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Meteorites on Mars: Implications from Three Probably Paired Meteorite Candidates at
Where: 72nd Annual Meteoritical Society Meeting, Nancy, France Dates: 13th July 2009 - 18th July 2009 When: 15th July 2009, 4pm - 5pm
C. Schröder, J.W. Ashley, I. Fleischer, R. Gellert, G. Klingelhöfer, P. A. deSouza Jr. and the Athena Science Team
Introduction:
The Mars Exploration Rover (MER) Opportunity has come across several possible meteorites, among them the only officially recognized meteorite on another planet, the IAB iron meteorite Meridiani Planum [1]. Three meteorite candidate rocks investigated by Opportunity - informally dubbed Barberton, Santa Catarina and Santorini by the MER team - have very similar chemical and mineralogical compositions and are probably paired [1-3]. We discuss the implications for the Meridiani Planum terrain.
Results and Discussion:
High Ni contents and the minerals kamacite and troilite detected in Barberton, Santa Catarina and Santorini by Opportunity’s Alpha Particle X-ray (APXS) and Mössbauer spectrometers provide evidence for a meteoritic origin [1-3]. The chemical composition of the three rocks is most consistent with mesosiderite silicate clasts [1-2]. It is also possible that these rocks represent a new class of meteorite not yet encountered on Earth. Because of the similarity in composition and because mesosiderites are a relatively rare group of meteorites, the three rocks are probably fragments of the same larger body and thus paired. The three rocks were investigated serendipitously several kilometers apart from each other, suggesting a larger population of similar rock fragments in this area and that Opportunity may be driving across a meteorite strewn field. Victoria crater is ~800 m in diameter and was investigated extensively by Opportunity [4]. Barberton, with a long-axis of ~3 cm is the smallest fragment of the three, and was encountered at the rim of Endurance crater, ~7 km to the north of Victoria crater. Santa Catarina and the surrounding cobble field are located at the Cabo Anonimo promontory on the northwestern rim of Victoria. The cobbles in the Santa Catarina field appear to be of similar composition on the basis of Miniature Thermal Emission Spectrometer (Mini-TES) and multispectral Panoramic Camera (Pancam) data. Santorini was discovered ~800 m south of Victoria. Because 1) the largest observed accumulation of rock fragments of this kind is at the rim of Victoria, and 2) the population as a whole appears to surround Victoria, it is possible that Barberton, Santa Catarina and Santorini are associated in some way with the impactor that created Victoria crater. If these rocks are unrelated to the formation of Victoria and fell later, a strewn field would not necessarily stop at the crater rim. Thus, finding another fragment on the floor of Victoria would argue against this hypothesis, but rover mobility constraints precluded such investigations. The full distribution of these fragments may also allow conclusions on the properties of the impactor, the formation of Victoria crater, or the thickness of the atmosphere at the time of the fall.
LikeIn Situ Mössbauer Spectroscopy on Earth, Mars, and Beyond
Where: 24th International Applied Geochemistry Symposium, Fredericton, New Brunswick, Canada Dates: 1st June 2009 - 4th June 2009 When: 3rd June 2009
C. Schröder, G. Klingelhöfer, R.V. Morris, B. Bernhardt, M. Blumers, I. Fleischer, D.S. Rodionov, and J. Gironés López; Published in Proceedings of the 24th International Applied Geochemistry Symposium, 821-824
Iron occurs naturally as Fe2+, Fe3+, and, to a lesser extent, as Fe(0). Many fundamental (bio)geochemical processes are based on redox cycling between these oxidation states. Mössbauer spectroscopy provides quantitative information about the distribution of Fe among its oxidation states, identification of Fe-bearing phases, and relative distribution of Fe among those phases. Determination of Fe3+/FeTotal and the identification of iron hydroxide mineral phases, for example, provide evidence for aqueous activity on the surface of Mars. Metallic iron identified in several rocks investigated on Mars suggests a meteoritic origin. These Mössbauer spectra were obtained with portable, miniaturized spectrometers on board the NASA Mars Exploration Rovers. Because of their backscattering measurement geometry, the instruments are directly placed on the sample surface to be analyzed by a robotic arm. In field studies on Earth, similar instruments have been used for the in situ study of green rust in soil, and as a prospecting tool and process monitor during field testing of precursor hardware for lunar in situ resource utilization (oxygen production). An advanced version of the Mars spectrometer has a new detector system permitting shorter measurement times and the capability for simultaneous acquisition of X-ray fluorescence spectra to determine elemental compositions.
Where: Lunarbase Symposium, Kaiserslautern, Germany Dates: 12th May 2009 - 13th May 2009 When: 13th May 2009
C. Schröder, R.V. Morris, T.G. Graff, G.B. Sanders, K.A. Lee, T.M. Simon, W.E. Larson, J.W. Quinn, L.D. Clark, and J.J. Caruso
Essential consumables like oxygen must to be produced from materials on the lunar surface to enable a sustained, long-term presence of humans on the Moon. The Outpost Precursor for ISRU and Modular Architecture (OPTIMA) field test on Mauna Kea, Hawaii, facilitated by the Pacific International Space Center for Exploration Systems (PISCES) of the University of Hawaii at Hilo, was designed to test the implementation of three hardware concepts to extract oxygen from the lunar regolith: Precursor ISRU Lunar Oxygen Testbed (PILOT) developed by Lockheed Martin in Littleton, CO; Regolith & Environmental Science and Oxygen & Lunar Volatiles Extraction (RESOLVE) developed at the NASA Kennedy Space Center in Cape Canaveral, FL; and ROxygen developed at the NASA Johnson Space Center in Houston, TX. The three concepts differ in design, but all rely on the same general principle: hydrogen reduction of metal cations (primarily Fe2+) bonded to oxygen to metal (e.g., Fe(0)) with the production of water. The hydrogen source is residual hydrogen in the fuel tanks of lunar landers. Electrolysis of the water produces oxygen and hydrogen (which is recycled). We used the miniaturized Mössbauer spectrometer MIMOS II to quantify the yield of this process on the basis of the quantity of Fe(0) produced. Iron Mössbauer spectroscopy identifies iron-bearing phases, determines iron oxidation states, and quantifies the distribution of iron between mineral phases and oxidation states. The oxygen yield can be calculated by quantitative measurements of the distribution of Fe among oxidation states in the regolith before and after hydrogen reduction. A Mössbauer spectrometer can also be used as a prospecting tool to select the optimum feedstock for the oxygen production plants (e.g., high total Fe content and easily reduced phases). As a demonstration, a MIMOS II backscatter spectrometer (SPESI, Germany) was mounted on the Cratos rover (NASA Glenn Research Center in Cleveland, OH), which is one of several rover concepts designed to excavate and transfer regolith to the stationary hydrogen reduction plants. Spaceflight versions of the MIMOS II are part of the instrument payloads of NASA’s Mars Exploration Rovers and still operating five years after landing on the surface of the planet. MIMOS II was also selected for Phobos-Grunt, a Russian sample return mission to the martian moon Phobos scheduled to launch in 2009, and ESA’s ExoMars rover, an exobiology mission scheduled to launch in 2013. An advanced version of the instrument is currently under development. A new detector system with a higher energy resolution will not only reduce the necessary measurement time considerably, but also allow the simultaneous acquisition of an X-ray fluorescence spectrum to determine the elemental composition of samples.
Evidence for Ferrous Phosphates in Paso Robles Soils, Gusev Crater, Mars
Where: GSA Annual Meeting, Houston, Texas, USA Dates: 5th October 2008 - 9th October 2008 When: 5th October 2008
C. Schröder, E.M. Hausrath, D.C. Golden, D.W. Ming, R.V. Morris, and G. Klingelhöfer
Light-toned soil deposits have been churned up at Paso Robles by the Mars Exploration Rover Spirit's wheels during its ascent of Husband Hill in Gusev crater. These deposits are rich in sulfur and ferric sulfate, and were possibly formed by hydrothermal processes. They share a relatively high abundance of phosphorous with surrounding rocks. Up to 10 % phosphate mineral phases are expected to be present in Paso Robles soils. Calcium phosphates have been suggested but have not been confirmed by visible/near-infrared or thermal emission data. Evidence for ferric phosphates has been put forward. Because the light-toned Paso Robles soils were churned up from underneath a sand layer of basaltic composition, doublets arising from ferrous phases in the Mössbauer spectra obtained from two light-toned soil deposits at the Paso Robles location were initially assigned to silicates as a result of presumed physical mixing of the light-toned materials and the basaltic sand. Upon more detailed evaluation of the Mössbauer data, an alternative interpretation may be the presence of ferrous or mixed-valence phosphates such as vivianite or other members of the homologous series Fe2+3(PO4)2·n(H2O), including anhydrous phases. A reasonable scenario for the formation of ferrous phosphates and ferric sulfates would be for sulfuric acid to react with basalt containing apatite (or merrillite). In such a reaction the Ca-phosphate would form CaSO4 and phosphoric acid. The phosphoric and/or excess sulfuric acid would react with olivine, forming Fe2+ phosphate (e.g., vivianite) and sulfate (e.g., melanterite). The phosphate is less soluble and precipitates first. The ferrous sulfate remaining in solution could be oxidized as the pH of the solution increases. Rocks of the Wishstone class in the vicinity of Paso Robles, for example, contain olivine and Ca-phosphates, and represent possible parent material.
Where: 39th Lunar and Planetary Science Conference, League City, Texas Dates: 10th March 2008 - 14th March 2008 When: 11th March 2008
C. Schröder, K. Di, R.V. Morris, G. Klingelhöfer, R. Li, and the Athena Science Team
Where: International Conference on the Applications of the Mössbauer Effect (ICAME), Kanpur, India Dates: 14th October 2007 - 19th October 2007 When: 18th October 2007
Schröder, C., G. Klingelhöfer, R.V. Morris, D.S. Rodionov, I. Fleischer, and M. Blumers
A stony meteorite discovered by the Mars Exploration Rover Opportunity on Meridiani Planum, Mars
Where: 69th Annual Meeting of the Meteoritical Society, Zürich, Switzerland, The Meteoritical Society Dates: 6th August 2006 - 11th August 2006 When: 11th August 2006
C. Schröder, R. Gellert, B.L. Jolliff, G. Klingelhöfer, T.J. McCoy, R.V. Morris, D.S. Rodionov, P.A. de Souza Jr., A.S. Yen, J. Zipfel, and the Athena Science Team
Neue Ergebnisse der MER Mössbauer-Spektrometer
Where: DPG Frühjahrstagung, Heidelberg, Deutsche Physikalische Gesellschaft Dates: 13th March 2006 - 16th March 2006 When: 16th March 2006
C. Schröder, D. Rodionov, I. Fleischer, M.Blumers, J. Girones, J.F. Sanchez, M. Hahn, and G. Klingelhöfer
Die NASA Mars Exploration Rover Spirit und Opportunity führen seit über einem Mars-Jahr (670 sols, etwa 687 Erdtagen entsprechend) erfolgreich Untersuchungen der Oberfläche des Planeten durch. Spirit im Gusev-Krater hat in dieser Zeit den Gipfel des Husband Hill erklommen und befindet sich nun auf dem Abstieg. Auf dem Weg zum und vom Gipfel wurden dabei mit Hilfe des Mössbauer-Spektrometers neue Gesteinsarten identifiziert, die neues Licht auf die komplizierte Stratigraphie der Columbia Hills werfen. Opportunity hat auf seinem Weg über Meridiani Planum mittlerweile den Bereich der Landeellipse verlassen und befindet sich an der lithologischen Grenze zwischen dem sogenannten ’smooth terrain’ und dem ’etched terrain’. Während der Traverse wurde eine Anzahl von ’cobbles’, wahrscheinlich impakt-generierte Gesteinsbruchstücke, u.a. mit dem Mössbauer-Spektrometer analysiert. Die Mössbauer-Resultate zeigen, dass die ’cobbles’ von Bruchstücken möglicherweise meteoritischen Ursprungs über Bruchstücke des allgegenwärtigen Sedimentgesteins bis zu Bruchstücken basaltischer Zusammensetzung reichen, die möglicherweise von einer Schicht unterhalb des Sedimentgesteins stammen.
Diversity of Rocks in the Columbia Hills, Gusev Crater, Mars
Where: DMG Tagung 2005, Aachen, Deutsche Mineralogische Gesellschaft Dates: 18th September 2005 - 21st September 2005
C. Schröder, G. Klingelhöfer, R.V. Morris, D.W. Ming, D. Rodionov, and P.A. de Souza Jr.
Two miniaturized Mössbauer (MB) spectrometers are part of the payload of the twin Mars Exploration Rovers “Spirit” and “Opportunity” [1]. They determine the Fe-bearing mineralogy of rocks and soils. The plains surrounding Spirit’s landing site are covered by olivine-bearing basalts, evidence that physical rather than chemical weathering processes are currently dominant [2]. On sol 156 Spirit crossed the boundary from the plains into the Columbia Hills. The hills represent older terrain than the surrounding plains and are characterized by several distinct units of rocks. Rocks at “Hank’s Hollow” at the base of the hills have less olivine and are enriched in nanophase Fe-oxides and crystalline hematite compared to the plains basalts [3]. Outcrop material at “West Spur” further up the hills contain the Fe-oxyhydroxide goethite. At “Husband Hill”, even further up, are other rocks whose mineralogy points to chemical weathering. A bright-coloured soil component “Paso Robles” is dominated by a hydrous Fe-sulfate [4]. Rocks in the Columbia Hills are substantially more weathered than rocks in the surrounding plains. Water at low pH is the most likely weathering agent.
References: [1] Klingelhöfer et al. (2003), JGR 108, E12, 8067, [2] Morris et al. (2004), Science 305, 833-836, [3] Schröder et al. (2005), LPSC XXXVI, abstract # 2309, [4] Morris et al., submitted to JGR.
Where: 36th Lunar and Planetary Science Conference, League City, Texas Dates: 14th March 2005 - 18th March 2005
C. Schröder, G. Klingelhöfer, R.V. Morris, D.S. Rodionov, P.A. de Souza Jr., D.W. Ming, A.S. Yen, R. Gellert, J.F. Bell III, and the Athena Science Team
Mössbauer spectroscopy on Mars and its potential contribution in the search for extraterrestrial life
Where: 14th Annual Goldschmidt Conference, Copenhagen, Denmark, The Geochemical Society Dates: 5th June 2004 - 11th June 2004
C. Schröder, G. Klingelhöfer, R.V. Morris, B. Bernhardt, D. Rodionov, P.A. de Souza Jr., and F. Renz
For the first time in history a Mössbauer spectrometer was placed on the surface of another planet. The minaturized Mössbauer spectrometer MIMOS II, set up in backscattering geometry, is part of the payload of NASA’s twin Mars Exploration Rovers (MER) “Spirit” and “Opportunity”. They have measured the Fe-bearing mineralogy of several rocks and soil spots on two distinctly different landing sites, Gusev Crater and Meridiani Planum, spaced halfway across the planet. From orbital observations both landing sites have been associated with ancient water activity and are thus prime sites for the search for possible past or present life on Mars.
In this presentation we will compare several Mössbauer spectra obtained on the Martian surface with Mössbauer measurements performed in laboratories on Earth, using a copy of the flight instrument as well as conventional transmission Mössbauer spectrometer setups. Samples measured on Earth comprise in particular the SNC meteorites, including ALH84001.
We will explain what these data tell us about the evidence for the presence of water on both landing sites and evaluate the potential contribution of Mösbauer spectroscopy to the search for extraterrestrial life.
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