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An Astrobiology Strategy for the Exploration of Mars B Glossary Alkanes—Saturated hydrocarbons having the general formula CnH2n+2, where n is an integer >0. Examples include methane (CH4) and propane (C4H10). Amazonian—The geological epoch on Mars dating from some 3 billion years ago to the present day. Regions formed in this period have relatively few impact craters. APXS—Alpha Proton X-ray Spectrometer. ASTEP—Astrobiology Science and Technology for Exploring Planets. ASTID—Astrobiology Science and Technology Instrument Development. Astrobiology Field Laboratory (AFL)—NASA’s proposed fourth-generation Mars rover (following on from Mars Pathfinder’s Soujourner, the Mars Exploration Rovers Spirit and Opportunity, and the Mars Science Laboratory). As currently conceived, this rover is a candidate for launch in 2016 or 2018. It will be broadly similar in mass, size, and payload capacity to the Mars Science Laboratory. But it will be equipped with a different set of scientific instruments, possibly ones focusing on life detection. BIF—Banded iron formation, 2 billion- to 3.5 billion-year-old banded rock consisting largely of chert and iron minerals. Biosignatures—A variety of indicators (e.g., chemical, morphological, mineralogical, isotopic) that support the possible existence of past life. Carbonaceous chondrite—A type of stony meteorite that is rich in carbon compounds and is thought to be relatively unaltered since the beginning of the solar system. The bulk elemental composition of these chondrites is believed to resemble that of the material from which the solar system formed. ChemCam—An instrument under development for the Mars Science Laboratory. It utilizes a laser system for spectroscopic analysis and microimaging. Chemolithoautotrophs—Organisms deriving all of their carbon and energy requirements from inorganic compounds. Chiral—Describing a molecule configured such that it cannot be superimposed on its mirror image. CHNOPS—Carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur; the most important biogenic elements. COEL—Committee on the Origins and Evolution of Life. CRB—Columbia River Basalt.
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An Astrobiology Strategy for the Exploration of Mars Diastereoisomers—Stereoisomers that are not mirror images of each other. Electrophoresis—A chemical analysis technique that takes advantage of the differential movement of a charged substance under the influence of an electric field. Enantiomers—Stereoisomers that are mirror images of each other. Enantiomers are optically active and rotate the plane of polarized light. Epimer—A stereoisomer that has a different configuration at only one of several chiral carbon centers. Extremophiles—Microorganisms capable of growing under extreme physiochemical conditions, such as high temperatures, pressures, and acidity. Fischer-Tropsch (FT) process—A method for the synthesis of hydrocarbons and other carbon compounds. Typically, a mixture of hydrogen and carbon monoxide is reacted in the presence of an iron or cobalt catalyst to produce methane and other organic compounds, with water and carbon dioxide as by-products. GC-MS—Gas chromatography-mass spectrometry. Graben—A block of the crust, generally with length much greater than its width, that has dropped relative to the areas on either side because it is bordered by two faults. GRS—Gamma-Ray Spectrometer. HEND—High-Energy Neutron Spectrometer. Hesperian—The martian geological epoch ranging from some 3.7 billion to 3 billion years ago. Regions that were formed in this era are characterized by extensive lava fields. Isomer—One of two or more substances that have the same chemical composition but differ in structural form. Kerogens—A family of chemical compounds that make up a portion of the organic matter found in sedimentary rocks. They are insoluble in organic solvents, non-oxidizing acids (HCI and HF), and bases because of their very high molecular weight. Each kerogen molecule is formed by the random combination of numerous monomers. When heated, hydrogen-rich kerogens yield crude oil, and hydrogen-poor kerogens yield mainly gas. Labile—Easily reactive. LC-MS—Liquid chromatography-mass spectrometry. Macromolecules—Molecules with a high molecular mass, such as polymers. Mars Express—A European Space Agency mission comprising an obiter mapping the surface and atmospheric composition and an unsuccessful lander, the Beagle 2. Mars Express has been orbiting Mars since late 2003. Mars Odyssey—A NASA spacecraft launched in 2001. Odyssey is an orbiter looking for evidence of past or present water and mapping the mineralogical characteristics of the martian surface. MAVEN—The Mars Atmosphere and Volatile Evolution mission, one of two candidates under consideration by NASA for the Mars Scout launch opportunity in 2011. MEPAG—NASA’s Mars Exploration Program Analysis Group. MER—NASA’s Mars Exploration Rover mission, which launched two rovers, Spirit and Opportunity, in 2003. Both rovers are equipped to image and analyze the martian landscape. Metazoa—Multicellular organisms capable of locomotion. Metaphytes—Multicellular plants. MGS—NASA’s Mars Global Surveyor spacecraft, which has been orbiting Mars since 1996. Although the spacecraft completed its primary mission of mapping the martian surface in 2001, it continued to return important scientific data until it lost contact with Earth in November 2006. Mid Rovers—A proposed Mars rover mission currently being studied as a candidate for launch in 2016 or 2018.
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An Astrobiology Strategy for the Exploration of Mars These rovers are currently conceived as being more capable than the Mars Exploration Rovers but less complex, costly, and heavy than the Mars Science Laboratory. Miller-Urey Experiment—The 1953 experiment testing the possibility of constructing organic compounds using a spark of electricity and inorganic molecules such as water, methane, ammonia, and hydrogen. The experiment showed that it is possible to form some of the building blocks of life without life present to synthesize them. MRO—A NASA spacecraft launched to Mars in 2005. It began relaying high-resolution images and other scientific data in 2006. It is currently laying the groundwork for future missions by analyzing weather, surface conditions, landforms, ice, and possible landing sites. MSL—Mars Science Laboratory, a NASA mission scheduled for launch in 2009. MSL is a rover significantly larger than the Mars Exploration Rovers and capable of carrying a comprehensive payload of advanced scientific instruments. MSTO—Mars Science and Telecommunications Orbiter, a proposed NASA mission currently scheduled for launch in 2013. Its primary goals are to study the martian atmosphere and climate and to provide communications infrastructure to future missions. NADPH—The reduced form of nicotinamide adenine dinucleotide phosphate Noachian—The earliest identified martian geological epoch. It spans the period from some 4.1 billion to 3.7 billion years ago. Regions from this epoc are heavily marked with impact craters. These regions were subject to extensive flooding by liquid water late in the period. NS—Neutron spectrometer. Nuées ardentes—Clouds of incandescent, gas-charged ash that flow down the sides of an erupting volcano at high speeds. Obliquity—The angle between the orbital plane of an object and its equatorial plane. OMEGA—The visible and infrared mineralogical mapping spectrometer on the Mars Express. Phoenix—A NASA Mars lander mission scheduled for launch in 2007. Phoenix will look for evidence of water and possible habitats for microbial life on Mars. Photolysis—The decomposition of a chemical substance into simpler units as a result of the action of light. Phyllosilicates—A family of minerals featuring parallel sheets of silicate. Examples include clays, mica, and serpentine. Pinpoint landing—Generally speaking, the landing of a spacecraft on a planet’s surface within a few hundred meters of a pre-selected point. Polycyclic aromatic hydrocarbons (PAHs)—A class of very stable organic molecules made up of only carbon and hydrogen. These molecules are flat, with each carbon having three neighboring atoms, much like graphite. They are a standard product of combustion. Precision landing—Generally speaking, the landing of a spacecraft on a planet’s surface within 10 km or so of a pre-selected point. Psychrophiles—Organisms that have a maximum growth temperature of 20°C, an optimal growth temperature of 15°C or lower, and a minimum growth temperature of 0°C or lower. Pyrolysis—The breakdown or destruction of a molecule caused by heat. R&A—Research and analysis. Racemic compound, racemic mixture, racemate—An equimolar mixture of the two enantiomeric isomers of a compound. As a consequence of the equal numbers of levo- and dextro-rotatory molecules present in a racemate, there is no net rotation of the plane of polarized light. Radiolysis—The breakdown of a molecule as a result of ionizing radiation. Raman spectroscopy—A technique for determining the composition a material by measuring the change in energy of light scattered off the material. Regolith—The layer of fragmented, incoherent rocky debris on the surface of a planetary body.
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An Astrobiology Strategy for the Exploration of Mars Respiration—The process by which the chemical bonds of energy-rich molecules such as glucose are converted into energy usable for biological processes. Serpentinization—A metamorphic process in which ultrabasic rocks react with water to create a variety of hydrous, magnesium-iron phyllosilicate minerals known collectively as serpentine. The process is endothermic and results in the liberation of hydrogen, methane, and hydrogen sulfide. SLiME—Subsurface lithoautotrophic microbial ecosystem. SNC meteorites—The family of shergottite, nakhlite, and chassignite stony meteorites believed to have originated on Mars. SRB—Sulfate-reducing bacteria. Stereoisomers—Isomers that differ only in the arrangement of their atoms in space. Stratigraphic horizon—A layer within a planet’s crust that formed in a specific geological epoch. Strecker synthesis—The synthesis of -amino acids by the reaction of an aldehyde or ketone with a mixture of ammonium chloride and sodium cyanide followed by acid hydrolysis of the amino nitriles formed. Stromatolites—Lithified sedimentary growth structures formed by the trapping of sedimentary grains by microorganisms. Tholins—Complex polymeric substances formed on the surfaces of the icy bodies of the outer solar system by the irradiation of organic compounds. The arrival of these compounds on comets could provide the basic building blocks of life. TRL—Technology readiness level, a measure of the technical maturity of an instrument or mechanism. The higher the TRL, the more mature the technology.
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