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NASA NTRSDate not supplied

Mantle Source Mineralogy Inferred from Incompatible Element Ratios in Shergottites

The mineralogy of the martian mantle is a poorly known but vital compositional parameter. In the absence of samples of martian mantle peridotites, the mineralogy has been inferred from bulk composition constrained by a mix of cosmochemical and martian meteoritic constraints. Such a mineralogy reflects the primordial mantle composition, but mantle source regions that differentiated from a magma ocean are not likely to have the same mineralogy as bulk silicate Mars. An alternative approach is to infer source mineralogy of the martian mantle from the analysis of incompatible elements in shergottites. In a recent study, we showed that the general compatibility order of trace lithophile elements in martian mantle is similar to that of MORB mantle, with some exceptions. Compared to MORB mantle, in martian mantle: (1) highly incompatible elements (Th, Nb, Ta and U) are less incompatible relative to La; (2) K is significantly more compatible with respect to other elements; and (3) the HREEs are more compatible. In this study, we calculated effective partition coefficients of trace elements directly from martian igneous meteorites and used this data to infer the source mineralogy of the martian mantle.

Mars↗
NASA NTRS1993

Evidence for an ice sheet/frozen lake in Utopia Planitia, Mars

Previous workers noted evidence for a lacustrine basin in Utopia Planitia, Mars. Geomorphic features within the basin that collectively suggest that water or ice may once have been present include channels within the basin, channels peripheral to the basin, etched basin floor, 'thumbprint' terrain (whorled patterns), polygonal outlines, smooth floors (infilled), shoreline indicators (terraces, platforms, lineaments), and small cratered cones (pseudo craters or pingos). The authors interpret these data to suggest that the basin may have been the locus of a large paleolake in the northern lowlands of Mars. Alternatively, the area was proposed to be part of an ancient circumpolar ocean. The hypothetical paleolake was probably frozen to some depth. In fact, features now present at its boundaries suggest that the edges may have been frozen solid. Plains units at the southwestern boundary of Utopia Planitia show ridges that were compared with those that form at the mouths of Antarctic ice streams, thumbprint terrain, and young, high deposits having lobate margins that suggest mudflows. Thumbprint terrains were interpreted as recessional moraines, ice-pushed ridges, or subglacially eroded tunnel valleys with eroded eskers. At the east boundary of Utopia Planitia, geologic mapping at 1:500,000 scale of the Granicus Valles area (MTM quadrangles 30227, 30222, and 25227) indicates the presence of a basal scarp around the northwest flank of Elysium that formed the east boundary of an ancient ice sheet.

Chapman, M. G.↗
NASA NTRS2009

Timing of Crystallisation of the Lunar Magma Ocean Constrained by the Oldest Zircon

The presently favoured concept for the early evolution of the Moon involves consolidation of debris from a giant impact of a Mars sized body with Earth forming a primitive Moon with a thick global layer of melt referred to as the Lunar Magma Ocean1 . It is widely accepted that many significant features observed on the Moon today are the result of crystallisation of this magma ocean. However, controversy exists over the precise timing and duration of the crystallisation process. Resolution of this problem depends on the establishment of precise and robust key crystallisation time points. We report a 4417 6 Myr old zircon in lunar breccia sample 72215,195, which provides a precisely determined younger limit for the solidification of the Lunar Magma Ocean. A model based on these data, together with the age of the Moon forming giant impact, defines an exponential time frame for crystallisation and suggests formation of anorthositic crust after about 80-85% of the magma ocean was solidified. In combination with other zircon ages the 4417 +/- 6 Myr age also suggests that the very small (less than a few per cent) residual portion of the magma ocean continued to solidify during the following 300-500 m.y.

Nemchin, A.↗
NASA NTRS1993

The thermodynamic case for a water-rich Mars

The geologic evidence for a water-rich Mars has been reviewed, and it has been concluded that it is consistent with an outgassed inventory of H2O equivalent to global ocean 0.5-1 km deep. The most persuasive support for this conclusion comes from the martian outflow channels, whose distribution, size, and range of ages, suggests that a significant body of ground water was present on Mars throughout much of its geologic history. In this abstract, the thermodynamic implications of the outflow channels are considered. The results of this analysis suggest that if the outflow channels were carved by the discharge of ground water in diffusive and thermodynamic equilibrium with the overlying frozen crust, it implies a minimum planetary inventory of water in excess of 300 m. However, if the global inventory of ground water on Mars at the time of outflow channel formation was as high as the 500 m estimate of other researchers, then the total inventory of water on Mars could well exceed 750 m.

Clifford, Stephen M.↗
NASA NTRS2013

HERRO Mission to Mars Using Telerobotic Surface Exploration from Orbit

This paper presents a concept for a human mission to Mars orbit that features direct robotic exploration of the planet s surface via teleoperation from orbit. This mission is a good example of Human Exploration using Real-time Robotic Operations (HERRO), an exploration strategy that refrains from sending humans to the surfaces of planets with large gravity wells. HERRO avoids the need for complex and expensive man-rated lander/ascent vehicles and surface systems. Additionally, the humans are close enough to the surface to effectively eliminate the two-way communication latency that constrains typical robotic space missions, thus allowing real-time command and control of surface operations and experiments by the crew. Through use of state-of-the-art telecommunications and robotics, HERRO provides the cognitive and decision-making advantages of having humans at the site of study for only a fraction of the cost of conventional human surface missions. It is very similar to how oceanographers and oil companies use telerobotic submersibles to work in inaccessible areas of the ocean, and represents a more expedient, near-term step prior to landing humans on Mars and other large planetary bodies. Results suggest that a single HERRO mission with six crew members could achieve the same exploratory and scientific return as three conventional crewed missions to the Mars surface.

Oleson, Steven R.↗
NASA NTRS2002

Ultramafic Terranes and Associated Springs as Analogs for Mars and Early Earth

Putative extinct or extant Martian organisms, like their terrestrial counterparts, must adopt metabolic strategies based on the environments in which they live. In order for organisms to derive metabolic energy from the natural environment (Martian or terrestrial), a state of thermodynamic disequilibrium must exist. The most widespread environment of chemical disequilibrium on present-day Earth results from the interaction of mafic rocks of the ocean crust with liquid water. Such environments were even more pervasive and important on the Archean Earth due to increased geothermal heat flow and the absence of widespread continental crust formation. The composition of the lower crust and upper mantle of the Earth is essentially the-same as that of Mars, and the early histories of these two planets are similar. It follows that a knowledge of the mineralogy, water-rock chemistry and microbial ecology of Earth's oceanic crust could be of great value in devising a search strategy for evidence of past or present life on Mars. In some tectonic regimes, cross-sections of lower oceanic crust and upper mantle are exposed on land as so-called "ophiolite suites." Such is the case in the state of California (USA) as a result of its location adjacent to active plate margins. These mafic and ultramafic rocks contain numerous springs that offer an easily accessible field laboratory for studying water/rock interactions and the microbial communities that are supported by the resulting geochemical energy. A preliminary screen of Archaean biodiversity was conducted in a cold spring located in a presently serpentinizing ultramafic terrane. PCR and phylogenetic analysis of partial 16s rRNA, sequences were performed on water and sediment samples. Archaea of recent phylogenetic origin were detected with sequences nearly identical to those of organisms living in ultra-high pH lakes of Africa.

Blake, David↗
NASA NTRS1990

Smaller solar system bodies and orbits; Proceedings of Symposium 3, Workshops II, III, and XXVI, and Topical Meetings of the 27th COSPAR Plenary Meeting, Espoo, Finland, July 18-29, 1988

Topics discussed in this volume include the reappraisal of the moon and Mars/Phobos/Deimos; the origin and evolution of planetary and satellite systems; asteroids, comets, and dust (a post-IRAS perspective); satellite dynamics; future planetary missions; and orbital debris. Papers are presented on a comparison of the chemistry of moon and Mars, the use of a mobile surface radar to study the atmosphere and ionosphere, and laser-ionization studies with the technical models of the LIMA-D/Phobos. Attention is given to planetogonic scenarios and the evolution of relatively mass-rich preplanetary disks, the kinetic behavior of planetesimals revolving around the sun, the planetary evolution of Mars, and pre- and post-IRAS asteroid taxonomies. Consideration is also given to ocean tides and tectonic plate motions in high-precision orbit determination, the satellite altimeter calibration techniques, a theory of the motion of an artificial satellite in the earth atmosphere, ESA plans for planetary exploration, and the detection of earth orbiting objects by IRAS.

Runcorn, S. K.↗
NASA NTRS1994

The global climate of December 1992-February 1993. Part 2: Large-scale variability across the tropical western Pacific during TOGA COARE

Recently, scientists from more than a dozen countries carried out the field phase of a project called the Coupled-Atmosphere Response Experiment (COARE), devoted to describing the ocean-atmosphere system of the western Pacific near-equatorial warm pool. The project was conceived, organized, and funded under the auspices of the International Tropical Ocean Global Atmosphere (TOGA) Program. Although COARE consisted of several field phases, including a year-long atmospheric enhanced monitoring period (1 July 1992 -- 30 June 1993), the heart of COARE was its four-month Intensive Observation Period (IOP) extending from 1 Nov. 1992 through 28 Feb. 1993. An overview of large-scale variability during COARE is presented. The weather and climate observed in the IOP is placed into context with regard to large-scale, low-frequency fluctuations of the ocean-atmosphere system. Aspects of tropical variability beginning in Aug. 1992 and extending through Mar. 1993, with some sounding data for Apr. 1993 are considered. Variability over the large-scale sounding array (LSA) and the intensive flux array (IFA) is emphasized.

Gutzler, D. S.↗
NASA NTRS2017

Scientific and Technological Approaches to Searching for Extant Life in the Solar System

Future directions for investigations and measurements identified in the decadal survey Vision and Voyages for Planetary Science in the Decade 2013-2022 include direct methods to search for extant life. Within the framework a 35-year science vision for future decades extending into the 2020s and beyond, "Ocean Worlds" of the outer Solar System (e.g., Enceladus and Europa), as well as Mars, represent accessible targets that likely provide habitable environments that may support extant life. NASA Ames Research Center (ARC) is currently developing a multi-dimensional approach, led by astrobiology scientists in the ARC Space Sciences Division, technologists in the ARC Exploration Technology Directorate, and small payload engineers in the ARC Mission Design Division, to enable the definitive detection of extant extraterrestrial life in future NASA missions.

habitable environments↗
NASA NTRS2004

Waves on Seas of Mars and Titan: Wind-Tunnel Experiments on Wind-Wave Generation in Extraterrestrial Atmospheres

The generation of waves by winds across Earth's water oceans is a topic of enduring fascination. However, the physics of the problem are rather forbidding and thus the relationships between real-world windspeed and sea state tend to be empirical. Such empirical relations are of limited utility in environments where the physical parameters are different, such as the surfaces of other planets. These environments have only recently come to oceanographers attention, with the discovery of ancient shorelines and lakes on Mars, and the prospects for and recent evidence of lakes and seas of liquid hydrocarbons on Saturn's moon Titan. We are aware of only one other published experimental wind-water tunnel study where the fluid parameters have been varied. This used artificially-generated mm-scale waves at 3.8-7.6 Hz in water, glycerol solutions (higher viscosity) and surfactant solutions (lower surface tension). Lower viscosity solutions had higher wave growth rates: surprisingly, higher surface tension led to more rapid wave growth. The liquid density was not appreciably varied, and 1 bar air was used throughout.We used the MARSWIT (Mars Wind Tunnel) operated by ASU at NASA Ames. A fiberglass tray (5 cm x 120 cm x 75 cm) was installed in the tunnel, with an approx. 1:5 ramp to prevent strong flow separation. The tray was filled to a depth of about 4 cm. Sensors were clamped to the tray itself or held by a steel and aluminium frame just above the water level. A towel was draped on the water surface at the downwind end of the tray to act as a damper to suppress wave reflection. Position-sensitive infrared (IR) reflection sensors (Sharp GP12D02) and ultrasonic rangers (Devantech DF-04) used in mobile robotics were used as water level sensors. The tray was observed with a video camera, whose output could be viewed on a monitor and recorded on VHS tape.

Lorenz, R. D.↗
NASA NTRS2005

Characterization of a Subsurface Biosphere in a Massive Sulfide Deposits at Rio Tinto, Spain: Implications for Extant Life on Mars

The recent discovery of abundant sulfate minerals, particularly Jarosite by the Opportunity Rover at Sinus Merdiani on Mars has been interpreted as evidence for an acidic lake or sea on ancient Mars [1,2], since the mineral Jarosite is soluble in liquid water at pH above 4. The most likely mechanism to produce sufficient protons to acidify a large body of liquid water is near surface oxidation of pyrite rich deposits [3]. The acidic waters of the Rio Tinto, and the associated deposits of Hematite, Goethite, and Jarosite have been recognized as an important chemical analog to the Sinus Merdiani site on Mars [4]. The Rio Tinto is a river in southern Spain that flows 100 km from its source in the Iberian pyrite belt, one of the Earth s largest Volcanically Hosted Massive Sulfide (VHMS) provinces, into the Atlantic ocean. The river originates in artesian springs emanating from ground water that is acidified by the interaction with subsurface pyrite ore deposits. The Mars Analog Rio Tinto Experiment (MARTE) has been investigating the hypothesis that a subsurface biosphere exists at Rio Tinto living within the VHMS deposit living on chemical energy derived from sulfur and iron minerals. Reduced iron and sulfur might provide electron donors for microbial metabolism while in situ oxidized iron or oxidants entrained in recharge water might provide electron acceptors.

Stoker, C. R.↗
NASA NTRS2005

Characterization of a Subsurface Biosphere in a Massive Sulfide Deposit At Rio Tinto, Spain: Implications For Extant Life On Mars

The recent discovery of abundant sulfate minerals, particularly Jarosite by the Opportunity Rover at Sinus Merdiani on Mars has been interpreted as evidence for an acidic lake or sea on ancient Mars [1,2], since the mineral Jarosite is soluble in liquid water at pH above 4. The most likely mechanism to produce sufficient protons to acidify a large body of liquid water is near surface oxidation of pyrite rich deposits [3]. The acidic waters of the Rio Tinto, and the associated deposits of Hematite, Goethite, and Jarosite have been recognized as an important chemical analog to the Sinus Merdiani site on Mars [4]. The Rio Tinto is a river in southern Spain that flows 100 km from its source in the Iberian pyrite belt, one of the Earth's largest Volcanically Hosted Massive Sulfide (VHMS) provinces, into the Atlantic ocean. The river originates in artesian springs emanating from ground water that is acidified by the interaction with subsurface pyrite ore deposits. The Mars Analog Rio Tinto Experiment (MARTE) has been investigating the hypothesis that a subsurface biosphere exists at Rio Tinto living within the VHMS deposit living on chemical energy derived from sulfur and iron minerals. Reduced iron and sulfur might provide electron donors for microbial metabolism while in situ oxidized iron or oxidants entrained in recharge water might provide electron acceptors.

Stoker, C. R.↗
NASA NTRS1981

Tectonics and evolution of Venus

Earlier data synthesized with data recently obtained by the Pioneer Venus Orbiter are analyzed with regard to general tectonics, interior, and long-term evolution of Venus. Comprehensive topographic maps, global properties of Venus, and variations in its gravity field are investigated, and bulk properties of Venus, earth, Mars, the sun, and chondritic meteorites relevant to planetary internal structure and evolution are studied. Although Venus was found to differ less than 30% from earth in comparing all important bulk properties, it appears to have evolved differently. It is noted that a slow rotation rate, the absence of a satellite, the virtual absence of a magnetic field, the dearth of water in the atmosphere, the abundance of primordial argon, and the high surface temperature, are properties in which Venus differs most from the earth. Further results showing the positive correlation of gravity and topography at all wavelengths and the apparent absence of any feature like an ocean indicate that Venus is a one-plate planet and its evolution apparently resembles that of Mars more than that of the earth.

Phillips, R. J.↗
NASA NTRS1992

Forsterite/melt partitioning of argon and iodine: Implications for atmosphere formation by outgassing of an early Martian magma ocean

Argon and Xe in the Martian atmosphere are radiogenic relative to the Martian mantle if the SNC meteorites are from Mars. Decay of the short lived isotope I-129 to Xe-129 (t sub 1/2 = 16 m.y.) is the most plausible source of the radiogenic Xe. This short half life constrains any process responsible for the elevated Xe-129/Xe-132 ratio of the Martian atmosphere to occur very early in solar system history. Musselwhite et al. proposed that the differential solubility of I and Xe in liquid water played a key role in producing the radiogenic signature in the Martian atmosphere. Here we explore an alternative hypothesis involving purely igneous processes, and motivated in part by new experimental results on the partitioning of I and Xe between minerals and melt.

Musselwhite, Donald S.↗
NASA NTRS2004

Workshop on Oxygen in the Terrestrial Planets

This volume contains abstracts that have been accepted for presentation at the Workshop on Oxygen in the Terrestrial Planets, July 20-23,2004, Santa Fe, New Mexico. The contents include: 1) Experimental Constraints on Oxygen and Other Light Element Partitioning During Planetary Core Formation; 2) In Situ Determination of Fe(3+)/SigmaFe of Spinels by Electron Microprobe: An Evaluation of the Flank Method; 3) The Effect of Oxygen Fugacity on Large-Strain Deformation and Recrystallization of Olivine; 4) Plagioclase-Liquid Trace Element Oxygen Barometry and Oxygen Behaviour in Closed and Open System Magmatic Processes; 5) Core Formation in the Earth: Constraints from Ni and Co; 6) Oxygen Isotopic Compositions of the Terrestrial Planets; 7) The Effect of Oxygen Fugacity on Electrical Conduction of Olivine and Implications for Earth s Mantle; 8) Redox Chemical Diffusion in Silicate Melts: The Impact of the Semiconductor Condition; 9) Ultra-High Temperature Effects in Earth s Magma Ocean: Pt and W Partitioning; 10) Terrestrial Oxygen and Hydrogen Isotope Variations: Primordial Values, Systematics, Subsolidus Effects, Planetary Comparisons, and the Role of Water; 11) Redox State of the Moon s Interior; 12) How did the Terrestrial Planets Acquire Their Water?; 13) Molecular Oxygen Mixing Ratio and Its Seasonal Variability in the Martian Atmosphere; 14) Exchange Between the Atmosphere and the Regolith of Mars: Discussion of Oxygen and Sulfur Isotope Evidence; 15) Oxygen and Hydrogen Isotope Systematics of Atmospheric Water Vapor and Meteoric Waters: Evidence from North Texas; 16) Implications of Isotopic and Redox Heterogeneities in Silicate Reservoirs on Mars; 17) Oxygen Isotopic Variation of the Terrestrial Planets; 18) Redox Exchanges in Hydrous Magma; 19) Hydrothermal Systems on Terrestrial Planets: Lessons from Earth; 20) Oxygen in Martian Meteorites: A Review of Results from Mineral Equilibria Oxybarometers; 21) Non-Linear Fractionation of Oxygen Isotopes Implanted in Lunar Metal Grains: Solar, Lunar or Terrestrial Origin? 22) Isotopic Zoning in the Inner Solar System; 23) Redox Conditions on Small Bodies; 24) Determining the Oxygen Fugacity of Lunar Pyroclastic Glasses Using Vanadium Valence - An Update; 25) Mantle Redox Evolution and the Rise of Atmospheric O2; 26) Variation of Kd for Fe-Mg Exchange Between Olivine and Melt for Compositions Ranging from Alkaline Basalt to Rhyolite; 27) Determining the Partial Pressure of Oxygen (PO,) in Solutions on Mars; 28) The Influence of Oxygen Environment on Kinetic Properties of Silicate Rocks and Minerals; 29) Redox Evolution of Magmatic Systems; 30) The Constancy of Upper Mantlefo, Through Time Inferred from V/Sc Ratios in Basalts: Implications for the Rise in Atmospheric 0 2; 31) Nitrogen Solubility in Basaltic Melt. Effects of Oxygen Fugacity, Melt Composition and Gas Speciation; 32) Oxygen Isotope Anomalies in the Atmospheres of Earth and Mars; 33) The Effect of Oxygen Fugacity on Interdiffusion of Iron and Magnesium in Magnesiowiistite 34) The Calibration of the Pyroxene Eu-Oxybarometer for the Martian Meteorites; 35) The Europium Oxybarometer: Power and Pitfalls; 36) Oxygen Fugacity of the Martian Mantle from PigeoniteMelt Partitioning of Samarium, Europium and Gadolinium; 37) Oxidation-Reduction Processes on the Moon: Experimental Verification of Graphite Oxidation in the Apollo 17 Orange Glasses; 38) Oxygen and Core Formation in the Earth; 39) Geologic Record of the Atmospheric Sulfur Chemistry Before the Oxygenation of the Early Earth s Atmosphere; 40) Comparative Planetary Mineralogy: V/(CrCAl) Systematics in Chromite as an Indicator of Relative Oxygen Fugacity; 41) How Well do Sulfur Isotopes Constrain Oxygen Abundance in the Ancient Atmospheres? 42) Experimental Constraints on the Oxygen Isotope (O-18/ O-16) Fractionation in the Ice vapor and Adsorbant vapor Systems of CO2 at Conditions Relevant to the Surface of Mars; 43) Micro-XANES Measurements on Experimental Spinels andhe Oxidation State of Vanadium in Spinel-Melt Pairs; 44) Testing the Magma Ocean Hypothesis Using Metal-Silicate Partitioning of Te, Se and S; 45) Solubility of Oxygen in Liquid Iron at High Pressure and Consequences for the Early Differentiation of Earth and Mars Metallic Liquid Segregation in Planetesimals; 46) Oxygen Fugacity of Lunar Basalts and the Lunar Mantle. Range of fo2 and the Effectiveness of Oxybarometers; 47) Thermodynamic Study of Dissociation Processes of Molecular Oxygen in Vapor over Oxide Compounds; 48) Oxygen Profile of a Thermo-Haliophilic Community in the Badwater Salt Flat; 49) Oxygen Barometry Using Synchrotron MicroXANES of Vanadium; 50) Mass-Independent Isotopic Fractionation of Sulfur from Sulfides in the Huronian Supergroup, Canada; 51) Mass Independent Isotopes and Applications to Planetary Atmospheres; 52) Electrical Conductivity, Oxygen Fugacity, and Mantle Materials; 53) Crustal Evolution and Maturation on Earth: Oxygen Isotope Evidence; 54) The Oxygen Isotope Composition of the Moon: Implications for Planet Formation; 55) Oxygen Isotope Composition of Eucrites and Implications for the Formation of Crust on the HED Parent Body; and 56) The Role of Water in Determining the Oxygen Isotopic Composition of Planets.

Source record↗
NASA NTRS2007

Digital Learning Network Education Events of NASA's Extreme Environments Mission Operations

NASA's Digital Learning Network (DLN) reaches out to thousands of students each year through video conferencing and web casting. The DLN has created a series of live education videoconferences connecting NASA s Extreme Environment Missions Operations (NEEMO) team to students across the United States. The programs are also extended to students around the world live web casting. The primary focus of the events is the vision for space exploration. During the programs, NEEMO Crewmembers including NASA astronauts, engineers and scientists inform and inspire students about the importance of exploration and share the impact of the project as it correlates with plans to return to the moon and explore the planet Mars. These events highlight interactivity. Students talk live with the aquanauts in Aquarius, the National Oceanic and Atmospheric Administration s underwater laboratory. With this program, NASA continues the Agency s tradition of investing in the nation's education programs. It is directly tied to the Agency's major education goal of attracting and retaining students in science, technology, and engineering disciplines. Before connecting with the aquanauts, the students conduct experiments of their own designed to coincide with mission objectives. This paper describes the events that took place in September 2006.

Paul, Heather↗
NASA NTRS2017

Orion Multi-Purpose Crew Vehicle Solving and Mitigating the Two Main Cluster Pendulum Problem

The Orion Multi-purpose Crew Vehicle (MPCV) Orion spacecraft will return humans from beyond earth's orbit, including Mars and will be required to land 20,000 pounds of mass safely in the ocean. The parachute system nominally lands under 3 main parachutes, but the system is designed to be fault tolerant and land under 2 main parachutes. During several of the parachute development tests, it was observed that a pendulum, or swinging, motion could develop while the Crew Module (CM) was descending under two parachutes. This pendulum effect had not been previously predicted by modeling. Landing impact analysis showed that the landing loads would double in some places across the spacecraft. The CM structural design limits would be exceeded upon landing if this pendulum motion were to occur. The Orion descent and landing team was faced with potentially millions of dollars in structural modifications and a severe mass increase. A multidisciplinary team was formed to determine root cause, model the pendulum motion, study alternate canopy planforms and assess alternate operational vehicle controls & operations providing mitigation options resulting in a reliability level deemed safe for human spaceflight. The problem and solution is a balance of risk to a known solution versus a chance to improve the landing performance for the next human-rated spacecraft.

Ali, Yasmin↗
NASA NTRS1999

Lipid synthesis under hydrothermal conditions by Fischer-Tropsch-type reactions

Ever since their discovery in the late 1970's, mid-ocean-ridge hydrothermal systems have received a great deal of attention as a possible site for the origin of life on Earth (and environments analogous to mid-ocean-ridge hydrothermal systems are postulated to have been sites where life could have originated or Mars and elsewhere as well). Because no modern-day terrestrial hydrothermal systems are free from the influence of organic compounds derived from biologic processes, laboratory experiments provide the best opportunity for confirmation of the potential for organic synthesis in hydrothermal systems. Here we report on the formation of lipid compounds during Fischer-Tropsch-type synthesis from aqueous solutions of formic acid or oxalic acid. Optimum synthesis occurs in stainless steel vessels by heating at 175 degrees C for 2-3 days and produces lipid compounds ranging from C2 to > C35 which consist of n-alkanols, n-alkanoic acids, n-alkenes, n-alkanes and alkanones. The precursor carbon sources used are either formic acid or oxalic acid, which disproportionate to H2, CO2 and probably CO. Both carbon sources yield the same lipid classes with essentially the same ranges of compounds. The synthesis reactions were confirmed by using 13C labeled precursor acids.

Non-NASA Center↗