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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Mechanical Description of the Mars Climate Sounder Instrument

This paper introduces the Mars Climate Sounder (MCS) Instrument of the Mars Reconnaissance Orbiter (MRO) spacecraft. The instrument scans the Martian atmosphere almost continuously to systematically acquire weather and climate observations over time. Its primary components are an optical bench that houses dual telescopes with a total of nine channels for visible and infrared sensing, and a two axis gimbal that provides pointing capabilities. Both rotating joints consist of an integrated actuator with a hybrid planetary/harmonic transmission and a twist cap section that enables the electrical wiring to pass through the rotating joint. Micro stepping is used to reduce spacecraft disturbance torques to acceptable levels while driving the stepper motors. To ensure survivability over its four year life span, suitable mechanical components, lubrication, and an active temperature control system were incorporated. Some life test results and lessons learned are provided to serve as design guidelines for actuator parts and flex cables.

rotating joints↗
NASA NTRS2012

Psychophysiological Assessment of Fatigue in Commercial Aviation Operations

The overall goal of this study is to improve our understanding of crew work hours, workload, sleep, fatigue, and performance, and the relationships between these variables on actual flight deck performance. Specifically, this study will provide objective measures of physiology and performance, which may benefit investigators in identifying fatigue levels of operators in commercial aviation and provide a way to better design strategies to limit crew fatigue. This research was supported by an agreement between NASA Ames Research Center and easyJet Airline Company, Ltd., Luton, UK. Twenty commercial pilots volunteered to participant in the study that included 15 flight duty days. Participants wore a Zephyr Bioharness ambulatory physiological monitor each flight day, which measured their heart rate, respiration rate, skin temperature, activity and posture. In addition, pilots completed sleep log diaries, self-report scales of mood, sleepiness and workload, and a Performance Vigilance Task (PVT). All data were sent to NASA researchers for processing and analyses. Heart rate variability data of several subjects were subjected to a spectral analysis to examine power in specific frequency bands. Increased power in low frequency band was associated with reports of higher subjective sleepinesss in some subjects. Analyses of other participants data are currently underway.

Hernandez, Norma↗
NASA NTRS2018

The Origins Space Telescope Cryo-Thermal Architecture

The Origins Space Telescope (OST) is studied as a future Mid- and Far-Infrared flagship-class observatory. OST will cover the wavelength range from 6 to 600 microns. To reach the sky background for 200-micron wavelengths temperatures of 4 degrees Kelvin or lower are required. To achieve this low temperature active cooling is required, along with passive shielding and passive radiation to deep space. Currently two concepts are being studied: Concept 1 with a 9-meter-diameter primary and a suite of 5 extremely capable instruments providing both imaging and spectroscopy over the entire wavelength range. Concept 2 is a more modest sized telescope with a collecting area equivalent to a 5-meter primary, fewer deployments and 3 or 4 instruments also covering the entire wavelength range for imaging and spectroscopy, although with somewhat reduced spectroscopic resolution, and somewhat slower mapping speed. This paper will describe OST Concept 2's cryogenic thermal architecture and thermal model results.

Space Telescope↗
NASA NTRS2020

MODIS TEB Calibration Algorithm Improvements for Future L1B Collection

Terra and Aqua MODIS have provided continuous global observations for scientific applications for more than 20 and 18 years, respectively. The radiometric calibration of the MODIS thermal emissive bands (TEB) is based on a quadratic approximation of the instrument response. The calibration coefficients look-up tables (LUTs) are updated using the response of the MODIS on-board blackbody (BB)with the response background subtracted by space view. The quarterly on-board BB warm-up and cool-down activity temperature ranges from 270 K to 315 K, and the derived offset has a relatively large uncertainty. Electronic cross-talk, an artifact that affects both instrument calibration and Earth view (EV) radiance retrievals, is corrected based on lunar observations. Calibration assessments using EV observations (e.g. ocean, desert, Antarctic Dome Concordia, and deep convective clouds) provide useful information to evaluate the impact of the Terra safe mode (February 2016) and Aqua MODIS formatter reset (January 2018) events on both MODIS instruments. This study focuses on the TEB radiometric calibration algorithm improvements for future collections based on calibration assessments using EV measurements and analytical modeling. Measurement stability and consistency over specific Earth scenes with a wide temperature range, as well as their brightness temperature (BT) dependency, are used for bias estimations in the calibration coefficients. Calibration coefficients are derived and updated after adjusting the current fitting algorithm. Thereafter, using the test LUTs, their impact on the Level 1B (L1B) data for different EV scenes is analyzed.

MODIS↗
NASA NTRS2023

Evaluation of the Interference of Tenax®TA Adsorbent With Dimethylformamide Dimethyl Acetal Reagent for Gas Chromatography-Dragonfly Mass Spectrometry and Future Gas Chromatography-Mass Spectrometry in Situ Analysis

Among future space missions, national aeronautics and space administration (NASA) selected two of them to analyze the diversity in organic content within Martian and Titan soil samples using a gas chromatograph – mass spectrometer (GC–MS) instrument. The Dragonfly space mission is planned to be launched in 2027 to Titan's surface and explore the Shangri-La surface region for years. One of the main goals of this mission is to understand the past and actual abundant prebiotic chemistry on Titan, which is not well characterized yet. The ExoMars space mission is planned to be launched in 2028 to Mars’ surface and explore the Oxia Planum and Mawrth Vallis region for years. The main objectives focus on the exploration of the subsurface soil samples, potentially richer in organics, that might be relevant for the search of past life traces on Mars where irradiation does not impact the matrices and organics. One recently used sample pre-treatment for gas chromatography – mass spectrometry analysis is planned on both space missions to detect refractory organic molecules of interest for astrobiology. This pre-treatment is called derivatization and uses a chemical reagent – called dimethylformamide dimethyl acetal (DMF-DMA) – to sublimate organic compounds keeping them safe from thermal degradation and conserving the chirality of the molecules extracted from Titan or Mars’ matrices. Indeed, the detection of building blocks of life or enantiomeric excess of some organics (e.g. amino acids) after DMF-DMA pre-treatment and GC–MS analyses would be both bioindicators. The main results highlighted by our work on DMF-DMA and Tenax®TA interaction and efficiency to detect organic compounds at ppb levels in a fast and single preparation are first that Tenax®TA did not show the onset of degradation until after 150 experiments – a 120 h at 300 °C experiment – which greatly exceeds the experimental lifetimes for the DraMS and GC-space in situ investigations. Tenax®TA polymer and DMF-DMA produce many by-products (about 70 and 46, respectively, depending on the activation temperature). Further, the interaction between the two leads to the production of 22 additional by-products from DMF-DMA degradation, but these listed by-products do not prevent the detection of trace-level organic molecules after their efficient derivatization and volatilization by DMF-DMA in the oven ahead the GC–MS trap and column.

DraMS-Dragonfly mission↗
NASA NTRS1978

Effects of long-period solar activity fluctuation on temperature and pressure of the terrestrial atmosphere

The present state of research on the influence of solar sunspot activity on tropospheric temperature and pressure is reviewed. The existence of an 11-year temperature cycle of 5 different types is affirmed. A cyclic change in atmospheric pressure, deducing characteristic changes between 11-year cycles is discussed. The existence of 80-year and 5-to-6-year cycles of temperature is established, and physical causes for birth are suggested.

Rubashev, B. M.↗
NASA NTRS1977

Loss of circadian rhythmicity in body temperature and locomotor activity following suprachiasmatic lesions in the rat

In experiments on male and female ambulatory rats, the effect of bilateral suprachiasmatic lesions on deep body temperature and locomotor activity circadian rhythms was investigated. A L/D:12/12 cycle and 23 C ambient temperature were maintained. One-half of the rats received radiofrequency lesions in the suprachiasmic nucleus (SCN) while the second group were sham operated by lowering the radiofrequency electrode to the SCN without producing electrolytic lesions. Four weeks were allowed for recuperation. Autopsies were conducted to make sure that the lesions were restricted to SCN. The results show the complete disappearance of circadian rhythm in the SCN lesioned rats and only a slight diminution for the sham operated rats.

Saleh, M. A.↗
NASA NTRS1981

The distribution of maximum temperatures of coronal active region loops

Starting with the integrated emission measure distributions of solar active regions, the distribution of the maximum temperature parameter which characterizes individual plasma loops is determined. The observed emission measure distributions were determined by combining EUV and X-ray data from two separate experiments on ATM/Skylab. The present work sets some limits on such an approach. It is found that the distribution of maximum temperature has approximately the same shape as the integrated emission measure distributions, a result which is expected since most of the loop emission measure is near their maximum temperatures.

Teske, R. G.↗
NASA NTRS1992

Stress versus temperature dependence of activation energies for creep

The activation energy for creep at low stresses and elevated temperatures is associated with lattice diffusion, where the rate controlling mechanism for deformation is dislocation climb. At higher stresses and intermediate temperatures, the rate controlling mechanism changes from dislocation climb to obstacle-controlled dislocation glide. Along with this change in deformation mechanism occurs a change in the activation energy. When the rate controlling mechanism for deformation is obstacle-controlled dislocation glide, it is shown that a temperature-dependent Gibbs free energy does better than a stress-dependent Gibbs free energy in correlating steady-state creep data for both copper and LiF-22mol percent CaF2 hypereutectic salt.

Freed, A. D.↗
NASA NTRS1990

Solar activity variation of ionospheric plasma temperatures

The present status of understanding and modeling of the variation of electron and ion temperatures with solar activity is reviewed. All atmospheric and ionospheric densities and temperatures are positively correlated with solar activity except the electron temperature, which exhibits a rather complex variation pattern during a solar cycle. The ion temperature at low altitudes closely follows the variation patterns of the neutral temperature. The electron temperature at high altitudes increases with increasing solar activity; the increase is larger during day than during night and exhibits a latitudinal variation. At low altitudes during daytime, tha amplitude of the seasonal variation of the electron temperature increases toward the solar maximum. At 400 km during daytime, the summer electron temperatures for Millstone Hill increase slightly toward higher solar activities, whereas the winter temperatures decrease distinctly. For Arecibo, an opposite trend is noticeable.

Bilitza, D.↗
NASA NTRS1971

Temperature adaptation of active sodium-potassium transport and of passive permeability in erythrocytes of ground squirrels.

Unidirectional active and passive fluxes of K-42 and Na-24 were measured in red blood cells of ground squirrels (hibernators) and guinea pigs (nonhibernators). As the temperature was lowered, ?active' (ouabain-sensitive) K influx and Na efflux were more considerably diminished in guinea pig cells than in those of ground squirrels. The fraction of total K influx which is ouabain-sensitive in red blood cells of ground squirrels was virtually constant at all temperatures, whereas it decreased abruptly in guinea pig cells as temperature was lowered.

Kimzey, S. L.↗
NASA NTRS1985

Measured response of the equatorial thermospheric temperature to geomagnetic activity and solar flux changes

Fabry-Perot inteferometer determinations of thermospheric temperatures from 630.0-nm nightglow line-width measurements have been carried out for the period April-August 1983 from Arequipa, Peru (16.4-deg S, 71.5-deg W geographic; 4.4-deg S magnetic). The nightly variation of the thermospheric temperature T(n) measured on 62 nights is compared with MSIS model predictions and found to agree occasionally with the model but, on average, to exceed model predictions by about 180 K. The largest differences, 400-500 K, often occur during strongly increasing geomagnetic activity such as sudden commencements. The rapid increases in T(n) may result from energetic neutrals precipitating at low latitudes from the ring current or from energy carried to equatorial regions from high-latitude (auroral oval) heat sources by gravity waves and equatorward neutral winds.

Biondi, M. A.↗
DOE OSTI2025

Low-temperature access to active iron and iron/nickel nitrides as potential electrocatalysts for the oxygen evolution reaction

Low-temperature, scalable routes to transition metal nitride (TMN) nanoparticles are desirable for a wide range of applications, yet their synthesis typically requires high temperatures (>350 °C) and reactive gas environments (e.g., NH 3 or H 2 /N 2 ). Here, we report a colloidal synthesis of mono- and bimetallic TMN nanoparticles using preformed metal carbonyl clusters as precursors and urea or diethylenetriamine (DETA) as nitrogen sources. This strategy enables access to size-controlled, phase-pure ε-Fe 3 N x and Fe y Ni 3−y N nanoparticles at temperatures below 300 °C, without the need for flowing reactive gas atmospheres. By systematically varying nitrogen precursor, reaction temperature, and cluster identity, we achieve tunable nitrogen stoichiometry (x) and phase selectivity between N-rich and N-poor TMNs. Structural and magnetic characterization confirms clean decomposition of the precursors and phase formation consistent with controlled nitridation at the nanoscale. Preliminary electrochemical measurements in alkaline media demonstrate that these materials exhibit oxygen evolution reaction (OER) overpotentials comparable to RuO 2 , highlighting their viability for future electrocatalytic applications.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Understanding the Origin of Negative Temperature Dependence and Activity of N-Coordinated Cobalt Sites During Ethylene Dimerization

The on-demand production of short-chain linear alpha olefins (LAOs; C4-C8) via C2H4 dimerization and oligomerization is industrially attractive, prompting extensive research on designing active, selective, and stable catalysts for industrial use. Cobalt supported on ammoniated carbon (Co(NH3)x/C) catalysts have shown remarkable activity and selectivity in this process. However, critical aspects such as the active phase, active site structure, the role of the catalyst support, cobalt loading effects, and the inverse correlation of the reaction rate with temperature remain inadequately understood. This study systematically explores these factors using a combination of steady-state differential catalytic tests, in situ molecular characterization including diffuse reflectance UV-Vis (DR-UV-Vis), Infrared, and Raman spectroscopies, and ex situ X-ray diffraction (XRD) and high annular aberration-corrected dark field transmission electron microscopy (HAADF-STEM). Various supports (SiO2, Al2O3, NH4-ZSM-5, g-C3N4, and C) and cobalt loadings (1.0-3.0 Co nm-2) were studied to determine the optimal catalyst composition and identify the active phase and sites. Carbon-supported catalysts uniquely produce C4-8 LAOs during C2H4 dimerization, with site-time-yield remaining constant (~10-3 s-1) for 1.0-4.0 Co nm-2 at prolonged reaction times (24-48?h time-on-stream). At higher loadings of 6.0 Co nm-2, the formation of crystalline CoO and Co3O4 phases reduces catalytic activity and LAO selectivity. Our findings show that active catalysts lack crystalline cobalt oxides and instead feature dispersed Co2+ sites, tetra-coordinated to a mix of N/NH3 and O/H2O ligands, which catalyze C2H4 dimerization via the Cossee-Arlman mechanism, exhibiting 1st order dependence on C2H4 concentration. The observed inverse rate-temperature correlation is attributed to compensation effects (i.e., presence of Cremer-Constable relationship) linked to changes in adsorption enthalpic and entropic factors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗