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Jawin ER, Campbell BA, Whitten JL, Morgan GA. The Lateral Continuity and Vertical Arrangement of Dust Layers in the Martian North Polar Cap From SHARAD Multiband Data. GEOPHYSICAL RESEARCH LETTERS 2022; 49:e2022GL099896. [PMID: 36245892 PMCID: PMC9542121 DOI: 10.1029/2022gl099896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 08/15/2022] [Accepted: 08/19/2022] [Indexed: 06/16/2023]
Abstract
Interpretation of radar sounder reflections to infer the structure and composition of the martian polar caps depends on whether bright returns correspond to single packed dust layers or a more finely layered structure. Reflections from multiple layers can create strong resonant scattering (interference) effects that impact analyses of radargram reflectors and inference of dielectric contrast. We identify resonant behavior for an areally extensive reflector in the north polar layered deposits from Shallow Radar data processed in two frequency bands. Echo strength varies by ∼2 dB between subband reflections across a region ∼400 km in extent, with the stronger echo shifting abruptly from the high- to low-frequency band outside the central region of Gemina Lingula. This behavior can arise from resonant scattering between two layers of dust (0.3-0.6 m thick) separated by 0.5-3 m of ice. Such layering requires there be little postdepositional aeolian activity to preserve layer thickness and spacing.
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Affiliation(s)
- Erica R. Jawin
- Smithsonian InstitutionNational Air and Space MuseumWashingtonDCUSA
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2
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Ojha L, Buffo J, Karunatillake S, Siegler M. Groundwater production from geothermal heating on early Mars and implication for early martian habitability. SCIENCE ADVANCES 2020; 6:6/49/eabb1669. [PMID: 33268366 PMCID: PMC7710363 DOI: 10.1126/sciadv.abb1669] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 10/19/2020] [Indexed: 06/12/2023]
Abstract
In explaining extensive evidence for past liquid water, the debate on whether Mars was primarily warm and wet or cold and arid 4 billion years (Ga) ago has continued for decades. The Sun's luminosity was ~30% lower 4 Ga ago; thus, most martian climate models struggle to elevate the mean surface temperature past the melting point of water. Basal melting of ice sheets may help resolve that paradox. We modeled the thermophysical evolution of ice and estimate the geothermal heat flux required to produce meltwater on a cold, arid Mars. We then analyzed geophysical and geochemical data, showing that basal melting would have been feasible on Mars 4 Ga ago. If Mars were warm and wet 4 Ga ago, then the geothermal flux would have even sustained hydrothermal activity. Regardless of the actual nature of the ancient martian climate, the subsurface would have been the most habitable region on Mars.
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Affiliation(s)
- Lujendra Ojha
- Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
| | - Jacob Buffo
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
| | - Suniti Karunatillake
- Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70802, USA
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Frigeri A, Ercoli M. The ScanMars Subsurface Radar Sounding Experiment on AMADEE-18. ASTROBIOLOGY 2020; 20:1338-1352. [PMID: 33179967 DOI: 10.1089/ast.2019.2037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Terrestrial simulations for crewed missions are critically important for testing technologies and improving methods and procedures for future robotic and human planetary exploration. In February 2018, AMADEE-18 simulated a mission to Mars in the Dhofar region of Oman. During the mission, a field crew coordinated by the Österreichisches Weltraum Forum (OeWF) accomplished several experiments in the fields of astrobiology, space physiology and medicine, geology, and geophysics. Within the scientific payload of AMADEE-18, ScanMars provided geophysical radar imaging of the subsurface at the simulated landing site and was operated by analog astronauts wearing spacesuits during extra-vehicular activities. The analog astronauts were trained to operate a ground-penetrating radar instrument that transmits and then collects radio waves carrying information about the geological setting of the first few meters of the subsurface. The data presented in this work show signal returns from structures down to 4 m depth, associated with the geology of the investigated rocks. Integrating radar data and the analog astronauts' observations of the geology at the surface, it was possible to identify the contact between shallow sediments and bedrock, the local occurrence of conductive soils, and the presence of pebbly materials in the shallow subsurface, which together describe the geology of recent loose sediments overlying an older deformed bedrock. The results obtained by ScanMars confirm that subsurface radar sounding at martian landing sites is key for the geological characterization at shallow depths. The geologic model of the subsurface can be used as the basis for reconstructing palaeoenvironments and paleo-habitats, thus assisting scientific investigations looking for traces of present or past life on the Red Planet. Highlights The ScanMars experiment brings a ground-penetrating radar to the AMADEE-18 simulated Mars mission. The ScanMars radar was operated following procedures and training developed before the mission. Approximately 2000 m of radar data profiles have been acquired during the analog mission. Combining the results for ScanMars, orbital remote sensing data, and first-person observation in the field while wearing spacesuits (analog astronauts), it was possible to generate a geological model at the AMADEE-18 study site.
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Affiliation(s)
- Alessandro Frigeri
- Istituto di Astrofisica e Planetologia Spaziali (IAPS), Istituto Nazionale di Astrofisica (INAF), Rome, Italy
| | - Maurizio Ercoli
- Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, Perugia, Italy
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Putzig NE, Smith IB, Perry MR, Foss FJ, Campbell BA, Phillips RJ, Seu R. Three-dimensional radar imaging of structures and craters in the Martian polar caps. ICARUS 2018; 308:138-147. [PMID: 29749975 PMCID: PMC5937288 DOI: 10.1016/j.icarus.2017.09.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Over the last decade, observations acquired by the Shallow Radar (SHARAD) sounder on individual passes of the Mars Reconnaissance Orbiter have revealed the internal structure of the Martian polar caps and provided new insights into the formation of the icy layers within and their relationship to climate. However, a complete picture of the cap interiors has been hampered by interfering reflections from off-nadir surface features and signal losses associated with sloping structures and scattering. Foss et al. (2017) addressed these limitations by assembling three-dimensional data volumes of SHARAD observations from thousands of orbital passes over each polar region and applying geometric corrections simultaneously. The radar volumes provide unprecedented views of subsurface features, readily imaging structures previously inferred from time-intensive manual analysis of single-orbit data (e.g., trough-bounding surfaces, a buried chasma, and a basal unit in the north, massive carbon-dioxide ice deposits and discontinuous layered sequences in the south). Our new mapping of the carbon-dioxide deposits yields a volume of 16,500 km3, 11% larger than the prior estimate. In addition, the radar volumes newly reveal other structures, including what appear to be buried impact craters with no surface expression. Our first assessment of 21 apparent craters at the base of the north polar layered deposits suggests a Hesperian age for the substrate, consistent with that of the surrounding plains as determined from statistics of surface cratering rates. Planned mapping of similar features throughout both polar volumes may provide new constraints on the age of the icy layered deposits. The radar volumes also provide new topographic data between the highest latitudes observed by the Mars Orbiter Laser Altimeter and those observed by SHARAD. In general, mapping of features in these radar volumes is placing new constraints on the nature and evolution of the polar deposits and associated climate changes.
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Affiliation(s)
- Nathaniel E Putzig
- Planetary Science Institute, 1546 Cole Boulevard, Suite 120, Lakewood, CO 80401, USA
| | - Isaac B Smith
- Planetary Science Institute, 1546 Cole Boulevard, Suite 120, Lakewood, CO 80401, USA
| | - Matthew R Perry
- Planetary Science Institute, 1546 Cole Boulevard, Suite 120, Lakewood, CO 80401, USA
| | - Frederick J Foss
- Freestyle Analytical and Quantitative Services, LLC, 2210 Parkview Drive, Longmont, CO 80504, USA
| | - Bruce A Campbell
- Smithsonian Institution, MRC 315, Center for Earth and Planetary Studies, National Air and Space Museum, 4th and Independence Ave, SW, Washington, DC 20560, USA
| | - Roger J Phillips
- Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, MO 63130, USA
| | - Roberto Seu
- Sapienza University of Rome, DIET Department, Via Eudossiana, 18, 00184 Rome, ITALY
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Foss FJ, Putzig NE, Campbell BA, Phillips RJ. 3-D Imaging of Mars' Polar Ice Caps Using Orbital Radar Data. ACTA ACUST UNITED AC 2018; 36:43-57. [PMID: 29400351 DOI: 10.1190/tle36010043.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Since its arrival in early 2006, various instruments aboard NASA's Mars Reconnaissance Orbiter (MRO) have been collecting a variety of scientific and engineering data from orbit around Mars. Among these is the SHAllow RADar (SHARAD) instrument, supplied by Agenzia Spaziale Italiana (ASI) and designed for subsurface sounding in the 15-25 MHz frequency band. As of this writing, MRO has completed over 46,000 nearly polar orbits of Mars, 30% of which have included active SHARAD data collection. By 2009, a sufficient density of SHARAD coverage had been obtained over the polar regions to support 3-D processing and analysis of the data. Using tools and techniques commonly employed in terrestrial seismic data processing, we have processed subsets of the resulting collection of SHARAD observations covering the north and south polar regions as SHARAD 3-D volumes, imaging the interiors of the north and south polar ice caps known, respectively, as Planum Boreum and Planum Australe. After overcoming a series of challenges revealed during the 3-D processing and analysis, a completed Planum Boreum 3-D volume is currently being used for scientific research. Lessons learned in the northern work fed forward into our 3-D processing and analysis of the Planum Australe 3-D volume, currently under way. We discuss our experiences with these projects and present results and scientific insights stemming from these efforts.
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Affiliation(s)
- Frederick J Foss
- Freestyle Analytical & Quantitative Services, LLC, 2210 Parkview Drive, Longmont, CO 80504
| | - Nathaniel E Putzig
- Planetary Science Institute, 1546 Cole Blvd, Suite 120, Lakewood, CO 80401
| | - Bruce A Campbell
- Smithsonian Institution, MRC 315, PO Box 37012, Washington, DC 20013-7012
| | - Roger J Phillips
- Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, Campus Box 1169, One Brookings Drive, St. Louis, MO 63130-4899
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Abstract
Until the acquisition of in-situ measurements, the study of the present-day heat flow of Mars must rely on indirect methods, mainly based on the relation between the thermal state of the lithosphere and its mechanical strength, or on theoretical models of internal evolution. Here, we present a first-order global model for the present-day surface heat flow for Mars, based on the radiogenic heat production of the crust and mantle, on scaling of heat flow variations arising from crustal thickness and topography variations, and on the heat flow derived from the effective elastic thickness of the lithosphere beneath the North Polar Region. Our preferred model finds heat flows varying between 14 and 25 mW m-2, with an average value of 19 mW m-2. Similar results (although about ten percent higher) are obtained if we use heat flow based on the lithospheric strength of the South Polar Region. Moreover, expressing our results in terms of the Urey ratio (the ratio between total internal heat production and total heat loss through the surface), we estimate values close to 0.7-0.75, which indicates a moderate contribution of secular cooling to the heat flow of Mars (consistent with the low heat flow values deduced from lithosphere strength), unless heat-producing elements abundances for Mars are subchondritic.
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Smith IB, Putzig NE, Holt JW, Phillips RJ. An ice age recorded in the polar deposits of Mars. Science 2016; 352:1075-8. [PMID: 27230372 DOI: 10.1126/science.aad6968] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 04/19/2016] [Indexed: 11/02/2022]
Abstract
Layered ice deposits at the poles of Mars record a detailed history of accumulation and erosion related to climate processes. Radar investigations measure these layers and provide evidence for climate changes such as ice advance and retreat. We present a detailed analysis of observational data showing that ~87,000 cubic kilometers of ice have accumulated at the poles since the end of the last ice age ~370,000 years ago; this volume is equivalent to a global layer of ~60 centimeters. The majority of the material accumulated at the north pole. These results provide both a means to understand the accumulation history of the polar deposits as related to orbital Milankovitch cycles and constraints for better determination of Mars' past and future climates.
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Affiliation(s)
- Isaac B Smith
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA.
| | - Nathaniel E Putzig
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA
| | - John W Holt
- University of Texas Institute for Geophysics, Jackson School of Geosciences, University of Texas, J. J. Pickle Research Campus, Austin, TX 78758, USA
| | - Roger J Phillips
- Planetary Science Division, Southwest Research Institute, Boulder, CO 80302, USA. McDonnell Center for the Space Sciences and Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130, USA
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Read PL, Lewis SR, Mulholland DP. The physics of Martian weather and climate: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2015; 78:125901. [PMID: 26534887 DOI: 10.1088/0034-4885/78/12/125901] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The planet Mars hosts an atmosphere that is perhaps the closest in terms of its meteorology and climate to that of the Earth. But Mars differs from Earth in its greater distance from the Sun, its smaller size, its lack of liquid oceans and its thinner atmosphere, composed mainly of CO(2). These factors give Mars a rather different climate to that of the Earth. In this article we review various aspects of the martian climate system from a physicist's viewpoint, focusing on the processes that control the martian environment and comparing these with corresponding processes on Earth. These include the radiative and thermodynamical processes that determine the surface temperature and vertical structure of the atmosphere, the fluid dynamics of its atmospheric motions, and the key cycles of mineral dust and volatile transport. In many ways, the climate of Mars is as complicated and diverse as that of the Earth, with complex nonlinear feedbacks that affect its response to variations in external forcing. Recent work has shown that the martian climate is anything but static, but is almost certainly in a continual state of transient response to slowly varying insolation associated with cyclic variations in its orbit and rotation. We conclude with a discussion of the physical processes underlying these long- term climate variations on Mars, and an overview of some of the most intriguing outstanding problems that should be a focus for future observational and theoretical studies.
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Affiliation(s)
- P L Read
- Atmospheric, Oceanic & Planetary Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
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Hutchinson IB, Ingley R, Edwards HGM, Harris L, McHugh M, Malherbe C, Parnell J. Raman spectroscopy on Mars: identification of geological and bio-geological signatures in Martian analogues using miniaturized Raman spectrometers. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2014; 372:rsta.2014.0204. [PMID: 25368350 DOI: 10.1098/rsta.2014.0204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The first Raman spectrometers to be used for in situ analysis of planetary material will be launched as part of powerful, rover-based analytical laboratories within the next 6 years. There are a number of significant challenges associated with building spectrometers for space applications, including limited volume, power and mass budgets, the need to operate in harsh environments and the need to operate independently and intelligently for long periods of time (due to communication limitations). Here, we give an overview of the technical capabilities of the Raman instruments planned for future planetary missions and give a review of the preparatory work being pursued to ensure that such instruments are operated successfully and optimally. This includes analysis of extremophile samples containing pigments associated with biological processes, synthetic materials which incorporate biological material within a mineral matrix, planetary analogues containing low levels of reduced carbon and samples coated with desert varnish that incorporate both geo-markers and biomarkers. We discuss the scientific importance of each sample type and the challenges using portable/flight-prototype instrumentation. We also report on technical development work undertaken to enable the next generation of Raman instruments to reach higher levels of sensitivity and operational efficiency.
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Affiliation(s)
- Ian B Hutchinson
- Department of Physics and Astronomy, Space Research Centre, University of Leicester, Leicester LE1 7RH, UK
| | - Richard Ingley
- Department of Physics and Astronomy, Space Research Centre, University of Leicester, Leicester LE1 7RH, UK
| | - Howell G M Edwards
- Department of Physics and Astronomy, Space Research Centre, University of Leicester, Leicester LE1 7RH, UK
| | - Liam Harris
- Department of Physics and Astronomy, Space Research Centre, University of Leicester, Leicester LE1 7RH, UK
| | - Melissa McHugh
- Department of Physics and Astronomy, Space Research Centre, University of Leicester, Leicester LE1 7RH, UK
| | - Cedric Malherbe
- Department of Physics and Astronomy, Space Research Centre, University of Leicester, Leicester LE1 7RH, UK Department of Inorganic Analytical Chemistry, Chemistry Institute (B6c), University of Liège, 4000 Liège, Belgium
| | - J Parnell
- Department of Geology & Petroleum Geology, University of Aberdeen, King's College, Aberdeen AB24 3UE, UK
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10
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Rummel JD, Beaty DW, Jones MA, Bakermans C, Barlow NG, Boston PJ, Chevrier VF, Clark BC, de Vera JPP, Gough RV, Hallsworth JE, Head JW, Hipkin VJ, Kieft TL, McEwen AS, Mellon MT, Mikucki JA, Nicholson WL, Omelon CR, Peterson R, Roden EE, Sherwood Lollar B, Tanaka KL, Viola D, Wray JJ. A new analysis of Mars "Special Regions": findings of the second MEPAG Special Regions Science Analysis Group (SR-SAG2). ASTROBIOLOGY 2014; 14:887-968. [PMID: 25401393 DOI: 10.1089/ast.2014.1227] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
A committee of the Mars Exploration Program Analysis Group (MEPAG) has reviewed and updated the description of Special Regions on Mars as places where terrestrial organisms might replicate (per the COSPAR Planetary Protection Policy). This review and update was conducted by an international team (SR-SAG2) drawn from both the biological science and Mars exploration communities, focused on understanding when and where Special Regions could occur. The study applied recently available data about martian environments and about terrestrial organisms, building on a previous analysis of Mars Special Regions (2006) undertaken by a similar team. Since then, a new body of highly relevant information has been generated from the Mars Reconnaissance Orbiter (launched in 2005) and Phoenix (2007) and data from Mars Express and the twin Mars Exploration Rovers (all 2003). Results have also been gleaned from the Mars Science Laboratory (launched in 2011). In addition to Mars data, there is a considerable body of new data regarding the known environmental limits to life on Earth-including the potential for terrestrial microbial life to survive and replicate under martian environmental conditions. The SR-SAG2 analysis has included an examination of new Mars models relevant to natural environmental variation in water activity and temperature; a review and reconsideration of the current parameters used to define Special Regions; and updated maps and descriptions of the martian environments recommended for treatment as "Uncertain" or "Special" as natural features or those potentially formed by the influence of future landed spacecraft. Significant changes in our knowledge of the capabilities of terrestrial organisms and the existence of possibly habitable martian environments have led to a new appreciation of where Mars Special Regions may be identified and protected. The SR-SAG also considered the impact of Special Regions on potential future human missions to Mars, both as locations of potential resources and as places that should not be inadvertently contaminated by human activity.
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Affiliation(s)
- John D Rummel
- 1 Department of Biology, East Carolina University , Greenville, North Carolina, USA
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11
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The early heat loss evolution of Mars and their implications for internal and environmental history. Sci Rep 2014; 4:4338. [PMID: 24614056 PMCID: PMC3949296 DOI: 10.1038/srep04338] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 02/20/2014] [Indexed: 11/22/2022] Open
Abstract
The time around 3.7 Ga ago was an epoch when substantial changes in Mars occurred: a substantial decline in aqueous erosion/degradation of landscape features; a change from abundant phyllosilicate formation to abundant acidic and evaporitic mineralogy; a change from olivine-rich volcanism to olivine-pyroxene volcanism; and maybe the cessation of the martian dynamo. Here I show that Mars also experienced profound changes in its internal dynamics in the same approximate time, including a reduction of heat flow and a drastic increasing of lithosphere strength. The reduction of heat flow indicates a limited cooling (or even a heating-up) of the deep interior for post-3.7 Ga times. The drastic increasing of lithosphere strength indicates a cold lithosphere above the inefficiently cooled (or even heated) interior. All those changes experienced by Mars were most probably linked and suggest the existence of profound interrelations between interior dynamics and environmental evolution of this planet.
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12
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Chen JY, Yoo CS. Formation and phase transitions of methane hydrates under dynamic loadings: compression rate dependent kinetics. J Chem Phys 2012; 136:114513. [PMID: 22443783 DOI: 10.1063/1.3695212] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We describe high-pressure kinetic studies of the formation and phase transitions of methane hydrates (MH) under dynamic loading conditions, using a dynamic-diamond anvil cell (d-DAC) coupled with time-resolved confocal micro-Raman spectroscopy and high-speed microphotography. The time-resolved spectra and dynamic pressure responses exhibit profound compression-rate dependences associated with both the formation and the solid-solid phase transitions of MH-I to II and MH-II to III. Under dynamic loading conditions, MH forms only from super-compressed water and liquid methane in a narrow pressure range between 0.9 and 1.6 GPa at the one-dimensional (1D) growth rate of 42 μm/s. MH-I to II phase transition occurs at the onset of water solidification 0.9 GPa, following a diffusion controlled mechanism. We estimated the activation volume to be -109±29 Å(3), primarily associated with relatively slow methane diffusion which follows the rapid interfacial reconstruction, or martensitic displacements of atomic positions and hydrogen bonds, of 5(12)6(2) water cages in MH-I to 4(3)5(12)6(3) cages in MH-II. MH-II to III transition, on the other hand, occurs over a broad pressure range between 1.5 and 2.2 GPa, following a reconstructive mechanism from super-compressed MH-II clathrates to a broken ice-filled viscoelastic solid of MH-III. It is found that the profound dynamic effects observed in the MH formation and phase transitions are primarily governed by the stability of water and ice phases at the relevant pressures.
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Affiliation(s)
- Jing-Yin Chen
- Institute for Shock Physics and Department of Chemistry, Washington State University, Pullman, Washington 99164, USA
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13
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Phillips RJ, Davis BJ, Tanaka KL, Byrne S, Mellon MT, Putzig NE, Haberle RM, Kahre MA, Campbell BA, Carter LM, Smith IB, Holt JW, Smrekar SE, Nunes DC, Plaut JJ, Egan AF, Titus TN, Seu R. Massive CO
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Ice Deposits Sequestered in the South Polar Layered Deposits of Mars. Science 2011; 332:838-41. [DOI: 10.1126/science.1203091] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Roger J. Phillips
- Planetary Science Directorate, Southwest Research Institute, Boulder, CO 80302, USA and Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130, USA
| | - Brian J. Davis
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA
| | - Kenneth L. Tanaka
- Astrogeology Science Center, U.S. Geological Survey, Flagstaff, AZ 86001, USA
| | - Shane Byrne
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA
| | - Michael T. Mellon
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA
| | - Nathaniel E. Putzig
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA
| | - Robert M. Haberle
- Space Science and Astrobiology Division, National Aeronautics and Space Administration (NASA) Ames Research Center, Moffett Field, CA 94035, USA
| | - Melinda A. Kahre
- Bay Area Environmental Research Institute/NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - Bruce A. Campbell
- Center for Earth and Planetary Studies, Smithsonian Institution, Washington, DC 20013, USA
| | - Lynn M. Carter
- Science and Exploration Directorate, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - Isaac B. Smith
- Institute for Geophysics, Jackson School of Geosciences, University of Texas, Austin, TX 78758, USA
| | - John W. Holt
- Institute for Geophysics, Jackson School of Geosciences, University of Texas, Austin, TX 78758, USA
| | - Suzanne E. Smrekar
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Daniel C. Nunes
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Jeffrey J. Plaut
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Anthony F. Egan
- Department of Space Operations, Southwest Research Institute, Boulder, CO 80302, USA
| | - Timothy N. Titus
- Astrogeology Science Center, U.S. Geological Survey, Flagstaff, AZ 86001, USA
| | - Roberto Seu
- Department of Information Engineering, Electronics and Telecommunications, Sapienza University of Rome, 18-00184 Rome, Italy
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14
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Nunes DC, Smrekar SE, Fisher B, Plaut JJ, Holt JW, Head JW, Kadish SJ, Phillips RJ. Shallow Radar (SHARAD), pedestal craters, and the lost Martian layers: Initial assessments. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010je003690] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Stillman DE, Grimm RE. Radar penetrates only the youngest geological units on Mars. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010je003661] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Andrews-Hanna JC, Lewis KW. Early Mars hydrology: 2. Hydrological evolution in the Noachian and Hesperian epochs. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010je003709] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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Nunes DC, Smrekar SE, Safaeinili A, Holt J, Phillips RJ, Seu R, Campbell B. Examination of gully sites on Mars with the shallow radar. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009je003509] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Fairén AG, Davila AF, Lim D, Bramall N, Bonaccorsi R, Zavaleta J, Uceda ER, Stoker C, Wierzchos J, Dohm JM, Amils R, Andersen D, McKay CP. Astrobiology through the ages of Mars: the study of terrestrial analogues to understand the habitability of Mars. ASTROBIOLOGY 2010; 10:821-843. [PMID: 21087162 DOI: 10.1089/ast.2009.0440] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Mars has undergone three main climatic stages throughout its geological history, beginning with a water-rich epoch, followed by a cold and semi-arid era, and transitioning into present-day arid and very cold desert conditions. These global climatic eras also represent three different stages of planetary habitability: an early, potentially habitable stage when the basic requisites for life as we know it were present (liquid water and energy); an intermediate extreme stage, when liquid solutions became scarce or very challenging for life; and the most recent stage during which conditions on the surface have been largely uninhabitable, except perhaps in some isolated niches. Our understanding of the evolution of Mars is now sufficient to assign specific terrestrial environments to each of these periods. Through the study of Mars terrestrial analogues, we have assessed and constrained the habitability conditions for each of these stages, the geochemistry of the surface, and the likelihood for the preservation of organic and inorganic biosignatures. The study of these analog environments provides important information to better understand past and current mission results as well as to support the design and selection of instruments and the planning for future exploratory missions to Mars.
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Attwater J, Wochner A, Pinheiro VB, Coulson A, Holliger P. Ice as a protocellular medium for RNA replication. Nat Commun 2010; 1:76. [PMID: 20865803 DOI: 10.1038/ncomms1076] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Accepted: 08/23/2010] [Indexed: 11/09/2022] Open
Abstract
A crucial transition in the origin of life was the emergence of an informational polymer capable of self-replication and its compartmentalization within protocellular structures. We show that the physicochemical properties of ice, a simple medium widespread on a temperate early Earth, could have mediated this transition prior to the advent of membraneous protocells. Ice not only promotes the activity of an RNA polymerase ribozyme but also protects it from hydrolytic degradation, enabling the synthesis of exceptionally long replication products. Ice furthermore relieves the dependence of RNA replication on prebiotically implausible substrate concentrations, while providing quasicellular compartmentalization within the intricate microstructure of the eutectic phase. Eutectic ice phases had previously been shown to promote the de novo synthesis of nucleotide precursors, as well as the condensation of activated nucleotides into random RNA oligomers. Our results support a wider role for ice as a predisposed environment, promoting all the steps from prebiotic synthesis to the emergence of RNA self-replication and precellular Darwinian evolution.
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Affiliation(s)
- James Attwater
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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Clifford SM, Lasue J, Heggy E, Boisson J, McGovern P, Max MD. Depth of the Martian cryosphere: Revised estimates and implications for the existence and detection of subpermafrost groundwater. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009je003462] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Onset and migration of spiral troughs on Mars revealed by orbital radar. Nature 2010; 465:450-3. [PMID: 20505722 DOI: 10.1038/nature09049] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 03/11/2010] [Indexed: 11/08/2022]
Abstract
The landscape of the north polar layered deposits of Mars (NPLD) is dominated by a pinwheel array of enigmatic spiral troughs. The troughs have intrigued planetary scientists since the Mariner 9 spacecraft returned the first close-up image in 1972, but conclusive evidence of their origin has remained elusive. Debate continues regarding all aspects of the troughs, including the possibility that they have migrated, their age in relation to the current NPLD surface, and whether they are fundamentally erosional or constructional features. The troughs are probably related to climatic processes, yet the nature of this relationship has remained a mystery. Previous data characterizing only the exposed NLPD surface were insufficient to test these hypotheses. Here we show that the central spiral troughs initiated after deposition of three-quarters of the NPLD, quickly reached a stable morphology and migrated approximately 65 kilometres poleward and 600 metres in altitude over the past two million years or so. Our radar stratigraphy rules out hypotheses of erosional incision post-dating deposition, and instead largely validates an early hypothesis for constructional trough migration with wind transport and atmospheric deposition as dominant processes. These results provide hard constraints for palaeo-climate models and a new context for evaluating imagery, spectral data, and now radar sounding data, the better to understand the link between orbital parameters and climate, the role of climate in shaping the polar ice of Mars, and eventually, the age of the polar deposits themselves.
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Holt JW, Fishbaugh KE, Byrne S, Christian S, Tanaka K, Russell PS, Herkenhoff KE, Safaeinili A, Putzig NE, Phillips RJ. The construction of Chasma Boreale on Mars. Nature 2010; 465:446-9. [PMID: 20505721 DOI: 10.1038/nature09050] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 03/10/2010] [Indexed: 11/09/2022]
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Grott M, Breuer D. On the spatial variability of the Martian elastic lithosphere thickness: Evidence for mantle plumes? ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009je003456] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Fisher DA, Hecht MH, Kounaves SP, Catling DC. A perchlorate brine lubricated deformable bed facilitating flow of the north polar cap of Mars: Possible mechanism for water table recharging. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009je003405] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Kadish SJ, Barlow NG, Head JW. Latitude dependence of Martian pedestal craters: Evidence for a sublimation-driven formation mechanism. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008je003318] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Seth J. Kadish
- Department of Geological Sciences; Brown University; Providence Rhode Island USA
| | - Nadine G. Barlow
- Department of Physics and Astronomy; Northern Arizona University; Flagstaff Arizona USA
| | - James W. Head
- Department of Geological Sciences; Brown University; Providence Rhode Island USA
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Pham LBS, Karatekin O, Dehant V. Effects of meteorite impacts on the atmospheric evolution of Mars. ASTROBIOLOGY 2009; 9:45-54. [PMID: 19317624 DOI: 10.1089/ast.2008.0242] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Early in its history, Mars probably had a denser atmosphere with sufficient greenhouse gases to sustain the presence of stable liquid water at the surface. Impacts by asteroids and comets would have played a significant role in the evolution of the martian atmosphere, not only by causing atmospheric erosion but also by delivering material and volatiles to the planet. We investigate the atmospheric loss and the delivery of volatiles with an analytical model that takes into account the impact simulation results and the flux of impactors given in the literature. The atmospheric loss and the delivery of volatiles are calculated to obtain the atmospheric pressure evolution. Our results suggest that the impacts alone cannot satisfactorily explain the loss of significant atmospheric mass since the Late Noachian (approximately 3.7-4 Ga). A period with intense bombardment of meteorites could have increased the atmospheric loss; but to explain the loss of a speculative massive atmosphere in the Late Noachian, other factors of atmospheric erosion and replenishment also need to be taken into account.
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Holt JW, Safaeinili A, Plaut JJ, Head JW, Phillips RJ, Seu R, Kempf SD, Choudhary P, Young DA, Putzig NE, Biccari D, Gim Y. Radar sounding evidence for buried glaciers in the southern mid-latitudes of Mars. Science 2008; 322:1235-8. [PMID: 19023078 DOI: 10.1126/science.1164246] [Citation(s) in RCA: 297] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Lobate features abutting massifs and escarpments in the middle latitudes of Mars have been recognized in images for decades, but their true nature has been controversial, with hypotheses of origin such as ice-lubricated debris flows or glaciers covered by a layer of surface debris. These models imply an ice content ranging from minor and interstitial to massive and relatively pure. Soundings of these deposits in the eastern Hellas region by the Shallow Radar on the Mars Reconnaissance Orbiter reveal radar properties entirely consistent with massive water ice, supporting the debris-covered glacier hypothesis. The results imply that these glaciers formed in a previous climate conducive to glaciation at middle latitudes. Such features may collectively represent the most extensive nonpolar ice yet recognized on Mars.
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Affiliation(s)
- John W Holt
- Institute for Geophysics, Jackson School of Geosciences, University of Texas, Austin, TX 78758, USA.
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Affiliation(s)
- Matthias Grott
- Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstraße 2, 12489 Berlin, Germany
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