ALBERT

Description: Bright carbonate deposits as evidence of aqueous alteration on (1) Ceres Nature 536, 7614 (2016). doi:10.1038/nature18290 Authors: M. C. De Sanctis, A. Raponi, E. Ammannito, M. Ciarniello, M. J. Toplis, H. Y. McSween, J. C. Castillo-Rogez, B. L. Ehlmann, F. G. Carrozzo, S. Marchi, F. Tosi, F. Zambon, F. Capaccioni, M. T. Capria, S. Fonte, M. Formisano, A. Frigeri, M. Giardino, A. Longobardo, G. Magni, E. Palomba, L. A. McFadden, C. M. Pieters, R. Jaumann, P. Schenk, R. Mugnuolo, C. A. Raymond & C. T. Russell The typically dark surface of the dwarf planet Ceres is punctuated by areas of much higher albedo, most prominently in the Occator crater. These small bright areas have been tentatively interpreted as containing a large amount of hydrated magnesium sulfate, in contrast to the average surface, which is a mixture of low-albedo materials and magnesium phyllosilicates, ammoniated phyllosilicates and carbonates. Here we report high spatial and spectral resolution near-infrared observations of the bright areas in the Occator crater on Ceres. Spectra of these bright areas are consistent with a large amount of sodium carbonate, constituting the most concentrated known extraterrestrial occurrence of carbonate on kilometre-wide scales in the Solar System. The carbonates are mixed with a dark component and small amounts of phyllosilicates, as well as ammonium carbonate or ammonium chloride. Some of these compounds have also been detected in the plume of Saturn’s sixth-largest moon Enceladus. The compounds are endogenous and we propose that they are the solid residue of crystallization of brines and entrained altered solids that reached the surface from below. The heat source may have been transient (triggered by impact heating). Alternatively, internal temperatures may be above the eutectic temperature of subsurface brines, in which case fluids may exist at depth on Ceres today.

Description: Executive Summary Return of samples from the surface of Mars has been a goal of the international Mars science community for many years. Affirmation by NASA and ESA of the importance of Mars exploration led the agencies to establish the international MSR Objectives and Samples Team (iMOST). The purpose of the team is to re‐evaluate and update the sample‐related science and engineering objectives of a Mars Sample Return (MSR) campaign. The iMOST team has also undertaken to define the measurements and the types of samples that can best address the objectives. Seven objectives have been defined for MSR, traceable through two decades of previously published international priorities. The first two objectives are further divided into sub‐objectives. Within the main part of the report, the importance to science and/or engineering of each objective is described, critical measurements that would address the objectives are specified, and the kinds of samples that would be most likely to carry key information are identified. These seven objectives provide a framework for demonstrating how the first set of returned Martian samples would impact future Martian science and exploration. They also have implications for how analogous investigations might be conducted for samples returned by future missions from other solar system bodies, especially those that may harbor biologically relevant or sensitive material, such as Ocean Worlds (Europa, Enceladus, Titan) and others. Summary of Objectives and Sub‐Objectives for MSR Identified by iMOST Objective 1 Interpret the primary geologic processes and history that formed the Martian geologic record, with an emphasis on the role of water. Intent To investigate the geologic environment(s) represented at the Mars 2020 landing site, provide definitive geologic context for collected samples, and detail any characteristics that might relate to past biologic processesThis objective is divided into five sub‐objectives that would apply at different landing sites. 1.1 Characterize the essential stratigraphic, sedimentologic, and facies variations of a sequence of Martian sedimentary rocks. Intent To understand the preserved Martian sedimentary record. Samples A suite of sedimentary rocks that span the range of variation. Importance Basic inputs into the history of water, climate change, and the possibility of life 1.2 Understand an ancient Martian hydrothermal system through study of its mineralization products and morphological expression. Intent To evaluate at least one potentially life‐bearing “habitable” environment Samples A suite of rocks formed and/or altered by hydrothermal fluids. Importance Identification of a potentially habitable geochemical environment with high preservation potential. 1.3 Understand the rocks and minerals representative of a deep subsurface groundwater environment. Intent To evaluate definitively the role of water in the subsurface. Samples Suites of rocks/veins representing water/rock interaction in the subsurface. Importance May constitute the longest‐lived habitable environments and a key to the hydrologic cycle. 1.4 Understand water/rock/atmosphere interactions at the Martian surface and how they have changed with time. Intent To constrain time‐variable factors necessary to preserve records of microbial life. Samples Regolith, paleosols, and evaporites. Importance Subaerial near‐surface processes could support and preserve microbial life. 1.5 Determine the petrogenesis of Martian igneous rocks in time and space. Intent To provide definitive characterization of igneous rocks on Mars. Samples Diverse suites of ancient igneous rocks. Importance Thermochemical record of the planet and nature of the interior. Objective 2 Assess and interpret the potential biological history of Mars, including assaying returned samples for the evidence of life. Intent To investigate the nature and extent of Martian habitability, the conditions and processes that supported or challenged life, how different environments might have influenced the preservation of biosignatures and created nonbiological “mimics,” and to look for biosignatures of past or present life.This objective has three sub‐objectives: 2.1 Assess and characterize carbon, including possible organic and pre‐biotic chemistry. Samples All samples collected as part of Objective 1. Importance Any biologic molecular scaffolding on Mars would likely be carbon‐based. 2.2 Assay for the presence of biosignatures of past life at sites that hosted habitable environments and could have preserved any biosignatures. Samples All samples collected as part of Objective 1. Importance Provides the means of discovering ancient life. 2.3 Assess the possibility that any life forms detected are alive, or were recently alive. Samples All samples collected as part of Objective 1. Importance Planetary protection, and arguably the most important scientific discovery possible. Objective 3 Quantitatively determine the evolutionary timeline of Mars. Intent To provide a radioisotope‐based time scale for major events, including magmatic, tectonic, fluvial, and impact events, and the formation of major sedimentary deposits and geomorphological features. Samples Ancient igneous rocks that bound critical stratigraphic intervals or correlate with crater‐dated surfaces. Importance Quantification of Martian geologic history. Objective 4 Constrain the inventory of Martian volatiles as a function of geologic time and determine the ways in which these volatiles have interacted with Mars as a geologic system. Intent To recognize and quantify the major roles that volatiles (in the atmosphere and in the hydrosphere) play in Martian geologic and possibly biologic evolution. Samples Current atmospheric gas, ancient atmospheric gas trapped in older rocks, and minerals that equilibrated with the ancient atmosphere. Importance Key to understanding climate and environmental evolution. Objective 5 Reconstruct the processes that have affected the origin and modification of the interior, including the crust, mantle, core and the evolution of the Martian dynamo. Intent To quantify processes that have shaped the planet's crust and underlying structure, including planetary differentiation, core segregation and state of the magnetic dynamo, and cratering. Samples Igneous, potentially magnetized rocks (both igneous and sedimentary) and impact‐generated samples. Importance Elucidate fundamental processes for comparative planetology. Objective 6 Understand and quantify the potential Martian environmental hazards to future human exploration and the terrestrial biosphere. Intent To define and mitigate an array of health risks related to the Martian environment associated with the potential future human exploration of Mars. Samples Fine‐grained dust and regolith samples. Importance Key input to planetary protection planning and astronaut health. Objective 7 Evaluate the type and distribution of in‐situ resources to support potential future Mars exploration. Intent To quantify the potential for obtaining Martian resources, including use of Martian materials as a source of water for human consumption, fuel production, building fabrication, and agriculture. Samples Regolith. Importance Production of simulants that will facilitate long‐term human presence on Mars. Summary of iMOST Findings Several specific findings were identified during the iMOST study. While they are not explicit recommendations, we suggest that they should serve as guidelines for future decision making regarding planning of potential future MSR missions. The samples to be collected by the Mars 2020 (M‐2020) rover will be of sufficient size and quality to address and solve a wide variety of scientific questions. Samples, by definition, are a statistical representation of a larger entity. Our ability to interpret the source geologic units and processes by studying sample sub sets is highly dependent on the quality of the sample context. In the case of the M‐2020 samples, the context is expected to be excellent, and at multiple scales. (A) Regional and planetary context will be established by the on‐going work of the multi‐agency fleet of Mars orbiters. (B) Local context will be established at field area‐ to outcrop‐ to hand sample‐ to hand lens scale using the instruments carried by M‐2020. A significant fraction of the value of the MSR sample collection would come from its organization into sample suites, which are small groupings of samples designed to represent key aspects of geologic or geochemical variation. If the Mars 2020 rover acquires a scientifically well‐chosen set of samples, with sufficient geological diversity, and if those samples were returned to Earth, then major progress can be expected on all seven of the objectives proposed in this study, regardless of the final choice of landing site. The specifics of which parts of Objective 1 could be achieved would be different at each of the final three candidate landing sites, but some combination of critically important progress could be made at any of them. An aspect of the search for evidence of life is that we do not know in advance how evidence for Martian life would be preserved in the geologic record.  In order for the returned samples to be most useful for both understanding geologic processes (Objective 1) and the search for life (Objective 2), the sample collection should contain BOTH typical and unusual samples from the rock units explored.  This consideration should be incorporated into sample selection and the design of the suites.  The retrieval missions of a MSR campaign should (1) minimize stray magnetic fields to which the samples would be exposed and carry a magnetic witness plate to record exposure, (2) collect and return atmospheric gas sample(s), and (3) collect additional dust and/or regolith sample mass if possible.

Description: Abstract Executive summary provided in lieu of abstract.

Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McSween, Harry Y -- England -- Nature. 2009 Mar 5;458(7234):45. doi: 10.1038/458045a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19262665" target="_blank"〉PubMed〈/a〉

Description: Studies of the dwarf planet (1) Ceres using ground-based and orbiting telescopes have concluded that its closest meteoritic analogues are the volatile-rich CI and CM carbonaceous chondrites. Water in clay minerals, ammoniated phyllosilicates, or a mixture of Mg(OH)2 (brucite), Mg2CO3 and iron-rich serpentine have all been proposed to exist on the surface. In particular, brucite has been suggested from analysis of the mid-infrared spectrum of Ceres. But the lack of spectral data across telluric absorption bands in the wavelength region 2.5 to 2.9 micrometres--where the OH stretching vibration and the H2O bending overtone are found--has precluded definitive identifications. In addition, water vapour around Ceres has recently been reported, possibly originating from localized sources. Here we report spectra of Ceres from 0.4 to 5 micrometres acquired at distances from ~82,000 to 4,300 kilometres from the surface. Our measurements indicate widespread ammoniated phyllosilicates across the surface, but no detectable water ice. Ammonia, accreted either as organic matter or as ice, may have reacted with phyllosilicates on Ceres during differentiation. This suggests that material from the outer Solar System was incorporated into Ceres, either during its formation at great heliocentric distance or by incorporation of material transported into the main asteroid belt.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉De Sanctis, M C -- Ammannito, E -- Raponi, A -- Marchi, S -- McCord, T B -- McSween, H Y -- Capaccioni, F -- Capria, M T -- Carrozzo, F G -- Ciarniello, M -- Longobardo, A -- Tosi, F -- Fonte, S -- Formisano, M -- Frigeri, A -- Giardino, M -- Magni, G -- Palomba, E -- Turrini, D -- Zambon, F -- Combe, J-P -- Feldman, W -- Jaumann, R -- McFadden, L A -- Pieters, C M -- Prettyman, T -- Toplis, M -- Raymond, C A -- Russell, C T -- England -- Nature. 2015 Dec 10;528(7581):241-4. doi: 10.1038/nature16172.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Istituto di Astrofisica e Planetologia Spaziali, INAF, Via del Fosso del Cavaliere 100, 00133 Roma, Italy. ; Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095-1567, USA. ; Southwest Research Institute, 1050 Walnut Street, Boulder, Colorado 80302, USA. ; Bear Fight Institute, 22 Fiddler's Road, PO Box 667, Winthrop, Washington 98862, USA. ; Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996-1410, USA. ; Planetary Science Institute, Tucson, Arizona 85719-2395, USA. ; Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany. ; NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA. ; Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, Rhode Island 02912, USA. ; Institut de Recherche d'Astrophysique et Planetologie, Observatoire Midi Pyrenees, Universite Paul Sabatier, 14 Avenue E. Belin, 31400 Toulouse, France. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26659184" target="_blank"〉PubMed〈/a〉

Description: Home Plate is a layered plateau in Gusev crater on Mars. It is composed of clastic rocks of moderately altered alkali basalt composition, enriched in some highly volatile elements. A coarsegrained lower unit lies under a finer-grained upper unit. Textural observations indicate that the lower strata were emplaced in an explosive event, and geochemical considerations favor an explosive volcanic origin over an impact origin. The lower unit likely represents accumulation of pyroclastic materials, whereas the upper unit may represent eolian reworking of the same pyroclastic materials.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Squyres, S W -- Aharonson, O -- Clark, B C -- Cohen, B A -- Crumpler, L -- de Souza, P A -- Farrand, W H -- Gellert, R -- Grant, J -- Grotzinger, J P -- Haldemann, A F C -- Johnson, J R -- Klingelhofer, G -- Lewis, K W -- Li, R -- McCoy, T -- McEwen, A S -- McSween, H Y -- Ming, D W -- Moore, J M -- Morris, R V -- Parker, T J -- Rice, J W Jr -- Ruff, S -- Schmidt, M -- Schroder, C -- Soderblom, L A -- Yen, A -- New York, N.Y. -- Science. 2007 May 4;316(5825):738-42.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17478719" target="_blank"〉PubMed〈/a〉

Description: The composition of Mars' crust records the planet's integrated geologic history and provides clues to its differentiation. Spacecraft and meteorite data now provide a global view of the chemistry of the igneous crust that can be used to assess this history. Surface rocks on Mars are dominantly tholeiitic basalts formed by extensive partial melting and are not highly weathered. Siliceous or calc-alkaline rocks produced by melting and/or fractional crystallization of hydrated, recycled mantle sources, and silica-poor rocks produced by limited melting of alkali-rich mantle sources, are uncommon or absent. Spacecraft data suggest that martian meteorites are not representative of older, more voluminous crust and prompt questions about their use in defining diagnostic geochemical characteristics and in constraining mantle compositional models for Mars.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McSween, Harry Y Jr -- Taylor, G Jeffrey -- Wyatt, Michael B -- New York, N.Y. -- Science. 2009 May 8;324(5928):736-9. doi: 10.1126/science.1165871.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Planetary Geosciences Institute and Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996-1410, USA. mcsween@utk.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19423810" target="_blank"〉PubMed〈/a〉

Description: Multispectral images (0.44 to 0.98 mum) of asteroid (4) Vesta obtained by the Dawn Framing Cameras reveal global color variations that uncover and help understand the north-south hemispherical dichotomy. The signature of deep lithologies excavated during the formation of the Rheasilvia basin on the south pole has been preserved on the surface. Color variations (band depth, spectral slope, and eucrite-diogenite abundance) clearly correlate with distinct compositional units. Vesta displays the greatest variation of geometric albedo (0.10 to 0.67) of any asteroid yet observed. Four distinct color units are recognized that chronicle processes--including impact excavation, mass wasting, and space weathering--that shaped the asteroid's surface. Vesta's color and photometric diversity are indicative of its status as a preserved, differentiated protoplanet.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reddy, Vishnu -- Nathues, Andreas -- Le Corre, Lucille -- Sierks, Holger -- Li, Jian-Yang -- Gaskell, Robert -- McCoy, Timothy -- Beck, Andrew W -- Schroder, Stefan E -- Pieters, Carle M -- Becker, Kris J -- Buratti, Bonnie J -- Denevi, Brett -- Blewett, David T -- Christensen, Ulrich -- Gaffey, Michael J -- Gutierrez-Marques, Pablo -- Hicks, Michael -- Keller, Horst Uwe -- Maue, Thorsten -- Mottola, Stefano -- McFadden, Lucy A -- McSween, Harry Y -- Mittlefehldt, David -- O'Brien, David P -- Raymond, Carol -- Russell, Christopher -- New York, N.Y. -- Science. 2012 May 11;336(6082):700-4. doi: 10.1126/science.1219088.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max Planck Institute for Solar System Research, Max-Planck-Strasse 2, 37191 Katlenburg-Lindau, Germany. reddy@mps.mpg.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22582258" target="_blank"〉PubMed〈/a〉

Description: Vesta's surface is characterized by abundant impact craters, some with preserved ejecta blankets, large troughs extending around the equatorial region, enigmatic dark material, and widespread mass wasting, but as yet an absence of volcanic features. Abundant steep slopes indicate that impact-generated surface regolith is underlain by bedrock. Dawn observations confirm the large impact basin (Rheasilvia) at Vesta's south pole and reveal evidence for an earlier, underlying large basin (Veneneia). Vesta's geology displays morphological features characteristic of the Moon and terrestrial planets as well as those of other asteroids, underscoring Vesta's unique role as a transitional solar system body.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jaumann, R -- Williams, D A -- Buczkowski, D L -- Yingst, R A -- Preusker, F -- Hiesinger, H -- Schmedemann, N -- Kneissl, T -- Vincent, J B -- Blewett, D T -- Buratti, B J -- Carsenty, U -- Denevi, B W -- De Sanctis, M C -- Garry, W B -- Keller, H U -- Kersten, E -- Krohn, K -- Li, J-Y -- Marchi, S -- Matz, K D -- McCord, T B -- McSween, H Y -- Mest, S C -- Mittlefehldt, D W -- Mottola, S -- Nathues, A -- Neukum, G -- O'Brien, D P -- Pieters, C M -- Prettyman, T H -- Raymond, C A -- Roatsch, T -- Russell, C T -- Schenk, P -- Schmidt, B E -- Scholten, F -- Stephan, K -- Sykes, M V -- Tricarico, P -- Wagner, R -- Zuber, M T -- Sierks, H -- New York, N.Y. -- Science. 2012 May 11;336(6082):687-90. doi: 10.1126/science.1219122.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉German Aerospace Center, Institute of Planetary Research, Berlin, Germany. ralf.jaumann@dlr.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22582254" target="_blank"〉PubMed〈/a〉

Description: Vesta is a large differentiated rocky body in the main asteroid belt that accreted within the first few million years after the formation of the earliest solar system solids. The Dawn spacecraft extensively imaged Vesta's surface, revealing a collision-dominated history. Results show that Vesta's cratering record has a strong north-south dichotomy. Vesta's northern heavily cratered terrains retain much of their earliest history. The southern hemisphere was reset, however, by two major collisions in more recent times. We estimate that the youngest of these impact structures, about 500 kilometers across, formed about 1 billion years ago, in agreement with estimates of Vesta asteroid family age based on dynamical and collisional constraints, supporting the notion that the Vesta asteroid family was formed during this event.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marchi, S -- McSween, H Y -- O'Brien, D P -- Schenk, P -- De Sanctis, M C -- Gaskell, R -- Jaumann, R -- Mottola, S -- Preusker, F -- Raymond, C A -- Roatsch, T -- Russell, C T -- New York, N.Y. -- Science. 2012 May 11;336(6082):690-4. doi: 10.1126/science.1218757.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉NASA Lunar Science Institute, Boulder, CO, USA. marchi@boulder.swri.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22582255" target="_blank"〉PubMed〈/a〉