4
    Publication Date: 2020-03-25
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN77282 , Human Research Program Investigators’ Workshop (HRP IWS 2020); Jan 27, 2020 - Jan 30, 2020; Galveston, TX; United States
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  • 5
    Publication Date: 2020-04-08
    Description: A driving factor for sending the Mars Science Laboratory, Curiosity rover to Gale Crater was the orbital detection of clay minerals in the Glen Torridon (GT) clay unit. Clay mineral detections in GT suggested a past aqueous environment that was habitable, and could contain organic evidence of past microbiology. The mission of the Sample Analysis at Mars (SAM) instrument onboard Curiosity was to detect organic evidence of past microbiology and to detect volatile bearing mineralogy that can inform on whether past geochemical conditions would have supported microbiological activity. The objective of this work was to 1) evaluate the depositional/alteration conditions of Blunts Point (BP) to GT sediments 2) search for evidence of organics, and 3) evaluate microbial habitability in the BP, Vera Rubin Ridge (VRR), and GT sedimentary rock.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN78912 , Lunar and Planetary Science Conference (LPSC); Mar 16, 2020 - Mar 20, 2020; The Woodlands, TX; United States
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  • 6
    Publication Date: 2020-03-28
    Description: The Genesis Discovery Mission passively allowed solar wind (SW) to implant into substrates during exposure times up to ~853 days from 2001 to 2004. The spacecraft then returned the SW to Earth for analysis. Substrates included semiconductor wafers (silicon, sapphire, and germanium), as well as a number of thin films supported by either silicon or sapphire wafers. During flight, subsets of the SW collectors were exposed to one of 4 SW regimes: bulk solar wind, coronal hole solar wind (CH, high speed), interstream solar wind (IS, low speed) or coronal mass ejections (CMEs). Each SW regime had a different composition and range of ion speeds and, during their collection, uniquely changed their host SW collector. This study focuses on bulk vs IS SW effects on CZ silicon.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN77490 , Lunar and Planetary Science Conference; Mar 18, 2020
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  • 7
    Publication Date: 2020-03-28
    Description: The Dawn mission revolutionized our understanding of Ceres during the same decade that has also witnessed the rise of ocean worlds as a research and exploration focus. We will report progress on the Planetary Mission Concept Study (PMCS) on the future exploration of Ceres under the New Frontiers or Flagship program that was selected for NASA funding in October 2019. At the time this writing, the study was just kicked off, hence this abstract reports the study plan as presented in the proposal.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN77179 , Lunar Planetary Science Conference (LPSC); Mar 16, 2020 - Mar 20, 2020; The Woodlands, TX; United States
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  • 8
    Publication Date: 2020-03-28
    Description: The Mars Science Laboratory (MSL) rover, Curiosity, has been traversing across fluvial, lacustrine, and eolian sedimentary rocks since it touched down in 2012. The CheMin X-ray diffractometer (XRD) on board Curiosity has revealed smectite clay minerals in most fluvio-lacustrine samples and abundant X-ray amorphous materials in all samples analyzed to date. For example, mudstones from the Sheepbed member at the base of the stratigraphic section and the lower part of the Murray formation contain on average ~7 to 20 wt% smectite and ~30 to 46 wt% X-ray amorphous abundances. On Earth, smectite and secondary X-ray amorphous materials are juvenile weathering products that are generated in sedimentary environments and ultimately record the interaction between primary igneous minerals and the hydrosphere, atmosphere, and biosphere. For this study, we investigated glacio-fluvio-eolian sediments generated in basaltic terrains as terrestrial analogs for the mudstones from Gale Crater, Mars. This work focuses on the clay sized sediments (〈2 m) from these deposits as this grain size hosts the most mineralogically and geochemically altered detritus in sedimentary environments. The goal of investigating basaltic sedimentation is to create a terrestrial reference frame that sheds light on the paleoclimate and paleoaqueous conditions responsible for shaping the ancient sedimentary environments of Mars (e.g., Gale Crater and Jezero Crater).
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN78283 , JSC-E-DAA-TN77066 , Lunar and Planetary Science Conference (LPSC); Mar 16, 2020 - Mar 20, 2020; The Woodlands, TX; United States
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  • 9
    Publication Date: 2020-04-08
    Description: The surfaces of airless bodies such as Mercury are continually modified by space weathering, which is driven by micrometeoroid impacts and solar wind irradiation. Space weathering alters the chemical composition, microstructure, and spectral properties of surface regolith. In lunar and ordinarychondritic style space weathering, these processes affect the reflectance properties by darkening (lowering of reflectance), reddening (increasing reflectance with increasing wavelength), and attenuation of characteristic absorption features. These optical changes are driven by the production of nanophase Febearing particles (npFe). While our understanding of these alteration processes has largely been based on data from the Moon and near-Earth S-type asteroids, the space weathering environment at Mercury is much more extreme. The surface of Mercury experiences a more intense solar wind flux and higher velocity micrometeoroid impacts than its planetary counterparts at 1 AU. Additionally, the composition of Mercurys surface varies significantly from that of the Moon. Most notably, a very low albedo unit has been identified on Mercurys surface, known as the low reflectance material (LRM). This unit is enriched with up to 4 wt.% carbon, likely in the form of graphite, over the local mean. In addition, the surface concentration of Fe across Mercurys surface is low (〈2 wt.%) compared to the Moon. Our understanding of how these low-Fe and carbon phases are altered as a result of space weathering processes is limited. Since Fe plays a critical role in the development of space weathering features on other airless surfaces (e.g., npFe), its limited availability on Mercury may strongly affect the space weathering features in surface materials. In order to understand how space weathering affects the chemical, microstructural, and optical properties of the surface of Mercury, we can simulate these processes in the laboratory [7]. Here we used pulsed laser irradiation to simulate the short duration, high temperature events associated with micrometeoroid impacts. We used forsteritic olivine, likely present on the Mercurian surface, with varying FeO contents, each mixed with graphite, in our experiments. We then performed reflectance spectroscopy and electron microscopy to investigate the spectral, chemical, and microstructural changes in these samples.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN78926 , Lunar and Planetary Science Conference (LPSC); Mar 16, 2020 - Mar 20, 2020; The Woodlands, TX; United States
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  • 10
    Publication Date: 2020-04-17
    Description: Chromatographic analysis of the Cumberland mudstone in Gale crater by the Sample Analysis at Mars (SAM) instrument revealed the detection of two to three isomers of dichlorobenzene. Their individual concentrations were estimated to be in the 0.517 ppbw range relative to the sample mass. We also report the first detection of trichloromethylpropane and the confirmation of the detection of chlorobenzene previously reported. Supporting laboratory experiments excluded the SAM internal background as the source of those compounds, thus confirming the organic carbon and chlorine of the newly detected chlorohydrocarbons are indigenous to the mudstone sample. Laboratory experiments also demonstrated that the chlorohydrocarbons were mainly produced from chemical reactions occurring in the SAM ovens between organic molecules and oxychlorines contained in the sample. The results we obtained show that meteoritic organics and tested chemical species (a polycyclic aromatic hydrocarbon, an amino acid, and a carboxylic acid) were plausible organic precursors of the chlorinated aromatic molecules detected with SAM, thus suggesting that they could be among the organic molecules present in the mudstone. Results from this study coupled with previously reported detections of chlorinated aromatics (〈300 ppbw) indigenous to the same mudstone highlight that organics can be preserved from the harsh surface conditions even at shallow depth. The detection of new chlorohydrocarbons with SAM confirms that organic molecules should have been available in an environment favorable to life forms, strengthening the habitability aspect of Gale crater. Key Words: MarsChlorinated organic moleculesIn situ measurementsSample Analysis at Mars MudstoneGale crater. Astrobiology 20, 292306.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN78323 , Astrobiology (ISSN 1531-1074) (e-ISSN 1557-8070); 20; 2; 292–306
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