ARES - Astromaterials Research and Exploration Science

Volatiles in Extraterrestrial and Terrestrial Materials

Description: Studies of the abundances, distributions, and isotopic compositions of volatiles in lunar samples, meteorites, interplanetary dust particles, and terrestrial samples provide important information of the past thermal conditions and gaseous environments under which they were formed and have undergone subsequent modifications. Studies of the volatile elements (i.e., H, C, O, N, and S), abundances, and isotopic compositions in extraterrestrial materials help us understand the evolution of volatiles on other bodies in our solar system. Recent investigations have concentrated on the study of meteorites from Mars. Our work has shown the presence of possible biogenic activity within one of the oldest Martian meteorites. Research on the isotopic composition of oxygen (i.e., three isotopes) within components in the Martian meteorites reveals distinct oxygen reservoirs. Carbon isotopic compositions of carbon-bearing components within the Martian meteorites vary by over 100 per mil, suggesting a record of extreme carbon fractionation on Mars. We take isotopic measurements of the volatile elements within samples after we characterize materials with microscopic observations. These combined studies help us decode the unusual record of biogenic activity recorded within the Martian meteorite.
Investigations use the latest analytical equipment, including two stable isotope mass spectrometers, and laser microprobes interfaced to either mass spectrometers or gas chromatographs/computer systems. Other examples consist of (1) microfluorination-laser extraction techniques for the measurement of three isotopes of oxygen within silicate systems; (2) microthermometry for the study of fluid inclusions; and (3) analytical instrumentation to determine the identity of the volatiles released during heating and/or crushing and laser extraction, and to determine abundances, temperature-release ranges, isotopic compositions, and sequence of release. Analytical facilities are also available for the measurements of abundances, distributions, and isotopic compositions of a variety of terrestrial and extraterrestrial materials.

References: Romanek CS, et al: Nature 372: 655, 1994
McKay DS, et al: Science 273: 924, 1996

Soil Chemistry and Mineralogy

Description: A research program is underway to develop synthetic, inorganic highly reactive ´´soils´´ for plant growth experiments in microgravity. One particular system, ´´zeoponics´´, is the cultivation of plants in zeolite substrates that contain essential plant-growth cations on their exchange sites and have minor amounts of mineral phases (e.g., synthetic apatite) supplying essential plant growth anions. The exchange behavior (i.e., ion-exchange selectivities, kinetics of exchange) of zeoponics systems are being examined. In addition, plant growth experiments have been conducted to determine economics of plant production in zeoponics systems compared with other plant growth systems (e.g., hydroponics).
Other projects in soil chemistry and mineralogy are encouraged, especially clay mineralogy, zeolite chemistry and mineralogy, and mineral syntheses. Several studies are underway to determine the possible mineralogy and chemistry of Martian surface materials and the mineralogy of phyllosilicates in meteorites and interplanetary dust particles. Experimental and analytical facilities include x-ray diffraction, infrared spectroscopy, electron microscopy (e.g., scanning transmission electron microscopy, scanning electron microscopy, and electron microprobe), and atomic absorption spectroscopy.

References: Allen ER, et al: Agronomy Journal 87: 1052, 1995
Golden DC, et al: Meteorites 30: 418, 1995

Mineralogy of Fine-Grained Extraterrestrial Materials

Description: The early history of the solar system is being explored through detailed characterization of the minerals and noncrystalline phases composing primitive extraterrestrial materials. As these materials are typically very fine grained, this research is being performed principally by analytical electron microscopy, high-resolution transmission electron microscopy, and x-ray microdiffraction, as complemented by standard petrographic and electron-beam techniques. We are currently examining carbonaceous chondrites, as well as interplanetary dust particles (IDP) collected from the stratosphere and from Greenland and Antarctic Ice. Of particular interest are IDPs with refractory mineralogies, which potentially contain very primitive nebula condensates and/or presolar materials and the record of low-temperature planetary alteration processes, as revealed by the paragenesis of the matrix phases within carbonaceous chondrites. We are also developing particle collectors for the Stardust Discovery Mission to Comet Wilde Z and are characterizing collection surfaces flown on the Long Duration Exposure Facility, Eureca, and Mir.

References: Zolensky ME, et al (eds): Analysis of Interplanetary Dust. New York: American Institute of Physics, 1994

Isotopic Studies of Primitive Materials

Description: Isotopic and elemental studies of extraterrestrial materials are performed at submicrometer scales by NanoSIMS 50L ion microprobe. Current research focuses on the characterization of circumstellar and interstellar grains, and molecular cloud matter. Isotopic compositions are used to constrain models of stellar nucleosynthesis, galactic chemical evolution, the histories of interstellar grains in the galaxy, and chemical processes in the interstellar medium and early solar system.

References: Messenger SR, et al: Science 300: 205, 2003
Keller LP, Messenger SR, et al: Geochimica et Cosmochimica Acta 68: 2577, 2004

Isotopic and Chemical Studies of the Evolution of Solid Objects in the Solar System

Description: Laboratory analyses of lunar, meteoritic, and terrestrial samples are conducted to provide isotopic, chronological, and chemical constraints for the evolution of solid objects in the solar system.
Current emphasis centers on lunar sample and meteorite analysis. Research on related terrestrial evolutionary analogs will also be considered. Facilities include clean laboratories for physical and chemical preparation of samples and two automated thermal-emission mass spectrometers for sample analysis. One of these is a multisample, seven-collector, late-generation instrument. The laboratory`s lunar sample analysis program emphasizes the geochemical evolution of lunar mare basalts and highland rocks as recorded in their isotopic systematics. The meteorite analysis program applies isotopic constraints to the chronology and petrogenesis of basaltic meteorites, the formation of the solar system, and to stellar nucleosynthesis. Research which emphasizes laboratory or theoretical investigations of lunar-basalt genesis, genesis of basaltic rocks on other planetary objects, or categorization and interpretation of nucleosynthetic components in primitive meteorites is especially appropriate for our program. Research that focuses on planetary crustal development is also appropriate, as are studies that seek to unravel the cratering history of planetary surfaces or the history of meteorites in space by measuring cosmic ray-produced nuclides.

Experimental Investigations of Planetary Processes

Description: Experiments delineating the geochemical behaviors of chemical elements during planetary processes are important for understanding the elemental abundance patterns that are observed in planetary materials. Specifically, geochemical behaviors of elements change with temperature (T), pressure (P), oxygen fugacity (f02), and bulk chemical composition of the system (SCi). Laboratory experiments are performed to better understand the detailed geochemical behaviors of trace elements in planetary processes such as core formation and basalt genesis. The results of these studies are then used to understand the origin of meteorites, the Earth, and the Moon. Because the conditions that pertained during laboratory experiments are seldom identical to those occurring in nature, it is also important to have means of extrapolating laboratory results to different (P,T,f02, SCi) conditions. Thus, our research objectives are (1) to determine the geochemical behaviors of elements in the laboratory, (2) to use these experiments and standard thermodynamic techniques to extrapolate from the laboratory to natural systems, and (3) to use the extrapolated experimental data to constrain the nature of planetary processes.

Siderophile Element and Isotope Investigations of Meteorites and Terrestrial Planets

Description: Siderophile element concentrations in metal and stony fractions of planets and meteorites are a record of processes acting during formation of the solar system, and for differentiation and evolution of solid objects. The radiogenic Re-Os and Hf-W geochronometers provide time constraints for solar system processes that led to fractionation between the parent and daughter elements in these two systems. Our isotope geochemistry laboratory has the capability to perform chemical separation procedures for purifying siderophile elements from meteorites, lunar rocks, and terrestrial samples for analysis. We have recently taken delivery of a new thermal ionization mass spectrometer with negative ion capability for the precise isotopic measurement of Os and W. Thus, opportunities exist to investigate nebular and planetary processes combining these isotopic data with siderophile element concentration data. Projects currently underway address the timing of accretion; core formation; and early differentiation in asteroids, Mars, Moon, and Earth; fractionation of highly siderophile elements in planetary systems; the origin of metal grains in chondrites; and the partitioning of siderophile elements in metal phases, oxides, sulfides, and silicates through measurement of natural materials.

Petrology and Geochemistry of Meteorites from Mars and the Asteroids, and Terrestrial Analogs

Description: Martian meteorites are the only samples currently available for the study of the petrologic evolution of Mars. Most other meteorites are fragments of asteroids ranging from primitive bodies, to magmatically differentiated bodies. Some terrestrial igneous rocks, both volcanic and plutonic, are close analogs to martian meteorites and some of the igneous asteroidal meteorites. Studies of these three types of materials may lead to a broader understanding of formation of the solar system and planetary differentiation. Major and trace-element analyses by instrumental neutron activation analysis are coupled with petrologic studies using the electron microprobe of the meteorites in order to evaluate their origins. Studies of terrestrial analogs to martian and meteoritic igneous rocks are valuable in constraining the processes of igneous differentiation on other bodies in the solar system.

References: Mittlefehldt D.W. Meteoritics & Planetary Science 40: 665, 2005.
Mittlefehldt D.W. and Lindstrom M.M. Geochimica et Cosmochimica Acta 67: 1911, 2003.
Mittlefehldt D.W. et al. Meteoritics & Planetary Science 37: 345, 2002.

Experimental Trace-Element Partitioning and Petrogenesis of Extraterrestrial Igneous Rock

Description: One very important approach to deciphering geologic history is through the study of trace-element abundances in rocks. Reliable interpretation of such abundance data requires knowledge of the effects of geological processes on trace-element abundances. In order to contribute to this knowledge, we are studying the partitioning of various trace elements between silicate melts and several geologically important minerals in controlled laboratory experiments. Effects of mineral and melt composition are being systematically investigated. Emphasis has been placed on minerals and liquid compositions believed to have played an important role in the geochemical evolution of the lunar crust and mantle, in petrogenesis of Martian meteorites, and in the petrogenesis of the very primitive angrite meteorites. However, studies of other compositional systems having relevance to planetary science are also encouraged. Equipment includes numerous one-atmosphere, gas-mixing furnaces capable of reaching 1,500oC internally and externally heated pressure vessels covering conditions to 10 kbars and 1,200oC, a piston-cylinder apparatus covering conditions to 30 kbars, and a controlled-atmospheric thermogravimetric-analysis system capable of reaching 1,300oC. Electron microprobe and electron microscope facilities are also available.

References: McKay GA, et al: Geochimica et Cosmochimica Acta 58: 2911, 1994

Noble-Gas Isotopic Abundances in Planetary Materials

Description: Isotopic abundance determinations of the noble-gas elements (He, Ne, Ar, Kr, and Xe) in meteorites and lunar samples furnish important information on a variety of planetary problems. Some problems recently addressed by our laboratory include (1) the isotopic composition and origin of various volatile components in the solar system, including the atmospheres of Mars and other planets, solar wind species implanted into the lunar regolith, and ancient energetic solar emissions; (2) the 39Ar-40Ar chronology of the formation and metamorphism of various meteorite types, including Martian meteorites, and of the early lunar crust; and (3) the history of collisional breakup events among meteorite parent bodies and the ages of lunar surface features using noble gases produced by energetic cosmic ray protons and by 39Ar-40Ar dating. Most types of isotopic measurements of noble gases are possible, including those on irradiated samples. Available equipment includes two high-sensitivity noble gas mass spectrometers with computer control, low-blank induction-heated furnaces equipped with thermocouples, an infrared laser equipped with a focusing and imaging system, a gas calibration system, and low-blank vacuum systems.

References: Bogard DD: Meteoritics 30: 244, 1995
Rao MN, et al: Meteoritics and Planetary Science 32: 531, 1997

Physicochemical State of the Martian Surface

Description: The general objective of this continuing research program is to understand the nature and constitution of surficial material on Mars and to determine the weathering processes that evolved the surface to its current state. Specific tasks include (1) studies of geologic samples that have been weathered in terrestrial environments considered to be analogous in some important respects to those on Mars, (2) theoretical and experimental studies of the optical properties of pure and substituted iron-bearing compounds, and (3) instrument development. Emphasis is placed on multidisciplinary analyses of samples to maximize comparison with the data base available for Mars from the Viking, Phobos-2, and Mars Pathfinder missions and telescopic observations. Experimental and analytical facilities include ferromagnetic resonance spectroscopy, vibrating sample magnetometer, Mössbauer spectroscopy, and ultraviolet-visible-infrared spectroscopy. Instrument development includes a backscatter Mössbauer spectrometer for planetary applications.

References: Morris RV, et al: Mineral Spectroscopy, Geochemistry Society Special Publication 5: 327, 1996
Morris RV, et al: Journal of Geophysical Research 102: 9125, 1997

Analytical Studies of Space Weathering Effects on Lunar and Asteroid Surfaces

Description: A long-term program is underway to analyze and interpret many of the characteristics of lunar soils, cores, and regolith breccias. Lunar soils have formed by complex processes including impacts, solar wind implantation and radiation effects, and volcanic processes which were active in earlier lunar history. Ancient lunar soils are preserved in some regolith breccias and in some of the returned core material. A challenging research task is to decode the record in these ancient regoliths using clues from current ones, and to determine something about the meteorite flux; meteorite composition; solar wind, flare, and early volcanic activity; and general lunar evolution over the course of lunar geologic history. A major objective is to quantify the physical, chemical, and optical effects of space ´´weathering´´ on exposed lunar soils and possible asteroid regolith material (interplanetary dust particles). Research techniques include optical and scanning electron microscopy petrographic analysis; electron microprobe analysis; scanning electron microscopy studies of grain surfaces and textures; transmission electron microscopy studies of textures including radiation and shock damage; quantitative analysis of grain sizes, grain shapes, and surface features; and population studies of mineral and glass phases. Experience in petrology, scanning electron microscope analysis, transmission electron microscope analysis (including high-resolution work), image analysis, and geochemistry would be useful for this project.

Characterization of the Resource Potential of Lunar Regolith

Description: Lunar regolith contains rock, mineral, and glass grains of all sizes from cm down to submicrometer. Future robotic and human missions to the Moon will require such useful materials as oxygen extracted from oxides and silicates; solar wind implanted gases such as hydrogen, nitrogen, and carbon dioxide; and metals such as titanium, aluminum, or iron refined from rocks or soil. Research focuses on the detailed state of useful materials in unprocessed regolith. The results of this research will influence the nature of systems designed to extract the useful materials. Emphasis is placed on the state and location of implanted hydrogen, the kinetics of solid-state diffusion of these gases in lunar materials, the degree of natural reduction of oxides and silicates in lunar soils and rocks, and the amount and nature of reduced iron and other metals. Such data will add to our understanding of both the evolution of the lunar regolith and the natural processes that reduce lunar soils, which will also influence the design of chemical systems to accomplish the same thing artificially. Research techniques will include optical and analytical electron microscopes, high-resolution electromagnetic imaging, scanning electron microscopy studies of grain surfaces and textures, and studies of radiation damage as a function of depth within soil grains. We may also conduct additional laboratory experiments in controlled fugacity gas-mixing furnaces to help duplicate and understand the features found in the lunar materials. Experience in chemistry, petrology, electron microscopy, solid-state physics, experimental petrology, or optical spectroscopy would be useful for these studies.

Investigations of Natural and Experimental Hypervelocity Impacts

Description: We pursue hypervelocity meteorite impact as a geological process to learn about the accretion, differentiation, and the evolution of current, heavily cratered surfaces of planets and their moons, including the collisional evolution of small solar system objects. Our largely experimental approach uses powder propellant and light gas gun facilities to launch a variety of projectiles into geologic solids at velocities as high as 7 km/s. Postmortem analysis of these laboratory impacts may range from cratering mechanics to the shock-induced modifications of minerals and rocks. These experimental studies are partially complemented by the analysis of naturally shocked materials, field studies of terrestrial impact structures, and theoretical considerations. We are interested in the velocity distribution of crater ejecta and collisional fragmentation products, the evolution of asteroidal regoliths and meteoritic breccias, and the shock metamorphism of carbonates. Additional efforts focus on the development of aerogel as a suitable capture medium for hypervelocity projectiles in support of STARDUST, a Discovery-Class comet fly-by mission. Such capture media are also being exposed on the MIR Station to trap both natural cosmic dust and man-made orbital debris; these collectors were retrieved in September 1997 for post-flight analysis.

References: Hörz F, Cintala MJ: Meteoritics and Planetary Science 32: 179, 1997
Bernhard RP, Hörz F: International Journal of Impact Engineering 17: 69, 1995

Planetary Impact Processes

Description: Impact is the only major geological process common to all of the solid bodies of the Solar System. As a result of this single pervasive mechanism, craters and regoliths are formed on the planetary-scale objects, asteroids and satellites are disrupted, and particles are supplied to the interplanetary dust complex. Many aspects of impact cratering and collisional disruption fall within the purview of the Experimental Impact Laboratory.
Although such experiments can be performed with either of the other two guns in the laboratory, cratering and collisional-disruption experiments are primarily conducted with a vertical gun. Projectiles of various compositions ranging between 3 and 20 mm in diameter can be launched at velocities of hundreds of meters to nearly 3 km/s. In addition, target materials can be varied as dictated by experimental objectives; a refrigerated target chamber permits the use of ice and other low-temperature targets.
Recent investigations have included disruption of various rock and ice targets, the physical and chemical evolution of ´´experimental regoliths´´, measurement of ejection velocities, and the chemistry and petrography of agglutinate-like particles created during the regolith-evolution experiments. Theoretical and observational studies of these processes are encouraged.

Orbital Debris Hazard Assessment

Description: NASA Johnson Space Center has a program to better understand the character of the man-made orbital debris environment, the implications of this environment on the design and operations of spacecraft, and the development of national and international standards to minimize the future orbital debris environment.
This program consists of four major components: (1) modeling of the environment; (2) measurements of the environment; (3) hypervelocity impact testing to determine the consequences of the environment and the design of shielding; and (4) consulting with industry, other government agencies, and other space-faring nations for making cost-effective recommendations to minimize the hazard to future spacecraft.
Predictions of the flux resulting from the orbital debris environment are made from both source and sink models, which include spacecraft traffic models, satellite breakup models, and atmospheric drag models. We test these predictions against environmental measurements. Such measurements include the relatively large (>10 cm) objects maintained in the US Space Command catalog, intermediate sized (1 mm to 10 cm) that are sampled by ground telescopes and high-frequency ground radars, and small objects (<1 mm) that are sampled through hypervelocity impacts on recovered spacecraft surfaces. JSC obtains data using a three meter liquid mirror telescope and the Haystack radar, maintains samples from several recovered satellite surfaces, and maintains laboratories to measure the characteristics and chemistry of impact craters. To date, the measurements program has identified sources of orbital debris that were not included in the models.
The probability that a spacecraft will fail to function because of an orbital debris or meteoroid impact can be reduced with specially designed shielding. JSC maintains three hypervelocity guns, and has played a critical role in designing shields for the planned Space Station. In an effort to minimize the shielding weight of the Shuttle and Space Station, hypervelocity (velocities greater than 5 km/sec) tests are conducted on various spacecraft materials and configurations.
JSC has prepared a NASA safety standard, which includes guidelines and procedures for limiting orbital debris. We also conduct regular meetings with other US agencies and the ´´Inter-Agency Space Debris Coordination Committee´´ (with members from the US, Europe, Russia, and Japan). The purpose of these meetings is to coordinate research and reach a common consensus for the international standards of limiting orbital debris.

Crystallization Studies

Description: The dynamic crystallization of rock and mineral melts in the laboratory under controlled conditions makes it possible to study such features as rock textures, mineral zoning, element partitioning, nucleation, and the effects of co-precipitation of minerals, fractional crystallization, and differentiation as a function of crystallization conditions. By experimentally replicating the mineral assemblages and textures of natural materials in synthetic equivalents and by determining the stability of minerals, it is possible to formulate the sets of conditions appropriate for the origin and evolution of planetary crustal and meteoritic materials. Current emphasis is placed on the origin of chondrules in the nebula. The equipment available includes internally and externally heated pressure vessels covering the experimental conditions ranging up to 10 kbars and 1,200oC, one-atmosphere, gas-mixing furnaces with direct monitoring of oxygen fugacities and a piston cylinder for high-pressure experiments to 40 kbars.

References: Lofgren GE: in Chondrules and the Proto Planetary Disc. Cambridge: Cambridge University Press, 1996: 187

Remote Sensing of Earth's Biomes

Description: The imagery from Space Shuttle cameras and other unmanned satellites is used to model the ecological changes occurring in the Earth`s biota. Current efforts include mapping and monitoring biomass burning in the global tropics to model the contributions of this phenomena to greenhouse gases. Other episodic events such as Kuwaiti oil fires are also analyzed to determine the dynamic nature of these biomass-atmosphere interactions. Emphasis is placed on the role of remote sensing from the Space Shuttle and Space Station sensors for global change research.