ALBERT

Description: ABSTRACT As with most dune fields, the White Sands Dune Field in New Mexico forms in a wind regime that is not unimodal. In this study, crescentic dune shape change (deformation) with migration at White Sands was explored in a time series of five lidar-derived digital elevation models (DEM) and compared to a record of wind direction and speed during the same period. For the study period of June 2007 - June 2010, 244 sand-transporting wind events occurred and define a dominant wind mode from the SW and lesser modes from the NNW and SSE. Based upon difference maps and tracing of dune brinklines, overall dune behavior consists of crest-normal migration to the NE, but also along-crest migration of dune sinuosity and stoss superimposed dunes to the SE. The SW winds are transverse to dune orientations and cause most forward migration. The NNW winds cause along-crest migration of dune sinuosity and stoss bedforms, as well as SE migration of NE-trending dune terminations. The SSE winds cause ephemeral dune deformation, especially crestal slipface reversals. The dunes deform with migration because of differences in dune-segment size, and differences in the lee-face deposition rate as a function of the incidence angle between the wind direction and the local brinkline orientation. Each wind event deforms dune shape, this new shape then serves as the boundary condition for the next wind event. Shared incidence-angle control on dune deformation and lee-face stratification types allows for an idealized model for White Sands dunes. This article is protected by copyright. All rights reserved.

Description: Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and (18)O/(16)O in water and (13)C/(12)C, (18)O/(16)O, (17)O/(16)O, and (13)C(18)O/(12)C(16)O in carbon dioxide, made in the martian atmosphere at Gale Crater from the Curiosity rover using the Sample Analysis at Mars (SAM)'s tunable laser spectrometer (TLS). Comparison between our measurements in the modern atmosphere and those of martian meteorites such as ALH 84001 implies that the martian reservoirs of CO2 and H2O were largely established ~4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Webster, Chris R -- Mahaffy, Paul R -- Flesch, Gregory J -- Niles, Paul B -- Jones, John H -- Leshin, Laurie A -- Atreya, Sushil K -- Stern, Jennifer C -- Christensen, Lance E -- Owen, Tobias -- Franz, Heather -- Pepin, Robert O -- Steele, Andrew -- MSL Science Team -- Achilles, Cherie -- Agard, Christophe -- Alves Verdasca, Jose Alexandre -- Anderson, Robert -- Anderson, Ryan -- Archer, Doug -- Armiens-Aparicio, Carlos -- Arvidson, Ray -- Atlaskin, Evgeny -- Aubrey, Andrew -- Baker, Burt -- Baker, Michael -- Balic-Zunic, Tonci -- Baratoux, David -- Baroukh, Julien -- Barraclough, Bruce -- Bean, Keri -- Beegle, Luther -- Behar, Alberto -- Bell, James -- Bender, Steve -- Benna, Mehdi -- Bentz, Jennifer -- Berger, Gilles -- Berger, Jeff -- Berman, Daniel -- Bish, David -- Blake, David F -- Blanco Avalos, Juan J -- Blaney, Diana -- Blank, Jen -- Blau, Hannah -- Bleacher, Lora -- Boehm, Eckart -- Botta, Oliver -- Bottcher, Stephan -- Boucher, Thomas -- Bower, Hannah -- Boyd, Nick -- Boynton, Bill -- Breves, Elly -- Bridges, John -- Bridges, Nathan -- Brinckerhoff, William -- Brinza, David -- Bristow, Thomas -- Brunet, Claude -- Brunner, Anna -- Brunner, Will -- Buch, Arnaud -- Bullock, Mark -- Burmeister, Sonke -- Cabane, Michel -- Calef, Fred -- Cameron, James -- Campbell, John -- Cantor, Bruce -- Caplinger, Michael -- Caride Rodriguez, Javier -- Carmosino, Marco -- Carrasco Blazquez, Isaias -- Charpentier, Antoine -- Chipera, Steve -- Choi, David -- Clark, Benton -- Clegg, Sam -- Cleghorn, Timothy -- Cloutis, Ed -- Cody, George -- Coll, Patrice -- Conrad, Pamela -- Coscia, David -- Cousin, Agnes -- Cremers, David -- Crisp, Joy -- Cros, Alain -- Cucinotta, Frank -- d'Uston, Claude -- Davis, Scott -- Day, Mackenzie -- de la Torre Juarez, Manuel -- DeFlores, Lauren -- DeLapp, Dorothea -- DeMarines, Julia -- DesMarais, David -- Dietrich, William -- Dingler, Robert -- Donny, Christophe -- Downs, Bob -- Drake, Darrell -- Dromart, Gilles -- Dupont, Audrey -- Duston, Brian -- Dworkin, Jason -- Dyar, M Darby -- Edgar, Lauren -- Edgett, Kenneth -- Edwards, Christopher -- Edwards, Laurence -- Ehlmann, Bethany -- Ehresmann, Bent -- Eigenbrode, Jen -- Elliott, Beverley -- Elliott, Harvey -- Ewing, Ryan -- Fabre, Cecile -- Fairen, Alberto -- Farley, Ken -- Farmer, Jack -- Fassett, Caleb -- Favot, Laurent -- Fay, Donald -- Fedosov, Fedor -- Feldman, Jason -- Feldman, Sabrina -- Fisk, Marty -- Fitzgibbon, Mike -- Floyd, Melissa -- Fluckiger, Lorenzo -- Forni, Olivier -- Fraeman, Abby -- Francis, Raymond -- Francois, Pascaline -- Freissinet, Caroline -- French, Katherine Louise -- Frydenvang, Jens -- Gaboriaud, Alain -- Gailhanou, Marc -- Garvin, James -- Gasnault, Olivier -- Geffroy, Claude -- Gellert, Ralf -- Genzer, Maria -- Glavin, Daniel -- Godber, Austin -- Goesmann, Fred -- Goetz, Walter -- Golovin, Dmitry -- Gomez Gomez, Felipe -- Gomez-Elvira, Javier -- Gondet, Brigitte -- Gordon, Suzanne -- Gorevan, Stephen -- Grant, John -- Griffes, Jennifer -- Grinspoon, David -- Grotzinger, John -- Guillemot, Philippe -- Guo, Jingnan -- Gupta, Sanjeev -- Guzewich, Scott -- Haberle, Robert -- Halleaux, Douglas -- Hallet, Bernard -- Hamilton, Vicky -- Hardgrove, Craig -- Harker, David -- Harpold, Daniel -- Harri, Ari-Matti -- Harshman, Karl -- Hassler, Donald -- Haukka, Harri -- Hayes, Alex -- Herkenhoff, Ken -- Herrera, Paul -- Hettrich, Sebastian -- Heydari, Ezat -- Hipkin, Victoria -- Hoehler, Tori -- Hollingsworth, Jeff -- Hudgins, Judy -- Huntress, Wesley -- Hurowitz, Joel -- Hviid, Stubbe -- Iagnemma, Karl -- Indyk, Steve -- Israel, Guy -- Jackson, Ryan -- Jacob, Samantha -- Jakosky, Bruce -- Jensen, Elsa -- Jensen, Jaqueline Klovgaard -- Johnson, Jeffrey -- Johnson, Micah -- Johnstone, Steve -- Jones, Andrea -- Joseph, Jonathan -- Jun, Insoo -- Kah, Linda -- Kahanpaa, Henrik -- Kahre, Melinda -- Karpushkina, Natalya -- Kasprzak, Wayne -- Kauhanen, Janne -- Keely, Leslie -- Kemppinen, Osku -- Keymeulen, Didier -- Kim, Myung-Hee -- Kinch, Kjartan -- King, Penny -- Kirkland, Laurel -- Kocurek, Gary -- Koefoed, Asmus -- Kohler, Jan -- Kortmann, Onno -- Kozyrev, Alexander -- Krezoski, Jill -- Krysak, Daniel -- Kuzmin, Ruslan -- Lacour, Jean Luc -- Lafaille, Vivian -- Langevin, Yves -- Lanza, Nina -- Lasue, Jeremie -- Le Mouelic, Stephane -- Lee, Ella Mae -- Lee, Qiu-Mei -- Lees, David -- Lefavor, Matthew -- Lemmon, Mark -- Lepinette Malvitte, Alain -- Leveille, Richard -- Lewin-Carpintier, Eric -- Lewis, Kevin -- Li, Shuai -- Lipkaman, Leslie -- Little, Cynthia -- Litvak, Maxim -- Lorigny, Eric -- Lugmair, Guenter -- Lundberg, Angela -- Lyness, Eric -- Madsen, Morten -- Maki, Justin -- Malakhov, Alexey -- Malespin, Charles -- Malin, Michael -- Mangold, Nicolas -- Manhes, Gerard -- Manning, Heidi -- Marchand, Genevieve -- Marin Jimenez, Mercedes -- Martin Garcia, Cesar -- Martin, Dave -- Martin, Mildred -- Martinez-Frias, Jesus -- Martin-Soler, Javier -- Martin-Torres, F Javier -- Mauchien, Patrick -- Maurice, Sylvestre -- McAdam, Amy -- McCartney, Elaina -- McConnochie, Timothy -- McCullough, Emily -- McEwan, Ian -- McKay, Christopher -- McLennan, Scott -- McNair, Sean -- Melikechi, Noureddine -- Meslin, Pierre-Yves -- Meyer, Michael -- Mezzacappa, Alissa -- Miller, Hayden -- Miller, Kristen -- Milliken, Ralph -- Ming, Douglas -- Minitti, Michelle -- Mischna, Michael -- Mitrofanov, Igor -- Moersch, Jeff -- Mokrousov, Maxim -- Molina Jurado, Antonio -- Moores, John -- Mora-Sotomayor, Luis -- Morookian, John Michael -- Morris, Richard -- Morrison, Shaunna -- Mueller-Mellin, Reinhold -- Muller, Jan-Peter -- Munoz Caro, Guillermo -- Nachon, Marion -- Navarro Lopez, Sara -- Navarro-Gonzalez, Rafael -- Nealson, Kenneth -- Nefian, Ara -- Nelson, Tony -- Newcombe, Megan -- Newman, Claire -- Newsom, Horton -- Nikiforov, Sergey -- Nixon, Brian -- Noe Dobrea, Eldar -- Nolan, Thomas -- Oehler, Dorothy -- Ollila, Ann -- Olson, Timothy -- de Pablo Hernandez, Miguel Angel -- Paillet, Alexis -- Pallier, Etienne -- Palucis, Marisa -- Parker, Timothy -- Parot, Yann -- Patel, Kiran -- Paton, Mark -- Paulsen, Gale -- Pavlov, Alex -- Pavri, Betina -- Peinado-Gonzalez, Veronica -- Peret, Laurent -- Perez, Rene -- Perrett, Glynis -- Peterson, Joe -- Pilorget, Cedric -- Pinet, Patrick -- Pla-Garcia, Jorge -- Plante, Ianik -- Poitrasson, Franck -- Polkko, Jouni -- Popa, Radu -- Posiolova, Liliya -- Posner, Arik -- Pradler, Irina -- Prats, Benito -- Prokhorov, Vasily -- Purdy, Sharon Wilson -- Raaen, Eric -- Radziemski, Leon -- Rafkin, Scot -- Ramos, Miguel -- Rampe, Elizabeth -- Raulin, Francois -- Ravine, Michael -- Reitz, Gunther -- Renno, Nilton -- Rice, Melissa -- Richardson, Mark -- Robert, Francois -- Robertson, Kevin -- Rodriguez Manfredi, Jose Antonio -- Romeral-Planello, Julio J -- Rowland, Scott -- Rubin, David -- Saccoccio, Muriel -- Salamon, Andrew -- Sandoval, Jennifer -- Sanin, Anton -- Sans Fuentes, Sara Alejandra -- Saper, Lee -- Sarrazin, Philippe -- Sautter, Violaine -- Savijarvi, Hannu -- Schieber, Juergen -- Schmidt, Mariek -- Schmidt, Walter -- Scholes, Daniel -- Schoppers, Marcel -- Schroder, Susanne -- Schwenzer, Susanne -- Sebastian Martinez, Eduardo -- Sengstacken, Aaron -- Shterts, Ruslan -- Siebach, Kirsten -- Siili, Tero -- Simmonds, Jeff -- Sirven, Jean-Baptiste -- Slavney, Susie -- Sletten, Ronald -- Smith, Michael -- Sobron Sanchez, Pablo -- Spanovich, Nicole -- Spray, John -- Squyres, Steven -- Stack, Katie -- Stalport, Fabien -- Stein, Thomas -- Stewart, Noel -- Stipp, Susan Louise Svane -- Stoiber, Kevin -- Stolper, Ed -- Sucharski, Bob -- Sullivan, Rob -- Summons, Roger -- Sumner, Dawn -- Sun, Vivian -- Supulver, Kimberley -- Sutter, Brad -- Szopa, Cyril -- Tan, Florence -- Tate, Christopher -- Teinturier, Samuel -- ten Kate, Inge -- Thomas, Peter -- Thompson, Lucy -- Tokar, Robert -- Toplis, Mike -- Torres Redondo, Josefina -- Trainer, Melissa -- Treiman, Allan -- Tretyakov, Vladislav -- Urqui-O'Callaghan, Roser -- Van Beek, Jason -- Van Beek, Tessa -- VanBommel, Scott -- Vaniman, David -- Varenikov, Alexey -- Vasavada, Ashwin -- Vasconcelos, Paulo -- Vicenzi, Edward -- Vostrukhin, Andrey -- Voytek, Mary -- Wadhwa, Meenakshi -- Ward, Jennifer -- Weigle, Eddie -- Wellington, Danika -- Westall, Frances -- Wiens, Roger Craig -- Wilhelm, Mary Beth -- Williams, Amy -- Williams, Joshua -- Williams, Rebecca -- Williams, Richard B -- Wilson, Mike -- Wimmer-Schweingruber, Robert -- Wolff, Mike -- Wong, Mike -- Wray, James -- Wu, Megan -- Yana, Charles -- Yen, Albert -- Yingst, Aileen -- Zeitlin, Cary -- Zimdar, Robert -- Zorzano Mier, Maria-Paz -- New York, N.Y. -- Science. 2013 Jul 19;341(6143):260-3. doi: 10.1126/science.1237961.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. chris.r.webster@jpl.nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23869013" target="_blank"〉PubMed〈/a〉

Description: The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MERs) Spirit and Opportunity. The fraction of sand 〈150 micrometers in size contains ~55% crystalline material consistent with a basaltic heritage and ~45% x-ray amorphous material. The amorphous component of Rocknest is iron-rich and silicon-poor and is the host of the volatiles (water, oxygen, sulfur dioxide, carbon dioxide, and chlorine) detected by the Sample Analysis at Mars instrument and of the fine-grained nanophase oxide component first described from basaltic soils analyzed by MERs. The similarity between soils and aeolian materials analyzed at Gusev Crater, Meridiani Planum, and Gale Crater implies locally sourced, globally similar basaltic materials or globally and regionally sourced basaltic components deposited locally at all three locations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Blake, D F -- Morris, R V -- Kocurek, G -- Morrison, S M -- Downs, R T -- Bish, D -- Ming, D W -- Edgett, K S -- Rubin, D -- Goetz, W -- Madsen, M B -- Sullivan, R -- Gellert, R -- Campbell, I -- Treiman, A H -- McLennan, S M -- Yen, A S -- Grotzinger, J -- Vaniman, D T -- Chipera, S J -- Achilles, C N -- Rampe, E B -- Sumner, D -- Meslin, P-Y -- Maurice, S -- Forni, O -- Gasnault, O -- Fisk, M -- Schmidt, M -- Mahaffy, P -- Leshin, L A -- Glavin, D -- Steele, A -- Freissinet, C -- Navarro-Gonzalez, R -- Yingst, R A -- Kah, L C -- Bridges, N -- Lewis, K W -- Bristow, T F -- Farmer, J D -- Crisp, J A -- Stolper, E M -- Des Marais, D J -- Sarrazin, P -- MSL Science Team -- New York, N.Y. -- Science. 2013 Sep 27;341(6153):1239505. doi: 10.1126/science.1239505.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Aeronautics and Space Administration Ames Research Center, Moffett Field, CA 94035, USA. david.blake@nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24072928" target="_blank"〉PubMed〈/a〉

Description: The Curiosity rover discovered fine-grained sedimentary rocks, which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. Carbon, hydrogen, oxygen, sulfur, nitrogen, and phosphorus were measured directly as key biogenic elements; by inference, phosphorus is assumed to have been available. The environment probably had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grotzinger, J P -- Sumner, D Y -- Kah, L C -- Stack, K -- Gupta, S -- Edgar, L -- Rubin, D -- Lewis, K -- Schieber, J -- Mangold, N -- Milliken, R -- Conrad, P G -- DesMarais, D -- Farmer, J -- Siebach, K -- Calef, F 3rd -- Hurowitz, J -- McLennan, S M -- Ming, D -- Vaniman, D -- Crisp, J -- Vasavada, A -- Edgett, K S -- Malin, M -- Blake, D -- Gellert, R -- Mahaffy, P -- Wiens, R C -- Maurice, S -- Grant, J A -- Wilson, S -- Anderson, R C -- Beegle, L -- Arvidson, R -- Hallet, B -- Sletten, R S -- Rice, M -- Bell, J 3rd -- Griffes, J -- Ehlmann, B -- Anderson, R B -- Bristow, T F -- Dietrich, W E -- Dromart, G -- Eigenbrode, J -- Fraeman, A -- Hardgrove, C -- Herkenhoff, K -- Jandura, L -- Kocurek, G -- Lee, S -- Leshin, L A -- Leveille, R -- Limonadi, D -- Maki, J -- McCloskey, S -- Meyer, M -- Minitti, M -- Newsom, H -- Oehler, D -- Okon, A -- Palucis, M -- Parker, T -- Rowland, S -- Schmidt, M -- Squyres, S -- Steele, A -- Stolper, E -- Summons, R -- Treiman, A -- Williams, R -- Yingst, A -- MSL Science Team -- New York, N.Y. -- Science. 2014 Jan 24;343(6169):1242777. doi: 10.1126/science.1242777. Epub 2013 Dec 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Geologic and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24324272" target="_blank"〉PubMed〈/a〉

Description: Crater basins on Mars host thick sedimentary sequences, which record the environments of early Mars. These basin fills commonly exhibit mound morphologies thought to arise from aeolian erosion of initially crater filling strata. This study presents transport-based models explaining how mounds could be carved by wind. Wind tunnel experiments generated morphologies similar to those observed on Mars, and numerical modeling of flow over a crater using large-eddy simulation (LES) demonstrated a positive feedback between topographic focusing of flow and erosion potential. Observations of yardangs, dunes, and wind streaks, all proxies for wind direction, largely agree with model results. Where mound strata origins have been interpreted, basal subaqueous deposits are overlain by aeolian deposits. This stratigraphic progression, culminating in wind-driven excavation, is consistent with a global desiccation event. The occurrence of sedimentary mounds only on Noachian terrain argues that this event was related to late Noachian climatic change.

Description: The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grotzinger, J P -- Gupta, S -- Malin, M C -- Rubin, D M -- Schieber, J -- Siebach, K -- Sumner, D Y -- Stack, K M -- Vasavada, A R -- Arvidson, R E -- Calef, F 3rd -- Edgar, L -- Fischer, W F -- Grant, J A -- Griffes, J -- Kah, L C -- Lamb, M P -- Lewis, K W -- Mangold, N -- Minitti, M E -- Palucis, M -- Rice, M -- Williams, R M E -- Yingst, R A -- Blake, D -- Blaney, D -- Conrad, P -- Crisp, J -- Dietrich, W E -- Dromart, G -- Edgett, K S -- Ewing, R C -- Gellert, R -- Hurowitz, J A -- Kocurek, G -- Mahaffy, P -- McBride, M J -- McLennan, S M -- Mischna, M -- Ming, D -- Milliken, R -- Newsom, H -- Oehler, D -- Parker, T J -- Vaniman, D -- Wiens, R C -- Wilson, S A -- New York, N.Y. -- Science. 2015 Oct 9;350(6257):aac7575. doi: 10.1126/science.aac7575.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Geologic and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. ; Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK. ; Malin Space Science Systems, Post Office Box 910148, San Diego, CA 92121, USA. ; Department of Earth and Planetary Sciences, University of California-Santa Cruz, Santa Cruz, CA 95064, USA. ; Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA. ; Department of Earth and Planetary Sciences, University of California-Davis, Davis, CA 95616, USA. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. ; Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA. ; Astrogeology Science Center, U.S. Geological Survey, Flagstaff, AZ 86001, USA. ; Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington, DC 20560, USA. ; Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996, USA. ; Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA. ; Laboratoire Planetologie et Geodynamique de Nantes-Le Centre National de la Recherche, Unite Mixte de Recherche 6112 and Universite de Nantes, 44322 Nantes, France. ; Planetary Science Institute, Tucson, AZ 85719, USA. ; Department of Geology, Western Washington University, Bellingham, WA 98225, USA. ; Department of Space Sciences, NASA Ames Research Center, Moffett Field, CA 94035, USA. ; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. ; Department of Earth and Planetary Science, University of California-Berkeley, Berkeley, CA 94720, USA. ; Laboratoire de Geologie de Lyon, Universite de Lyon, 69364 Lyon, France. ; Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA. ; Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada. ; Department of Geosciences, Stony Brook University, Stony Brook, NY 11794-2100, USA. ; Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712, USA. ; Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, TX 77058, USA. ; Department of Geological Sciences, Brown University, Providence, RI 02912, USA. ; Institute of Meteoritics, University of New Mexico, Albuquerque, NM 87131 USA. ; LZ Technology, NASA Johnson Space Center, Houston, TX 77058, USA. ; Space Remote Sensing, Los Alamos National Laboratory, Los Alamos, NM 87544, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26450214" target="_blank"〉PubMed〈/a〉

Description: [1]  During Sols 57-100, the Mars Science Laboratory Curiosity rover acquired and processed a solid (sediment) sample and analyzed its mineralogy and geochemistry with the Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM) instruments. An aeolian deposit —herein referred to as the Rocknest sand shadow—was inferred to represent a global average soil composition and selected for study to facilitate integration of analytical results with observations from earlier missions. During first-time activities, the Mars Hand Lens Imager (MAHLI) was used to support both science and engineering activities related to sample assessment, collection, and delivery. Here we report on MAHLI activities that directly supported sample analysis, and provide MAHLI observations regarding the grain-scale characteristics of the Rocknest sand shadow. MAHLI imaging confirms that the Rocknest sand shadow is one of a family of bimodal aeolian accumulations on Mars—similar to the coarse-grained ripples interrogated by the Mars Exploration Rovers Spirit and Opportunity —in which a surface veneer of coarse-grained sediment stabilizes predominantly fine-grained sediment of the deposit interior. The similarity in grain size distribution of these geographically disparate deposits support the widespread occurrence of bimodal aeolian transport on Mars. We suggest that preservation of bimodal aeolian deposits may be characteristic of regions of active deflation, where winnowing of the fine-sediment fraction results in a relatively low sediment load, and a preferential increase in the coarse-grained fraction of the sediment load. The compositional similarity of Martian aeolian deposits supports the potential for global redistribution of fine-grained components, combined with potential local contributions.