DOCSLIB.ORG

Zero-Valent Iron on Mars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Zero-Valent Iron on Mars Zero-Valent Iron on Mars: An Alternative Energy Source for Methanogens Courtesy: NASA Brendon K. Chastain University of Arkansas Dept. of Biological Sciences Methanogens – Good Model for Possible Subsurface Life on Mars • Can grow in temperatures below 0 C (Reid et al., 2006) • Can tolerate exposure to extremely low pressures (Altheide and Kral, 2008) • Phylogenetically primitive *Mars in a laboratory! Æ Fe0 on Mars • Several large iron meteorites composed primarily of Fe0 found on Mars’ surface. (Schroder et al., 2008) • Stony-irons containing substantial Fe0 also found in what might be a strewn field. (Schroder et al., 2008) Courtesy: NASA/CORNELL Micrometeorite Delivery • Just like Earth, Mars is bombarded with meteoritic debris, much of it Fe0. – Substantially thinner atmosphere increases the amount reaching the surface • Flynn and McKay (1990) estimate as much as 29% of Martian soil from meteorites. – Up to 59,000 tons per year delivered to the surface Shock-reduction from Impacts • Impacts can lead to 1 shock-reduction of iron- bearing minerals resulting in nanophase Fe0. • Numerous studies confirm Fe0 in SNC meteorites. (e.g. Kurihara et al., 2009) • This has been mimicked in the laboratory using JSC Mars-1 regolith 1) TEM image of NWA 2737 olivine. Small, dark (electron-dense) spherules simulant. (Moroz et al., are consistent with α-iron kamacite [after 2009) Treiman et al., 2007] (Pieters et al., 2008) Fe0 Source Summary • Large meteorites deliver exogenous Fe0 • Micrometeorites deliver exogenous Fe0 • Large impactors generate and spread nanophase Fe0 due to shock-reduction of iron-bearing minerals • May lead to substantial buildup of Fe0 over time Fe0 Relationship to Methanogens • Protons in solution can react with Fe0 to produce H2, but the reaction is not thermodynamically favorable. • However, a sink for H2 can drive the reaction. • Daniels et al. (1987) show that methanogens in nutritive medium can utilize the H2. Daniels et al. (1987) This Study: •Fe0/any H+ in solution (energy) • Bicarbonate buffer/CO2 (carbon/water) • Montmorillonite clay (micronutrients) • Does methanogenic metabolism take place in these Mars-relevant conditions? *Why montmorillonite? 14 30 M. formicicum M. barkeri Transfer #1 12 Montmorillonite Montmorillonite 25 Transfer #1 10 Transfer #2 JSC Mars-1 JSC Mars-1 20 8 JSC Mars-2 JSC Mars-2 15 Transfer #2 6 Jarosite Jarosite Methane (% vol.) Methane Methane (%vol.) 10 4 Nontronite Nontronite 2 Buffer-only 5 Buffer-only 0 0 1 3 5 7 9 1113151719212325272931 1 3 5 7 9 1113151719212325272931 Time (weeks) Time (weeks) 90 M. wolfeii 80 Montmorillonite Montmorillonite 70 Transfer #1 JSC Mars-1 60 clay can supply 50 Transfer #2 JSC Mars-2 the micronutrient 40 Jarosite Methane (% vol.) (% Methane 30 Nontronite requirements of 20 Buffer-only 10 methanogens. 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 Time (weeks) 0 Results: Fe vs. no H2 40 35 30 25 Feº-included 20 Control 15 Methane Concentration (% vol.) (% Concentration Methane 10 5 0 0 102030405060708090100 Time (days) Obvious oxidation to Fe3+ *Is the darker color of the montmorillonite an indication of Fe(OH)2? Comparison to Previous Work 40 30 Initial study before transfer 20 Initial study after transfer Feº-included Methane Concentration (% vol.) Concentration (% Methane 10 0 020406080100 Time (days) Concluding Remarks •Fe0 is available on Mars •CO2 is available on Mars • Montmorillonite-like clays are available on Mars • Given the right environmental conditions, these three materials can support methanogenic metabolism • The temperature was not exactly Mars- relevant, BUT….
Load more

Recommended publications
  • March 21–25, 2016
    FORTY-SEVENTH LUNAR AND PLANETARY SCIENCE CONFERENCE PROGRAM OF TECHNICAL SESSIONS MARCH 21–25, 2016 The Woodlands Waterway Marriott Hotel and Convention Center The Woodlands, Texas INSTITUTIONAL SUPPORT Universities Space Research Association Lunar and Planetary Institute National Aeronautics and Space Administration CONFERENCE CO-CHAIRS Stephen Mackwell, Lunar and Planetary Institute Eileen Stansbery, NASA Johnson Space Center PROGRAM COMMITTEE CHAIRS David Draper, NASA Johnson Space Center Walter Kiefer, Lunar and Planetary Institute PROGRAM COMMITTEE P. Doug Archer, NASA Johnson Space Center Nicolas LeCorvec, Lunar and Planetary Institute Katherine Bermingham, University of Maryland Yo Matsubara, Smithsonian Institute Janice Bishop, SETI and NASA Ames Research Center Francis McCubbin, NASA Johnson Space Center Jeremy Boyce, University of California, Los Angeles Andrew Needham, Carnegie Institution of Washington Lisa Danielson, NASA Johnson Space Center Lan-Anh Nguyen, NASA Johnson Space Center Deepak Dhingra, University of Idaho Paul Niles, NASA Johnson Space Center Stephen Elardo, Carnegie Institution of Washington Dorothy Oehler, NASA Johnson Space Center Marc Fries, NASA Johnson Space Center D. Alex Patthoff, Jet Propulsion Laboratory Cyrena Goodrich, Lunar and Planetary Institute Elizabeth Rampe, Aerodyne Industries, Jacobs JETS at John Gruener, NASA Johnson Space Center NASA Johnson Space Center Justin Hagerty, U.S. Geological Survey Carol Raymond, Jet Propulsion Laboratory Lindsay Hays, Jet Propulsion Laboratory Paul Schenk,
    [Show full text]
  • Space Resources Roundtable II : November 8-10, 2000, Golden, Colorado
    SPACE RESOURCES RouNDTABLE II November 8-10, 2000 Colorado School of Mines Golden, Colorado LPI Contribution No. 1070 SPACE RESOURCES ROUNDTABLE II November 8-10, 2000 Golden, Colorado Sponsored by Colorado School of Mines Lunar and Planetary Institute National Aeronautics and Space Administration Steering Committee Joe Burris, WorldTradeNetwork.net David Criswell, University of Houston Michael B. Duke, Lunar and Planetary Institute Mike O'Neal, NASA Kennedy Space Center Sanders Rosenberg, InSpace Propulsion, Inc. Kevin Reed, Marconi, Inc. Jerry Sanders, NASA Johnson Space Center Frank Schowengerdt, Colorado School of Mines Bill Sharp, Colorado School of Mines LPI Contribution No. 1070 Compiled in 2000 by LUNAR AND PLANETARY INSTITUTE The Institute is operated by the Universities Space Research Association under Contract No. NASW-4574 with the National Aeronautics and Space Administration. Matenal in this volume may be copied wnhout restraint for library, abstract service, education. or personal research purposes; however, republication of any paper or portion thereof requ1res the wriuen permission of the authors as well as the appropnate acknowledgment of this publication. Abstracts in this volume may be cited as Author A B. (2000) Title of abstract. In Space Resources Roundtable II. p x.x . LPI Contnbuuon No. 1070. Lunar and Planetary Institute. Houston. This repon is distributed by ORDER DEPARTMENT Lunar and Planetary Institute 3600 Bay Area Boulevard Houston TX 77058-1113 Phone: 281-486-2172 Fax: 281-486-2186 E-mail: [email protected] Mail order requestors will be invoiced for the cost of shipping and handling. LPI Contribution No 1070 iii Preface This volume contains abstracts that have been accepted for presentation at the Space Resources Roundtable II, November 8-10, 2000.
    [Show full text]
  • High Survivability of Micrometeorites on Mars: Sites with Enhanced Availability of Limiting Nutrients
    RESEARCH ARTICLE High Survivability of Micrometeorites on Mars: Sites With 10.1029/2019JE006005 Enhanced Availability of Limiting Nutrients Key Points: Andrew G. Tomkins1 , Matthew J. Genge2,3 , Alastair W. Tait1,4 , Sarah L. Alkemade1, • Micrometeorites are predicted to be 1 1 5 far more abundant on Mars than on Andrew D. Langendam , Prudence P. Perry , and Siobhan A. Wilson Earth 1 2 • Micrometeorites are concentrated in School of Earth, Atmosphere and Environment, Melbourne, Victoria, Australia, Impact and Astromaterials Research the residue of aeolian sediment Centre, Department of Earth Science and Engineering, Imperial College London, London, UK, 3Department of removal, such as at bedrock cracks Mineralogy, The Natural History Museum, London, UK, 4Department of Biological and Environmental Sciences, and gravel accumulations University of Stirling, Scotland, UK, 5Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, • Micrometeorite accumulation sites are enriched in key nutrients for Alberta, Canada primitive microbes: reduced phosphorus, sulfur, and iron Abstract NASA's strategy in exploring Mars has been to follow the water, because water is essential for life, and it has been found that there are many locations where there was once liquid water on the surface. Now perhaps, to narrow down the search for life on a barren basalt‐dominated surface, there needs to be a Correspondence to: A. G. Tomkins, refocusing to a strategy of “follow the nutrients.” Here we model the entry of metallic micrometeoroids [email protected] through the Martian atmosphere, and investigate variations in micrometeorite abundance at an analogue site on the Nullarbor Plain in Australia, to determine where the common limiting nutrients available in Citation: these (e.g., P, S, Fe) become concentrated on the surface of Mars.
    [Show full text]
  • Connection Between Micrometeorites and Wild 2 Particles: from Antarctic Snow to Cometary Ices
    Meteoritics & Planetary Science 44, Nr 10, 1643–1661 (2009) Abstract available online at http://meteoritics.org Connection between micrometeorites and Wild 2 particles: From Antarctic snow to cometary ices E. DOBRIC√1,*, C. ENGRAND1, J. DUPRAT1, M. GOUNELLE2, H. LEROUX3, E. QUIRICO4, and J.-N. ROUZAUD5 1Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, CNRS-Univ. Paris Sud, 91405 Orsay Campus, France 2Laboratoire de Minéralogie et de Cosmochimie, Muséum National d’Histoire Naturelle, 57 rue Cuvier, CP52, 75005 Paris, France 3Laboratoire de Structure et Propriétés de l’Etat Solide, CNRS-Univ. des Sciences et Technologies de Lille, 59655 Villeneuve d’Ascq, France 4Laboratoire de Planétologie de Grenoble, Univ. J. Fourier CNRS-INSU 38041 Grenoble Cedex 09, France 5Laboratoire de Géologie, Ecole Normale Supérieure, CNRS, 75231 Paris Cedex 5, France *Corresponding author. E-mail: [email protected] (Received 17 March 2009; revision accepted 21 September 2009) Abstract–We discuss the relationship between large cosmic dust that represents the main source of extraterrestrial matter presently accreted by the Earth and samples from comet 81P/Wild 2 returned by the Stardust mission in January 2006. Prior examinations of the Stardust samples have shown that Wild 2 cometary dust particles contain a large diversity of components, formed at various heliocentric distances. These analyses suggest large-scale radial mixing mechanism(s) in the early solar nebula and the existence of a continuum between primitive asteroidal and cometary matter. The recent collection of CONCORDIA Antarctic micrometeorites recovered from ultra-clean snow close to Dome C provides the most unbiased collection of large cosmic dust available for analyses in the laboratory.
    [Show full text]
  • Finegrained Precursors Dominate the Micrometeorite Flux
    Meteoritics & Planetary Science 47, Nr 4, 550–564 (2012) doi: 10.1111/j.1945-5100.2011.01292.x Fine-grained precursors dominate the micrometeorite flux Susan TAYLOR1*, Graciela MATRAJT2, and Yunbin GUAN3 1Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, New Hampshire 03755–1290, USA 2University of Washington, Seattle, Washington 98105, USA 3Geological & Planetary Sciences MC 170-25, Caltech, Pasadena, California 91125, USA *Corresponding author. E-mail: [email protected] (Received 15 May 2011; revision accepted 22 September 2011) Abstract–We optically classified 5682 micrometeorites (MMs) from the 2000 South Pole collection into textural classes, imaged 2458 of these MMs with a scanning electron microscope, and made 200 elemental and eight isotopic measurements on those with unusual textures or relict phases. As textures provide information on both degree of heating and composition of MMs, we developed textural sequences that illustrate how fine-grained, coarse-grained, and single mineral MMs change with increased heating. We used this information to determine the percentage of matrix dominated to mineral dominated precursor materials (precursors) that produced the MMs. We find that at least 75% of the MMs in the collection derived from fine-grained precursors with compositions similar to CI and CM meteorites and consistent with dynamical models that indicate 85% of the mass influx of small particles to Earth comes from Jupiter family comets. A lower limit for ordinary chondrites is estimated at 2–8% based on MMs that contain Na-bearing plagioclase relicts. Less than 1% of the MMs have achondritic compositions, CAI components, or recognizable chondrules. Single mineral MMs often have magnetite zones around their peripheries.
    [Show full text]
  • AN ACHONDRITIC MICROMETEORITE from ANTARCTICA: EXPANDING the SOLAR SYSTEM INVENTORY of BASALTIC ASTEROIDS. M. Gounelle1,2,3, C. Engrand2, M
    Lunar and Planetary Science XXXVI (2005) 1655.pdf AN ACHONDRITIC MICROMETEORITE FROM ANTARCTICA: EXPANDING THE SOLAR SYSTEM INVENTORY OF BASALTIC ASTEROIDS. M. Gounelle1,2,3, C. Engrand2, M. Chaussidon4, M.E. Zolensky5 and M. Maurette2. 1Université Paris XI, 91 405 Orsay, France ([email protected]), 2CSNSM. Bâtiment 104, 91 405 Orsay, France.3Department of Mineralogy, The Natural History Museum, London, UK. 4CRPG-CNRS, BP20, 54501 Vandoeuvre les Nancy, France. 5KT, NASA Johnson Space Center, Houston, Texas 77058, USA. Introduction: Micrometeorites with sizes below 1 mm 100.0 are collected in a diversity of environments such as deep-sea sediments and polar caps [1]. Chemical, mineralogical and isotopic studies indicate that micrometeorites are closely related to primitive CI / carbonaceous chondrites that amount to only ~2 % of 10.0 meteorite falls [1]. While thousands of REE micrometeorites have been studied in detail, no micrometeorite has been found so far with an unambiguous achondritic composition and texture. 1.0 One melted cosmic spherule has a low Fe/Mn ratio La Ce Pr Nd Sm Eu Gd Dy Er Yb Lu similar to that of eucrites, the most common basaltic Figure 2: REE abundance pattern of pyroxene in meteorite group [2]. Here we report on the texture, MM40 measured with the ims3f ion microprobe at mineralogy, Rare Earth Elements (REEs) abundance CRPG Nancy. and oxygen isotopic composition of the unmelted Antarctic micrometeorite 99-21-40 that has an Pyroxene in MM40 is enriched by a factor of 10 in unambiguous basaltic origin. REEs relative to CI chondrites. The REE abundance pattern is fractionated with a gradual increase from light to heavy REEs.
    [Show full text]
  • Near Earth Asteroid Rendezvous: Mission Summary 351
    Cheng: Near Earth Asteroid Rendezvous: Mission Summary 351 Near Earth Asteroid Rendezvous: Mission Summary Andrew F. Cheng The Johns Hopkins Applied Physics Laboratory On February 14, 2000, the Near Earth Asteroid Rendezvous spacecraft (NEAR Shoemaker) began the first orbital study of an asteroid, the near-Earth object 433 Eros. Almost a year later, on February 12, 2001, NEAR Shoemaker completed its mission by landing on the asteroid and acquiring data from its surface. NEAR Shoemaker’s intensive study has found an average density of 2.67 ± 0.03, almost uniform within the asteroid. Based upon solar fluorescence X-ray spectra obtained from orbit, the abundance of major rock-forming elements at Eros may be consistent with that of ordinary chondrite meteorites except for a depletion in S. Such a composition would be consistent with spatially resolved, visible and near-infrared (NIR) spectra of the surface. Gamma-ray spectra from the surface show Fe to be depleted from chondritic values, but not K. Eros is not a highly differentiated body, but some degree of partial melting or differentiation cannot be ruled out. No evidence has been found for compositional heterogeneity or an intrinsic magnetic field. The surface is covered by a regolith estimated at tens of meters thick, formed by successive impacts. Some areas have lesser surface age and were apparently more recently dis- turbed or covered by regolith. A small center of mass offset from the center of figure suggests regionally nonuniform regolith thickness or internal density variation. Blocks have a nonuniform distribution consistent with emplacement of ejecta from the youngest large crater.
    [Show full text]
  • Cometary Micrometeorites and Input of Prebiotic Compounds
    BIO Web of Conferences 2, 03003 (2014) DOI: 10.1051/bioconf/20140203003 C Owned by the authors, published by EDP Sciences, 2014 Cometary micrometeorites and input of prebiotic compounds C. Engrand1 1CSNSM CNRS/IN2P3-Univ. Paris Sud, Bat. 104, 91405 Orsay Campus, France Abstract. The apparition of life on the early Earth was probably favored by inputs of extraterrestrial matter brought by carbonaceous chondrite-like objects or cometary material. Interplanetary dust collected nowadays on Earth is related to carbonaceous chondrites and to cometary material. They contain in particular at least a few percent of organic matter, organic compounds (amino-acids, PAHs,…), hydrous silicates, and could have largely contributed to the budget of prebiotic matter on Earth, about 4 Ga ago. A new population of cometary dust was recently discovered in the Concordia Antarctic micrometeorite collection. These "Ultracarbonaceous Antarctic Micro- meteorites" (UCAMMs) are dominated by deuterium-rich and nitrogen-rich organic matter. They seem related to the "CHON" grains identified in the comet Halley in 1986. Although rare in the micrometeorites flux (<5% of the micrometeorites), UCAMMs could have significantly contributed to the input of prebiotic matter. Their content in soluble organic matter is currently under study. 1 Introduction Interplanetary dust originating from asteroids and comets could have contributed to the origin of life on Earth [e.g.1; 2 and references therein]. They could have brought prebiotic material that was used to favor the origin of life on Earth. Cosmic dust also seeded other planetary bodies where life could have emerged as well, such as Mars, Titan, Europa or Enceladus… The origin of interplanetary dust is dual, from asteroids and comets [e.g.
    [Show full text]
  • Science Concept 7: the Moon Is a Natural Laboratory for Regolith Processes and Weathering on Anhydrous Airless Bodies
    Science Concept 7: The Moon is a Natural Laboratory for Regolith Processes and Weathering on Anhydrous Airless Bodies Science Concept 7: The Moon is a natural laboratory for regolith processes and weathering on anhydrous airless bodies Science Goals: a. Search for and characterize ancient regolith. b. Determine the physical properties of the regolith at diverse locations of expected human activity. c. Understand regolith modification processes (including space weathering), particularly deposition of volatile materials. d. Separate and study rare materials in the lunar regolith. INTRODUCTION The Moon is unmodified by processes that have changed other terrestrial planets, including Mars, and thus offers a pristine history of evolution of the terrestrial planets. Though Mars demonstrates the evolution of a warm, wet planet, water is an erosive substance that can erase a planet‘s geological history. The Moon, on the other hand, is anhydrous. It has never had liquid water on its surface. The Moon is also airless, as opposed to the Venus, the Earth, and Mars. An atmosphere, too, is a weathering component that can distort a planet‘s geologic history. Thus, the Moon offers a pristine history of the evolution of terrestrial planets that can increase our understanding of the formation of all rocky bodies, including the Earth. Additionally, the Moon offers many resources that can be exploited, from metals like iron and titanium to implanted volatiles like hydrogen and helium. There is evidence for water at the poles in permanently shadowed regions (PSRs) (Nozette et al., 1996). Such volatiles could not only support human exploration and habitation on the Moon, but they could also be the constituents for fuel or fuel cells to propel explorers to farther reaches of the Solar System (NRC, 2007).
    [Show full text]
  • Mineralogies and Source Regions of Near-Earth Asteroids ⇑ Tasha L
    Icarus 222 (2013) 273–282 Contents lists available at SciVerse ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus Mineralogies and source regions of near-Earth asteroids ⇑ Tasha L. Dunn a, , Thomas H. Burbine b, William F. Bottke Jr. c, John P. Clark a a Department of Geography-Geology, Illinois State University, Normal, IL 61790, United States b Department of Astronomy, Mount Holyoke College, South Hadley, MA 01075, United States c Southwest Research Institute, Boulder, CO 80302, United States article info abstract Article history: Near-Earth Asteroids (NEAs) offer insight into a size range of objects that are not easily observed in the Received 8 October 2012 main asteroid belt. Previous studies on the diversity of the NEA population have relied primarily on mod- Revised 8 November 2012 eling and statistical analysis to determine asteroid compositions. Olivine and pyroxene, the dominant Accepted 8 November 2012 minerals in most asteroids, have characteristic absorption features in the visible and near-infrared Available online 21 November 2012 (VISNIR) wavelengths that can be used to determine their compositions and abundances. However, formulas previously used for deriving compositions do not work very well for ordinary chondrite Keywords: assemblages. Because two-thirds of NEAs have ordinary chondrite-like spectral parameters, it is essential Asteroids, Composition to determine accurate mineralogies. Here we determine the band area ratios and Band I centers of 72 Meteorites Spectroscopy NEAs with visible and near-infrared spectra and use new calibrations to derive the mineralogies 47 of these NEAs with ordinary chondrite-like spectral parameters. Our results indicate that the majority of NEAs have LL-chondrite mineralogies.
    [Show full text]
  • Kuiper Belt and Comets: an Observational Perspective
    Kuiper Belt and Comets: An Observational Perspective David Jewitt1 1. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 [email protected] Note to the Reader These notes outline a series of lectures given at the Saas Fee Winter School held in Murren, Switzerland, in March 2005. As I see it, the main aim of the Winter School is to communicate (especially) with young people in order to inflame their interests in science and to encourage them to see ways in which they can contribute and maybe do a better job than we have done so far. With this in mind, I have written up my lectures in a less than formal but hopefully informative and entertaining style, and I have taken a few detours to discuss subjects that I think are important but which are usually glossed-over in the scientific literature. 1 Preamble Almost exactly 400 years ago, planetary astronomy kick-started the era of modern science, with a series of remarkable discoveries by Galileo concerning the surfaces of the Moon and Sun, the phases of Venus, and the existence and motions of Jupiter’s large satellites. By the early 20th century, the fo- cus of astronomical attention had turned to objects at larger distances, and to questions of galactic structure and cosmological interest. At the start of the 21st century, the tide has turned again. The study of the Solar system, particularly of its newly discovered outer parts, is one of the hottest topics in modern astrophysics with great potential for revealing fundamental clues about the origin of planets and even the emergence of life.
    [Show full text]
  • Moon-Miners-Manifesto-Mars.Pdf
    http://www.moonsociety.org/mars/ Let’s make the right choice - Mars and the Moon! Advantages of a low profile for shielding Mars looks like Arizona but feels like Antarctica Rover Opportunity at edge of Endeavor Crater Designing railroads and trains for Mars Designing planes that can fly in Mars’ thin air Breeding plants to be “Mars-hardy” Outposts between dunes, pulling sand over them These are just a few of the Mars-related topics covered in the past 25+ years. Read on for much more! Why Mars? The lunar and Martian frontiers will thrive much better as trading partners than either could on it own. Mars has little to trade to Earth, but a lot it can trade with the Moon. Both can/will thrive together! CHRONOLOGICAL INDEX MMM THEMES: MARS MMM #6 - "M" is for Missing Volatiles: Methane and 'Mmonia; Mars, PHOBOS, Deimos; Mars as I see it; MMM #16 Frontiers Have Rough Edges MMM #18 Importance of the M.U.S.-c.l.e.Plan for the Opening of Mars; Pavonis Mons MMM #19 Seizing the Reins of the Mars Bandwagon; Mars: Option to Stay; Mars Calendar MMM #30 NIMF: Nuclear rocket using Indigenous Martian Fuel; Wanted: Split personality types for Mars Expedition; Mars Calendar Postscript; Are there Meteor Showers on Mars? MMM #41 Imagineering Mars Rovers; Rethink Mars Sample Return; Lunar Development & Mars; Temptations to Eco-carelessness; The Romantic Touch of Old Barsoom MMM #42 Igloos: Atmosphere-derived shielding for lo-rem Martian Shelters MMM #54 Mars of Lore vs. Mars of Yore; vendors wanted for wheeled and walking Mars Rovers; Transforming Mars; Xities
    [Show full text]