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All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Microbial Habitability in Gale Crater: Sample Analysis at Mars (SAM) Instrument Detection of Microbial Essential Carbon and Nitrogen

Chemical analyses of Mars soils and sediments from previous landed missions have demonstrated that Mars surface materials possessed major (e.g., P, K, Ca, Mg, S) and minor (e.g., Fe, Mn, Zn, Ni, Cl) elements essential to support microbial life. However, the detection of microbial essential organic-carbon (C) and nitrate have been more elusive until the Mars Science Laboratory (MSL) rover mission. Nitrate and organic-C in Gale Crater, Mars have been detected by the Sample Analysis at Mars (SAM) instrument onboard the MSL Curiosity rover. Eolian fines and drilled sedimentary rock samples were heated in the SAM oven from approximately 30 to 860 degrees Centigrade where evolved gases (e.g., nitrous oxide (NO) and CO2) were released and analyzed by SAM’s quadrupole mass spectrometer (MS). The temperatures of evolved NO was assigned to nitrate while evolved CO2 was assigned to organic-C and carbonate. The CO2 releases in several samples occurred below 450 degrees Centigrade suggesting organic-C dominated in those samples. As much as 7 micromoles NO3-N per gram and 200 micromoles CO2-C per gram have been detected in the Gale Crater materials. These N and C levels coupled with assumed microbial biomass (9 x 10 (sup -7) micrograms per cell) C (0.5 micrograms C per micrograms cell) and N (0.14 micrograms N per micrograms cell) requirements, suggests that less than 1 percent and less than 10 percent of Gale Crater C and N, respectively, would be required if available, to accommodate biomass requirements of 1 by 10 (sup 5) cells per gram sediment. While nitrogen is the limiting nutrient, the potential exists that sufficient N and organic-C were present to support limited heterotrophic microbial populations that may have existed on ancient Mars.

Sutter, B.↗
NASA NTRS2016

The Sample at Mars Analysis (SAM) Detections of CO2 and CO in Sedimentary Material from Gale Crater, Mars: Implications for the Presence of Organic Carbon and Microbial Habitability on Mars

Sedimentary rock samples heated to 860 degrees Centigrade in the SAM (Sample at Mars) instrument evolved CO2 and CO indicating the presence of organic-carbon(C) in Gale Crater materials. Martian or exogenous (meteoritic, interplanetary dust) CO2 and CO could be derived from combustion of simple organics (less than 300 degrees Centigrade), complex refractory organics/amorphous carbon (300-600 degrees Centigrade), and/or magmatic carbon (greater than 600 degrees Centigrade) as result of thermal decomposition of Gale Crater perchlorates, and sulfates present that produce O2. Oxidized organic compounds could also evolve CO2 and CO over broad temperature range (150 to 800 degrees Centigrade) and such organics are expected on Mars via exogenous sources. Alternatively, organic-C could also have been oxidized to carboxylic acids [e.g, mellitic acid (RCOOH), acetate (CH3CO2-), and oxalates (C2O42-)] by oxidative radiolytic weathering, or other oxidation processes. The presence of oxidized organics is consistent with the limited detection of reduced organic-C phases by the SAM-gas chromatography. Organic-C content as determined by CO2 and CO contents could range between 800 and 2400 parts per million C indicating that substantial organic-C component is present in Gale Crater. There are contributions from SAM background however, even in worst-case scenarios, this would only account for as much as half of the detected CO2 and CO. Nevertheless, if organic-C levels were assumed to have existed in a reduced form on ancient Mars and this was bioavailable C, then less than 1 percent of C in Gale Crater sediments could have supported an exclusively heterotrophic microbial population of 1 by 10 (sup 5) cells per gram sediment (assumes 9 by 10 (sup -7) microgram per cell and 0.5 micrograms C per microgram cell). While other essential nutrients (e.g., S and P) could be limiting, organic-C contents, may have been sufficient to support limited heterotrophic microbial populations on ancient Mars.

Sutter, Brad↗
NASA NTRS2016

Potential Precursor Compounds for Chlorohydrocarbons Detected in Gale Crater, Mars, by the SAM Instrument Suite on the Curiosity Rover

The detection of chlorinated organic compounds in near-surface sedimentary rocks by the Sample Analysis at Mars (SAM) instrument suite aboard the Mars Science Laboratory Curiosity rover represents an important step toward characterizing habitable environments on Mars. However, this discovery also raises questions about the identity and source of their precursor compounds and the processes by which they become chlorinated. Here we present the results of analog experiments, conducted under conditions similar to SAM gas chromatography-mass spectrometry analyses, in which we pyrolyzed potential precursor compounds in the presence of various Cl salts and Fe oxides that have been identified in Martian sediments. While chloromethanes could not be unambiguously identified, 1,2-dichloropropane (1,2-DCP), which is one of the chlorinated compounds identified in SAM data, is formed from the chlorination of aliphatic precursors. Additionally, propanol produced more 1,2-DCP than nonfunctionalized aliphatics such as propane or hexanes. Chlorinated benzenes ranging from chlorobenzene to hexachlorobenzene were identified in experiments with benzene carboxylic acids but not with benzene or toluene. Lastly, the distribution of chlorinated benzenes depended on both the substrate species and the nature and concentration of the Cl salt. Ca and Mg perchlorate, both of which release O2 in addition to Cl2 and HCl upon pyrolysis, formed less chlorobenzene relative to the sum of all chlorinated benzenes than in experiments with ferric chloride. FeCl3, a Lewis acid, catalyzes chlorination but does not aid combustion. Accordingly, both the precursor chemistry and sample mineralogy exert important controls on the distribution of chlorinated organics.

Miller, Kristen E.↗
DOE OSTI2024

Verification and Demonstration of One-Dimensional Freezing Model in SAM for Salt-Cooled Reactor Analysis Applications

This work presented the development and implementation of the one-dimensional freezing model in system analysis code, SAM, as well as code verification, and code demonstration during a postulated overcooling transient, for fluoride salt-cooled high-temperature reactor (FHR) system and safety analysis applications. The paper at first summarized the freezing model, finite element numerical method, and special numerical treatment for handling phase appearance/disappearance. Analytical solutions were derived for two cases (with and without solid walls) for code verifications purpose. As expected, numerical results predicted by the SAM code agreed very well with the analytical solution. A code demonstration was then performed on a postulated protected overcooling event transient of a generic reference PB-FHR design. The code was found to successfully predict salt freezing during such a postulated event. However, due to lack of salt freezing testing data, code validation has not been performed in this work, which will be pursued in later studies when such data becomes available.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2025

System Advisor Model (SAM) Improvements for Emerging Solar Thermal Applications

The System Advisor Model (SAM) is an open-source tool developed by NREL to simulate the techno-economic performance of technologies like photovoltaics, solar thermal, wind, and geothermal. NREL has recently completed, active, and planned projects to improve the solar thermal models in SAM and its underlying code base to represent emerging component technologies, systems, and applications. This poster describes new capabilities in the SolarPILOT optical modeling tool, supercritical carbon dioxide (sCO2) power cycles, and solar industrial process heat.

14 SOLAR ENERGY↗
DOE OSTI2024

SAM Code Improvements for Molten Salt Reactor Transient and Species Transport Modeling

The SAM code is under development and supported by DOE-NE’s Nuclear Energy Advanced Modeling and Simulation program as a modern system-level modeling and simulation tool for advanced non-light water reactor safety analyses. These advanced reactor concepts incorporate novel and improved approaches to achieve safety and economic feasibility. This report summarizes FY24 efforts in addressing the modeling gaps in SAM for molten salt reactor (MSR) applications. These efforts focused on the solver performance related to species transport, usability of the flowing decay heat and delayed neutron precursor capabilities, and modeling gaps related to fission product transport throughout the system.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

FY24 Mole Development Updates and SAM-Mole Coupling for MSR Species Transport Applications

In this report, a new coupling strategy linking Mole to SAM is demonstrated where SAM is used to drive the solution and Mole is used primarily as a library for mass transport coefficient models. Groundwork is laid to transition Mole into a harbor for various mass transfer coefficient models, which generally take the form of scalar, auxiliary Multiphysics Object-Oriented Simulation Environment (MOOSE) kernels. It is envisioned that these models will be agnostic to the spatial discretization scheme and can be used across the MOOSE ecosystem, providing a centralized library for certain mass transfer coefficients to MOOSE codes that must account for liquid-to-vapor and vapor-to-liquid mass transport phenomena for both high-volatility and low-volatility species.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2025

Advanced System Thermal Fluids Solver Development for SAM

This work summarizes a feasibility study on testing numerical algorithms that are suitable and efficient for advanced system analysis code development under the mutli-physics framework, MOOSE. The key is the implementation of a high-order one-dimensional staggered-grid finite volume method (SG-FVM), and its direct interaction with the linear/nonlinear solver, PETSc. Leveraging the existing capabilities of the SAM code, significant code coverages were established in the finite volume method code. This in turn allows for a suite of test problems with different problem sizes and levels of complexity to be used to quantify the performance improvement of the finite volume method code. As evidently shown in this study, the implemented SG-FVM demonstrated superior performance improvement against a direct finite element method implementation through MOOSE for the wide range of selected problems. On two computer systems, the speedup was observed to be significant, with at least one order of magnitude of solving time reduction. In addition, for a complex reactor model, transient simulation was performed using the finite volume method code, the results of which agree very well with the reference results from the finite element method code. Overall, this study demonstrates a successful feasibility study on the proposed numerical algorithms and software structure to support advanced system analysis tool development. In this work, short-term priority development and testing items were identified, and long-term code adoption and integration plans were made for the eventual deployment of the finite volume method in the SAM code.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1976

SAM 2 balloon test (stratospheric aerosol measurement)

As a parallel effort to the LACATE balloon experiment a small optical system was constructed to enable a balloon test of a diode filter system similar to the type planned for the Nimbus-G SAM II experiment. The system was called the SAM II Balloon Test. Results of the balloon flight are summarized.

Pepin, T. J.↗
NASA NTRS1980

The mechanisms of the SAMS experiment flown on Nimbus 7 with particular reference to the 2 axis scanning mirror

The stratospheric and mesospheric sounder (SAMS) experiment on Nimbus 7 includes a 2 axis scanning mirror and 7 pressure modulator cells. The SAMS experiment is a limb sounding instrument to measure the temperature profile and minor constituents of the atmosphere. The limb scan requires small mirror steps over a 3 deg range, while the scan in azimuth is in larger steps over a 15 deg range. The mirror is plane, 20 cm in diameter, and of zero expansion glass-ceramic. It is supported on two tilt tables, fitted one on the other, with the axes at right angles. The angle of tilt is adjusted by means of recirculating ball screws which are ion plated with lead for lubrication and driven by stepper motors. The seven gas filled cells are each pressure modulated by a 3 cm diameter, 0.3 cm stroke piston which is supported by diaphragm springs and driven electromagnetically at the system's mechanical resonant frequency. The mean pressure of the filling gas, which is the atmospheric constituent being measured, is changed by varying the temperature of a suitable molecular sieve.

Hadley, H.↗
NASA NTRS1979

XPS and SAM studies of the surface chemistry of lunar impact glasses including 12054

We report and discuss quantitative X-ray photoemission (XPS) analyses of mm size areas and qualitative scanning Auger microprobe (SAM) analyses of micron size areas on the surfaces of impact glass coatings found on fragments in the 14161 coarse fines and on the top surface, and a reentrant crack surface of rock 12054. The data suggest that some segregation occurs during impact glass formation leading to surface enrichments in Si and depletions in Mg, Al, Ca, and Ti. The magnitude of the effect appears fairly small, although the complexity of the surfaces severely complicates the data analysis. Because of the complexity of the surfaces, both XPS and SAM data were essential. A search for direct evidence of either solar wind sputter erosion or vapor deposition on the exposed top surface of 12054 provided interesting results which we cannot yet fully interpret. Both this surface and the surface from the re-entrant crack showed enrichments of more than a factor of two in Fe with respect to the bulk.

Housley, R. M.↗
NASA NTRS1981

Satellite and correlative measurements of the stratospheric aerosol. II Comparison of measurements made by SAM II, dustsondes and airborne lidar

Results are shown from the first set of measurements conducted to validate extinction data from the Stratospheric Aerosol Measurement II (SAM II). Dustsonde-measured number density profiles and lidar-measured backscattering profiles for two days are converted to extinction profiles, and are shown to agree within their respective uncertainties at all heights above the tropopause. Near the tropopause, agreement depends on use of model size distributions with larger particles, having radii greater than 0.6 microns. The presence of such large particles is supported by measurements made elsewhere, is suggested by the in situ size distribution measurements reported, and is likely to have an important bearing on the radiative impact of the total stratospheric aerosol. It is concluded that the SAM II extinction data and uncertainty estimates are supported.

Russell, P. B.↗
NASA NTRS1982

Polar stratospheric cloud sightings by SAM II

The functions and data gained regarding stratospheric cloud sightings by the stratospheric aerosol measurement (SAM) II experiment on board the Numbus 7 spacecraft are reported. SAM II comprises a single channel sun photometer centered at 1.0 micron wavelength for measuring the solar intensity when the sun descends below an apparent 300 km altitude until the sun is occulted by clouds or the horizon. Readings are also made during sunrise in an opposite fashion. Transmission profiles are developed from the data and used to construct profiles of aerosol extinction with a 1 km resolution. Polar stratospheric clouds have been observed in more than 90% of the cases when the minimum temperature is 185 K or less, and 45% of the time when the temperature is 193 K or less. The clouds were more prevalent in the Antarctic winter than during the Arctic winter, and cloud height was lower than indicated by previous data.

Mccormick, M. P.↗
NASA NTRS1982

Validation of aerosol measurements by the satellite sensors SAM II and Sage

A global data base on stratospheric aerosols has been obtained with the aid of the sensors SAM II and SAGE since the satellites carrying the sensors were launched in October 1978 and Feburary 1979, respectively. Several major comparative experiments have been conducted to acquire correlative data for validating the extinction profiles measured by these satellite sensors. The present investigation has the objective to present results from the first two of these experiments, which were conducted at Sondrestorm, Greenland, in November 1978, and at Poker Flat, Alaska, in July 1979. In both experiments, extinction profiles derived from the correlative sensors (dustsonde, lidar, filter, wire impactor) agreed, to within their respective uncertainties, with the extinction profiles measured by SAM II and SAGE (which in turn agreed with each other).

Russell, P. B.↗
NASA NTRS1984

Satellite and correlative measurements of the stratospheric aerosol. III - Comparison of measurements by SAM II, SAGE, dustsondes, filters, impactors and lidar

The SAM II and SAGE satellite sensors, dustsondes, impactors, a filter collector and an airborne lidar were used in a large satellite validation experiment on July 16-19, 1979, at Poker Flat, Alaska. Independent measurements of extinction profiles by SAM II and SAGE are noted to agree with each other and with those derived from the other instruments (within combined uncertainties). The wire impactor-derived results, while also consistent with the others, are coarse due to the relatively large uncertainties in impactor-derived mass, extinction, and number of particles/unit volume whose radius is greater than x microns.

Russell, P. B.↗
NASA NTRS1985

SAM 2 measurements of the polar stratospheric aerosol, volume 5

The Stratospheric Aerosol Measurement (SAM) 2 sensor is aboard the Earth-orbiting Nimbus 7 spacecraft providing extinction measurements of the Antarctic and Arctic stratospheric aerosol with a vertical resolution of 1 km. Representative examples and weekly averages of aerosol data and corresponding temperature profiles for the time and place of each SAM 2 mesurement (Oct. 1980 through Apr. 1981) are presented. Contours of aerosol extinction as a function of altitude and longitude or time are plotted and weekly aerosol optical depths are calculated. Seasonal variations and variations in space (altitude and longitude) for both polar regions are easily seen. Stratospheric optical depths are 0.002 to 0.003 for the Antarctic region and 0.005 to 0.006 at the beginning to 0.002 to 0.003 at the end of the time period for the Arctic region. The Northern Hemisphere values are quite large due mainly to the eruption of Mount St. Helens (46.2 deg N, 122.2 deg W) in May 1980. Polar stratospheric clouds at altitudes of about 20 km were observed during the Arctic winter. A ready-to-use format containing a representative sample of the fifth 6 months of data to be used in atmospheric and climatic studies is presented.

Mccormick, M. P.↗
NASA NTRS1986

SAM 2 measurements of the polar stratospheric aerosol, volume 2

The Stratospheric Aerosol Measurement (SAM) 2 sensor aboard Nimbus 7 is providing extinction measurements of Antarctic and Arctic stratospheric aerosols with a vertical resolution of 1 km. Representative examples and weekly averages including corresponding temperature profiles provided by NOAA for the time and place of each SAM 2 measurement (Oct. 1981 - Apr. 1982) are presented. Contours of aerosol extinction as a function of altitude and longitude or time are plotted, and aerosol optical depths are calculated for each week. Typical values of aerosol extinction at 1.0 micron in the main lower stratospheric aerosol layer for this time period are 2 to 4 times 10 to the -4 power/km. for the Antarctic region and 0.5 to 1 times 10 to the -3 power/km. for the Arctic region. Stratospheric optical depths are about 0.001 to 0.004 for the Antarctic region and 0.003 to 0.004 at the beginning to about 0.006 at the end of the time period for the Arctic region. Polar stratospheric clouds (PSC's) were observed during the Arctic winter, as expected. This report provides, in a ready-to-use format, a representative sample of the seventh semester of data to be used in atmospheric and climatic studies.

Mccormick, M. P.↗
NASA NTRS1986

SAM 2 measurements of the polar stratospheric aerosol, volume 8

The Stratospheric Aerosol Measurement (SAM) 2 sensor aboard Nimbus 7 is providing extinction measurements of Antarctic and Arctic stratospheric aerosols with a vertical resolution of 1 km. Representative examples and weekly averages including corresponding temperature profiles provided by NOAA for the time and place of each SAM 2 measurement (Apr. 1982 - Oct. 1982) are presented. Contours of aerosol extinction as a function of altitude and longitude or time are plotted, and aerosol optical depths are calculated for each week. Typical values of aerosol extinction at 1.0 microns in the main stratospheric aerosol layer are approximately 4 to 6 times .0001/km at the beginning to 1 to 2 times .001/km at the end of the time period for the Antarctic region and approximately 1 to 3 times .001/km for the Arctic region throughout the time period. Stratospheric optical depths are about 0.002 to 0.009 for the Antarctic region and about 0.007 at the beginning to 0.024 at the end of the time period for the Arctic region. Polar stratospheric clouds were observed during the Antarctic winter, as expected. This report provides, in a ready-to-use format, a representative sample of the eighth 6 months of data to be used in atmospheric and climatic studies.

Mccormick, M. P.↗