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McKay, C. P.

Publications and source records attributed to McKay, C. P..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Chemistry and Mineralogy of Antarctica Dry Valley Soils: Implications for Mars

The Antarctic Dry Valleys (ADV) comprise the largest ice-free region of Antarctica. Precipitation almost always occurs as snow, relative humidity is frequently low, and mean annual temperatures are about -20 C. The ADV soils have previously been categorized into three soil moisture regimes: subxerous, xerous and ultraxerous, based on elevation and climate influences. The subxerous regime is predominately a coastal zone soil, and has the highest average temperature and precipitation, while the ultraxerous regime occurs at high elevation (>1000 m) and have very low temperature and precipitation. The amounts and types of salts present in the soils vary between regions. The nature, origin and significance of salts in the ADV have been previously investigated. Substantial work has focused on soil formation in the ADVs, however, little work has focused on the mineralogy of secondary alteration phases. The dominant weathering process in the ADV region is physical weathering, however, chemical weathering has been well documented. The objective of this study was to characterize the chemistry and mineralogy, including the alteration mineralogy, of soils from two sites, a subxerous soil in Taylor Valley, and an ultraxerous soil in University Valley. The style of aqueous alteration in the ADVs may have implications for pedogenic processes on Mars.

Quinn, J. E.↗
NASA NTRS2011

LIFE: Enceladus Sample Return Mission Concept for Searching Evidence of Life

One of the most promising targets for the search for life other than Mars in our Solar System is the tiny Saturn moon Enceladus. The Cassini mission to the Saturian system detected an active region on Enceladus where small water particles and gas containing organic materials were being flung into space from a region near the south pole known as the tiger stripes. This discovery indicated that there is very likely a liquid subsurface ocean heated through tidal interactions as Enceladus orbits Saturn. On Earth, whenever there is an energy source, liquid water and organics, there is life; this makes Enceladus one of the prime candidates for a search for life missions. In this presentation, we describe LIFE (Life Investigation For Enceladus) sample return concept from Enceladus in the search for evidence of life.

Enceladus↗
NASA NTRS2010

Mineralogy of Antarctica Dry Valley Soils: Implications for Pedogenic Processes on Mars

The Antarctic Dry Valleys (ADVs) located in the Transantarctic Mountains are the coldest and driest locations on Earth. The mean annual air temperature is -20 C or less and the ADVs receive 100mm or less of precipitation annually in the form of snow. The cold and dry climate in the ADVs is one of the best terrestrial analogs for the climatic conditions on Mars [2]. The soils in the ADVs have been categorized into three soil moisture zones: subxerous, xerous and ultraxerous. The subxerous zone is a coastal region in which soils have ice-cemented permafrost relatively close to the surface. Moisture is available in relatively large amounts and soil temperatures are above freezing throughout the soil profile (above ice permafrost) in summer months. The xerous zone, the most widespread of the three zones, is an inland region with a climate midway between the subxerous and ultraxerous. The soils from this zone have dry permafrost at moderate depths (30-75cm) but have sufficient water in the upper soil horizons to allow leaching of soluble materials. The ultraxerous zone is a high elevation zone, where both temperature and precipitation amounts are very low resulting in dry permafrost throughout the soil profile. The three moisture regime regions are similar to the three microclimatic zones (coastal thaw, inland mixed, stable upland) defined by Marchant and Head.

Quinn, J. E.↗
NASA NTRS2010

McMurdo Dry Valleys, Antarctica - A Mars Phoenix Mission Analog

The Phoenix mission (PHX; May 25 - Nov. 2, 2008) studied the north polar region of Mars (68deg N) to understand the history of water and potential for habitability. Phoenix carried with it a wet chemistry lab (WCL) capable of determining the basic solution chemistry of the soil and the pH value, a thermal and evolved-gas analyzer capable of determining the mineralogy of the soil and detecting ice, microscopes capable of seeing soil particle shapes, sizes and colors at very high resolution, and a soil probe (TECP) capable of detecting unfrozen water in the soil. PHX coincided with an international effort to study the Earth s polar regions named the International Polar Year (IPY; 2007-2008). The best known Earth analog to the Martian high-northern plains, where Phoenix landed, are the McMurdo Dry Valleys (MDV), Antarctica (Fig. 1). Thus, the IPY afforded a unique opportunity to study the MDV with the same foci - history of water and habitability - as PHX. In austral summer 2007, our team took engineering models of WCL and TECP into the MDV and performed analgous measurements. We also collected sterile samples and analyzed them in our home laboratories using state-of-the-art tools. While PHX was not designed to perform biologic analyses, we were able to do so with the MDV analog samples collected.

Tamppari, L. K.↗
NASA NTRS2009

Enceladus: An Active Cryovolcanic Satellite

Enceladus is one of the most remarkable satellites in the solar system, as revealed by Cassini's detection of active plumes erupting from warm fractures near its south pole. This discovery makes Enceladus the only icy satellite known to exhibit ongoing internally driven geological activity. The activity is presumably powered by tidal heating maintained by Enceladus 2:1 mean-motion resonance with Dione, but many questions remain. For instance, it appears difficult or impossible to maintain the currently observed radiated power (probably at least 6 GW) in steady state. It is also not clear how Enceladus first entered its current self-maintaining warm and dissipative state initial heating from non-tidal sources is probably required. There are also many unanswered questions about Enceladus interior. The silicate fraction inferred from its density of 1.68 g per cubic centimeter is probably differentiated into a core, though we have only indirect evidence for differentiation. Above the core there is probably a global or regional water layer, inferred from several models of tidal heating, and an ice shell thick enough to support the ~1 kilometer amplitude topography seen on Enceladus. It is possible that dissipation is largely localized beneath the south polar region. Enceladus surface geology, ranging from moderately cratered terrain to the virtually crater-free active south polar region, is highly diverse, tectonically complex, and remarkably symmetrical about the rotation axis and the direction to Saturn. South polar activity is concentrated along the four tiger stripe fractures, which radiate heat at temperatures up to at least 167 K and are the source of multiple plumes ejecting ~200 kilograms per second of H2O vapor along with significant N2 (or C2H4), CO2, CH4, NH3, and higher-mass hydrocarbons. The escaping gas maintains Saturn's neutral gas torus, and the plumes also eject a large number of micron-sized H2O ice grains that populate Saturn's E-ring. The mechanism that powers the plumes is not well understood, and whether liquid water is involved is a subject of active debate (but likely nonetheless). Enceladus provides a promising potential habitat for life in the outer solar system, and the active plumes allow the unique opportunity for direct sampling of that zone. Enceladus is thus a prime target for Cassini's continued exploration of the Saturn system, and will be a tempting target for future missions.

Spencer, J. R.↗
NASA NTRS2005

Formation of Martian Gullies by the Action of Liquid Water Flowing Under Current Martian Environmental Conditions

Images from the Mars Orbiter Camera (MOC) on the Mars Global Surveyor (MGS) spacecraft show geologically young small-scale features resembling terrestrial water-carved gullies. An improved understanding of these features has the potential to reveal important information about the hydrological system on Mars, which is of general interest to the planetary science community as well as the field of astrobiology and the search for life on Mars. The young geologic age of these gullies is often thought to be a paradox because liquid water is unstable at the Martian surface. Current temperatures and pressures are generally below the triple point of water (273 K, 6.1 mbar) so that liquid water will spontaneously boil and/or freeze. We therefore examine the flow of water on Mars to determine what conditions are consistent with the observed features of the gullies.

Heldmann, J. L.↗
NASA NTRS2005

Mars, Always Cold, Sometimes Wet: New Constraints on Mars Denudation Rates and Climate Evolution from Analog Studies at Haughton Crater, Devon Island, High Arctic

Analysis of crater modification on Mars and at Haughton Crater, Devon Island, High Arctic, which was recently shown to be significantly older than previously believed (Eocene age instead of Miocene) [1], suggest that Mars may have never been climatically wet and warm for geological lengths of time during and since the Late Noachian. Impact structures offer particularly valuable records of the evolution of a planet s climate and landscape through time. The state of exposure and preservation of impact structures and their intracrater fill provide clues to the nature, timing, and intensity of the processes that have modified the craters since their formation. Modifying processes include weathering, erosion, mantling, and infilling. In this study, we compare the modification of Haughton through time with that of impact craters in the same size class on Mars. We derive upper limits for time-integrated denudation rates on Mars during and since the Late Noachian. These rates are significantly lower than previously published and provide important constraints for Mars climate evolution.

Lee, Pascal↗
NASA NTRS2005

Dry Acid Deposition and Accumulation on the Surface of Mars and in the Atacama Desert, Chile

It has been discovered recently that soils from certain regions of the Chilean Atacama Desert have some characteristics that are similar to the surface materials tested by the Viking Landers. Navarro-Gonzalez et al. demonstrated that the quantity and diversity of heterotrophic bacteria increase as a function of local water availability in the Atacama, and that for some soil samples collected in the driest regions, no culturable bacteria could be isolated. Additionally, Navarro-Gonzalez et al. reported that pyrolysis-GCMS analysis of soils collected from these regions revealed extremely low levels of organic matter. Although the mechanism resulting in the low level of organics in these regions was not established by Navarro-Gonzalez, the condition of organic-depleted, near-sterile soil offers an interesting Earth analog of the martian surface material, as the Viking Gas Exchange (GEx) experiment and Labeled Release (LR) experiment were unable to demonstrate the presence of culturable bacteria, and the Viking pyrolysis- GCMS was unable to detect organic compounds.

Quinn, R. C.↗
NASA NTRS2005

A Compact Instrument for Remote Raman and Fluorescence Measurements to a Radial Distance of 100 m

Compact remote spectroscopic instruments that could provide detailed information about mineralogy, organic and biomaterials on a planetary surface over a relatively large area are desirable for NASA s planetary exploration program. Ability to explore a large area on the planetary surfaces as well as in impact craters from a fixed location of a rover or lander will enhance the probability of selecting target rocks of high scientific contents as well as desirable sites in search of organic compounds and biomarkers on Mars and other planetary bodies. We have developed a combined remote inelastic scattering (Raman) and laser-induced fluorescence emission (LIFE) compact instrument capable of providing accurate information about minerals, organic and biogenic materials to a radial distance of 100 m. Here we present the Raman and LIFE (R-LIFE) data set.

Sharma, S. K.↗
NASA NTRS2005

Experimental Study on Interactions Between H Atoms and Organic Haze

In Titan s atmosphere composed of N2 and CH4, irradiations of both solar ultraviolet light and charged particles induce active chemical reactions. In the processes of these reactions, a large amount of hydrogen (H) atoms are expected to be formed by dissociation of CH4 and other hydrocarbons [e.g., 1, 2]. Theoretical models suggest that these active H atoms need to be converted to stable hydrogen molecules (H2) efficiently to maintain unsaturated hydrocarbons and organic haze in Titan s atmosphere [e.g., 1]. Furthermore, molecular hydrogen is an important greenhouse effect gas in Titan s atmosphere, and small variation in its abundance strongly affects Titan s surface temperature [3]. Thus, the formation of H2 molecules from H atoms is a key reaction for both the atmospheric chemistry and the surface environment of Titan. Although several numerical calculations have been conducted to investigate the atmospheric chemistry of Titan with hypothesized recombination reactions of H atoms, such as catalytic scheme of C4H2 [e.g., 1, 2], it is still unclear what chemical reaction is responsible for the conversion of H atoms to H2 molecules in Titan s atmosphere.

Sekine, Y.↗
NASA NTRS2005

Infrared Spectroscopic Analyses of Sulfate, Nitrate, and Carbonate-bearing Atacama Desert Soils: Analogs for the Interpretation of Infrared Spectra from the Martian Surface

The Atacama Desert of northern Chile is the driest desert on Earth, receiving only a few mm of rain per decade. The Mars climate may, in the past, have been punctuated by short-lived episodes of aqueous activity. The paleo-Martian environment may have had aqueous conditions similar to the current conditions that exist in the Atacama, and Mars soils may have formed with soil chemistry and mineralogy similar to those found in the Atacama. Remote and in-situ analysis of the Martian surface using infrared technology has a long heritage. Future investigations of the subsurface mineralogy are likely to build upon this heritage, and will benefit from real life lessons to be learned from terrestrial analog studies. To that end, preliminary results from a near- and mid-infrared spectroscopic study of Atacama soil profiled at a range of depths are presented.

Dalton, J. B.↗
NASA NTRS2004

Analyses of IR-Stealthy and Coated Surface Materials: A Comparison of LIBS and Reflectance Spectra and Their Application to Mars Surface Exploration

Identification of non-silicate samples on Mars, such as carbonates, sulfates, nitrates, or evaporites in general, is important because of their association with aqueous processes and their potential as exobiology sites. Infrared (IR) and thermal emission (TE) spectroscopy have been considered the primary tools for remote identification of these minerals. This includes current and future orbital assets such as TES on MGS, THEMIS on Mars Odyssey, OMEGA on Mars Express, CRISM on MRO, and now the Mini-TES on the MER rovers. While reflectance and emission spectroscopy have clearly been the method of choice for these missions, the technique is not always successful in mineral identifications due to dust, surface weathering chemistry, coatings, or surface texture. Here we describe and show IR spectra of several such samples, and then report on the relative success of LIBS analyses in determining the rock type.

Wiens, R. C.↗
NASA NTRS2004

Oxygen Profile of a Thermo-Haliophilic Community in the Badwater Salt Flat

Badwater is the lowest, saltiest, and hottest, place in North America. This extreme environment is 86 meters (282 feet) below sea level surrounded by four mountain ranges. Due to the geographical location Badwater does not receive moisture from the prevailing winds, this intern results in a hot, arid, and salty environment. Despite these extreme living conditions, microbes manage to flourish within the salt flat. The salt acts as an insulator making life just beneath the surface more comfortable In this paper, we compare the microbial population versus oxygen concentration; and the importance of and the role of oxygen in metabolic functions by these thermo-haliophiles. Furthermore a model of the oxygen profile will also provide an insight to the oxygen cycle in salty environments. This research has implications for the limits of life on Earth and Mars. Recent results from the MER rovers show that water on Mars was very salty. Measuring the oxygen profile in these salty environments on Earth provides a framework within which potential life on Mars can be evaluated. The use of an oxygen profile could also be used as a search criteria for life.

Smith, H. D.↗
NASA NTRS2004

An Impact Triggered Runaway Greenhouse on Mars

When a planet is in radiative equilibrium, the incoming solar flux balances the outgoing longwave flux. If something were to perturb the system slightly, say the incoming solar flux increased, the planet would respond by radiating at a higher surface temperature. Since any radiation that comes in must go out, if the incoming is increased, the outgoing must also increase, and this increase manifests itself as a warmer equilibrium temperature. The increase in solar flux would correspond to an increase in temperature, which would increase the amount of water vapor in the atmosphere due to increased evaporation. Since water vapor is a greenhouse gas, it would absorb more radiation in the atmosphere leading to a yet warmer equilibrium temperature. The planet would reach radiative equilibrium at this new temperature. There exists a point, however, past which this positive feedback leads to a "runaway" situation. In this case, the planet does not simply evaporate a little more water and eventually come to a slightly higher equilibrium temperature. Instead, the planet keeps evaporating more and more water until all of the planet's available liquid and solid water is in the atmosphere. The reason for this is generally understood. If the planet's temperature increases, evaporation of water increases, and the absorption of radiation increases. This increases the temperature and the feedback continues until all water is in the atmosphere. The resulting equilibrium temperature is very high, much higher than the equilibrium temperature of a point with slightly lower solar flux. One can picture that as solar flux increases, planetary temperature also increases until the runaway point where temperature suddenly "jumps" to a higher value, in response to all the available water now residing in the atmosphere. This new equilibrium is called a "runaway greenhouse" and it has been theorized that this is what happened to the planet Venus, where the surface temperature is more than 700 K (427 C).

Segura, T. L.↗
NASA NTRS2004

Tumbleweed: Wind-propelled Surficial Measurements for Astrobiology and Planetary Science

Tumbleweed is a wind-propelled long-range vehicle based on well-developed and tested technology, instrumented to perform surveys Mars analog environments for habitability and suitable for a variety of missions on Mars. Tumbleweeds are light-weight and relatively inexpensive, making it very attractive for multiple deployments or piggy-backing on a larger mission. Tumbleweeds with rigid structures are also being developed for similar applications. Modeling and testing have shown that a 6 meter diameter Tumbleweed is capable of climbing 25 hills, traveling over 1 meter diameter boulders, and ranging over a thousand kilometers. Tumbleweeds have a potential payload capability of about 10 kilograms with approximately 10-20 Watts of power. Stopping for science investigations can also be accomplished using partial deflation or other braking mechanisms. Surveys for Astrobiology and other applications of tumbleweeds are shown.

Kuhlman, K. R.↗
NASA NTRS2004

Freshwater Microbialites of Pavilion Lake, British Columbia, Canada: A Limnological Investigation

Pavillion Lake is 5.7km long and an average of 0.8 km in width, and is located in Marble Canyon in the interior of British Columbia, Canada. It is a slightly alkaline, freshwater lake with a maximum-recorded depth of 65m. The basin walls of Pavilion Lake are lined with microbialite structures that are oriented perpendicularly to the shoreline, and which are found from depths of 5 meters to the bottom of the photic zone (light levels 1% of ambient; approximately 30m depth). These structures are speculated to have begun formation nearly 11,000 years ago, after the glacial retreat of the Cordilleran Ice Sheet. They are likely a distinctive assemblage of freshwater calcite microbialites, which display micromorphologies possibly related to the ancient Epiphyton and Girvanella classes of calcareous organosedimentary structures.

Lim, D. S. S.↗