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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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NASA NTRS2016

Pluto is the new Mars!

Data from NASA's New Horizons encounter with Pluto in July 2015 revealed an astoundingly complex world. The surface seen on the encounter hemisphere ranged in age from ancient to recent. A vast craterless plain of slowly convecting solid nitrogen resides in a deep primordial impact basin, reminiscent of young enigmatic deposits in Mars' Hellas basin. Like Mars, regions of Pluto are dominated by valleys, though the Pluto valleys are thought to be carved by nitrogen glaciers. Pluto has fretted terrain and halo craters. Pluto is cut by tectonics of several different ages. Like Mars, vast tracts on Pluto are mantled by dust and volatiles. Just as on Mars, Pluto has landscapes that systematically vary with latitude due to past and present seasonal (and mega-seasonal) effects on two major volatiles. On Mars, those volatiles are H2O and CO2; on Pluto they are CH4 and N2. Like Mars, some landscapes on Pluto defy easy explanation. In the Plutonian arctic there is a region of large (approx. 40 km across) deep (approx. 3-4 km) pits that probably could not be formed by sublimation, or any other single process, alone. Equally bizarre is the Bladed terrain, which is composed of fields of often roughly aligned blade-like ridges covering the flanks and crests of broad regional swells. Topping the unexpected are two large mounds approximately150 km across, approx. 5-6 km high, with great central depressions at their summits. The central depressions are almost as deep as the mounds are tall. These mounds have many of the characteristics of volcanic mountains seen on Mars and elsewhere in the inner solar system. Hypotheses for the formation of these Plutonian mounds so far all have challenges, principally revolving around the need for H2O ice to support their relief and the difficulty imagining mechanisms that would mobilize H2O. From the perspective of one year after the encounter, our appreciation of the extent of Pluto's diversity and complexity is quite reminiscent of the perspective the science community had of Mars, with similar quality data sets, soon after the early reconnaissance of that planet in the late 1960s and early 70s. So certainly in this sense, Pluto is the new Mars.

Pluto↗
NASA NTRS2003

Going Places No Infrared Temperature Devices Have Gone Before

Exergen's IRt/c is a self-powered sensor that matches a thermocouple within specified temperature ranges and provides a predictable and repeatable signal outside of this specified range. Possessing an extremely fast time constant, the infrared technology allows users to measure product temperature without touching the product. The IRt/c uses a device called a thermopile to measure temperature and generate current. Traditionally, these devices are not available in a size that would be compatible with the Exergen IRt/c, based on NASA s quarterinch specifications. After going through five circuit designs to find a thermopile that would suit the IRt/c design and match the signal needed for output, Exergen maintains that it developed a model that totaled just 20 percent of the volume of the previous smallest detector in the world. Following completion of the project with Glenn, Exergen continued development of the IRt/c for other customers, spinning off a new product line called the micro IRt/c. This latest development has broadened applications for industries that previously could not use infrared thermometers due to size constraints. The first commercial use of the micro IRt/c involved an original equipment manufacturer that makes laminating machinery consisting of heated rollers in very tight spots. Accurate temperature measurement for this application requires close proximity to the heated rollers. With the micro IRt/c s 50-millisecond time constant, the manufacturer is able to gain closer access to the intended temperature targets for exact readings, thereby increasing productivity and staying ahead of competition.In a separate application, the infrared temperature sensor is being utilized for avalanche warnings in Switzerland. The IRt/c is mounted about 5 meters above the ground to measure the snow cover throughout the mountainous regions of the country.

Source record↗
NASA NTRS2012

Analysis of Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption During the ASCENDS 2009-2011 Airborne Campaigns

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission and have demonstrated the CO2 and O2 measurements from aircraft. Our technique uses two pulsed lasers allowing simultaneous measurement of a single CO2 absorption line near 1572 nm, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are stepped in wavelength across the CO2 line and an O2 line doublet during the measurement. The column densities for the CO2 and O2 are estimated from the differential optical depths (DOD) of the scanned absorption lines via the IPDA technique. For the 2009 ASCENDS campaign we flew the CO2 lidar on a Lear-25 aircraft, and measured the absorption line shapes of the CO2 line using 20 wavelength samples per scan. Measurements were made at stepped altitudes from 3 to 12.6 km over the Lamont OK, central Illinois, North Carolina, and over the Virginia Eastern Shore. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We averaged every 10 seconds of measurements and used a cross-correlation approach to estimate the range to the scattering surface and the echo pulse energy at each wavelength. We then solved for the best-fit CO2 absorption line shape, and calculated the DOD of the fitted CO2 line, and computed its statistics at the various altitude steps. We compared them to CO2 optical depths calculated from spectroscopy based on HITRAN 2008 and the column number densities calculated from the airborne in-situ readings. The 2009 measurements have been analyzed and they were similar on all flights. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. They showed the expected nearly the linear dependence of DOD vs altitude. The measurements showed ~ 1 ppm random errors for 8-10 km altitudes and ~30 sec averaging times. For the 2010 ASCENDS campaigns we flew the CO2lidar on the NASA DC-8 and added an 02lidar channel. During July 2010 we made measurements of CO2 and O2 column absorption during longer flights over Railroad Valley NV, the Pacific Ocean and over Lamont OK. CO2 measurements were made with 30 steps/scan, 300 scans/sec and improved line resolution and receiver sensitivity. Analysis of the 2010 CO2 measurements shows the expected ~linear change of DOD with altitude. For measurements at altitudes> 6 km the random errors were 0.3 ppm for 80 sec averaging times. For the summer 2011 ASCENDS campaigns we made further improvements to the lidar's CO2 line scan and receiver sensitivity. We demonstrated measurements over the California Central Valley, to stratus cloud tops over the Pacific Ocean, over mountain regions with snow, and over several areas with broken clouds. Details of the lidar measurements and their analysis will be described in the presentation.

Abshire, J. B.↗
NASA NTRS1995

Stratospheric Ozone Intercomparison Campaign (STOIC) 1989: Overview

The NASA Upper Atmosphere Research Program organized a Stratospheric Ozone Intercomparison Campaign (STOIC) held in July-August 1989 at the Table Mountain Facility (TMF) of the Jet Propulsion Laboratory (JPL). The primary instruments participating in this campaign were several that had been developed by NASA for the Network for the Detection of Stratospheric Change: the JPL ozone lidar at TMF, the Goddard Space Flight Center trailer-mounted ozone lidar which was moved to TMF for this comparison, and the Millitech/LaRC microwave radiometer. To assess the performance of these new instruments, a validation/intercomparison campaign was undertaken using established techniques: balloon ozonesondes launched by personnel from the Wallops Flight Facility and from NOAA Geophysical Monitoring for Climate Change (GMCC) (now Climate Monitoring and Diagnostics Laboratory), a NOAA GMCC Dobson spectrophotometer, and a Brewer spectrometer from the Atmospheric Environment Service of Canada, both being used for column as well as Umkehr profile retrievals. All of these instruments were located at TMF and measurements were made as close together in time as possible to minimize atmospheric variability as a factor in the comparisons. Daytime rocket measurements of ozone were made by Wallops Flight Facility personnel using ROCOZ-A instruments launched from San Nicholas Island. The entire campaign was conducted as a blind intercomparison, with the investigators not seeing each others data until all data had been submitted to a referee and archived at the end of the 2-week period (July 20 to August 2, 1989). Satellite data were also obtained from the Stratospheric Aerosol and Gas Experiment (SAGE 2) aboard the Earth Radiation Budget Satellite and the Total Ozone Mapping Spectrometer (TOMS) aboard Nimbus 7. An examination of the data has found excellent agreement among the techniques, especially in the 20- to 40-km range. As expected, there was little atmospheric variability during the intercomparison, allowing for detailed statistical comparisons at a high level of precision. This overview paper summarizes the campaign and provides a 'road map' to subsequent papers in this issue by the individual instrument teams which will present more detailed analysis of the data and conclusions.

Margitan, J. J.↗
NASA NTRS1999

Thorium Enrichment within the Procellarum KREEP Terrane: The Record in Surface Deposits and Significance for Thermal Evolution

The nearside-farside structural and compositional asymmetry of the Moon was recognized during the early days of Apollo and the suggestion was made that the migration of mantle melts to the nearside would have been favored by early Earth-Moon orbital dynamics and nonuniform planetesimal bombardment. Recent global geochemical mapping by Lunar Prospector has provided additional data, particularly in the Th distribution, that strongly supports the notion of global, preferential melt migration, which led in part to the development of the Procellarum KREEP Terrane (PKT) [2-5]. The surface distribution of Th was then reshaped by basin-forming impacts into the PKT, especially the Imbrium impact, which was the last and largest to strike in that region. The Imbrium event probably excavated material from a partially molten zone deep in the crust and delivered Th-rich ejecta Moon-wide. A fundamentally important but poorly understood aspect of the global Th distribution is the concentration of Th in the subsurface rocks of the PKT crustal section. For example, depending on what assumptions are made, the PKT crustal section, which is about 12% of the crust and only about 1.2% of the whole Moon, may contain as much as 40% of the Moon's entire Th budget. Such a distribution of Th and related heat-producing elements would have had a profound effect on melting, mixing, and the thermal evolution of the PKT and the underlying mantle. In this abstract, we examine the compositions of terra formations within the PKT and relate them to some of the Th-bearing rock types known from the Apollo samples. It appears that the existence of the PKT may be a unifying concept for a number of petrologic and geochemical observations. From the initial Lunar Prospector gamma-ray spectrometer data(-about 5 deg. resolution) and from the preliminary low-orbit data, there appears to be a number of relatively hotter "spots" within the PKT in terms of Th concentration. Some of the hotter spots correspond to intermediate-sized craters that penetrated volcanic flows and excavated Th-rich, submare material, such as Aristarchus, Aristillus, and Kepler. Other spots, however, correspond to surficial formations that constitute mainly rough topography associated with Imbrium ejecta or circum-Imbrium ring mountains and do not necessarily imply the presence of exposed KREEP basalts. The Fra Mauro Formation south of Copernicus toward the Apollo 14 site and regions of the Alpes Formation southwest of Copernicus in the vicinity of Reinhold lie within the most prominent hotspot; here them concentration is consistent with that found in the Apollo 14 soils (about 12-13 ppm) when the proportions of Fra Mauro Formation and mare basalt are considered. The area between Copernicus and Kepler and northwest of Copernicus in terra extending to the Carpathians is similarly enriched in Th. The Apennines from Eratosthenes toward the Apollo 15 site contain elevated Th concentrations, as does the northwestern quadrant of circum-Imbrium terra, especially between (but not including) La Condamine and Plato, and in the region northwest of the Jura mountains extending southward past Mairan to the Gruithuisen-Domes region. Within the main topographic rim of Imbrium, the Apennine Bench formation south of Archimedes appears to have relatively elevated Th concentration. Comparing the map of Th distribution to a digital-elevation map derived from Clementine altimetry, it appears that most of the areas richest in Th occur where the surface is elevated relative to the majority of PKT volcanic plains. Not all rough topography within the PKT has such elevated Th, however. Based on an analysis of the 5 deg. data, and using the calibration of, the mean Th concentrations for mainly volcanic-resurfaced terrain and rugged terrain are similar (about 5.5 ppm). This occurs in part because craters that penetrated mare basalt excavated Th-rich material. Even so, there appear to be extensive areas of volcanic resurfacing that have no obvious extrinsic source of Th-rich material, suggesting that the basalts, themselves, may contain as much as 5-6 ppm Th. High-FeO concentrations (18 to >20 wt%) indicate that these are not KREEP basalts but mare basalts. If so, this is surprising because most of the Apollo-sampled mare basalts have very low-Th (typically <2 ppm). A variety of Th-rich materials occur in the sample collection, particularly in the samples from the Apollo 12,14, and 15 sites. The most abundant Th-rich rock types are the mafic impact-melt breccias, which although found at all sites, are most abundant at Apollo 14, where they dominate the rock samples and make up some 40% of the rock particles in the soil. These have Th concentrations ranging up to about 30 ppm and averaging about 18 ppm. The Apollo 14 soils contain about 13 ppm Th, reflecting the high abundance of this melt-breccia component. At the nearby Apollo 12 site, the rocks consist mainly of mare basalts, and these have low-Th concentrations, mostly <1 ppm. Among the nonmare rocks, however, a few such as complex breccia 12013 contain a variety of evolved lithologies and represent potential sources of Th-rich components ranging from 17 to 50 ppm. A single fragment of KREEP basalt from the Apollo 12 soil contains about 50 ppm Th. Despite the identification of highly Th-enriched lithologic components at the Apollo 12 site, the soils there vary linearly in composition so as to extrapolate to a moderate Th KREEP-basalt component or a composition like that of the Fra Mauro formation as reflected by Apollo 14 soil (14 ppm Th at 10 wt% FeO). The nearby Lansberg Crater (39-km diameter) is a likely candidate to have delivered submare material such as buried Fra Mauro or Alpes material to the Apollo 12 site. Additional information contained in the original.

Jolliff, B. L.↗
NASA NTRS2013

Reflectance Spectra Diversity of Silica-Rich Materials: Sensitivity to Environment and Implications for Detections on Mars

Hydrated silica-rich materials have recently been discovered on the surface of Mars by the Mars Exploration Rover (MER) Spirit, the Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), and the Mars Express Observatoire pour la Mineralogie, l'Eau, les Glaces, et l'Activite'(OMEGA) in several locations. Having been interpreted as hydrothermal deposits and aqueous alteration products, these materials have important implications for the history of water on the martian surface. Spectral detections of these materials in visible to near infrared (Vis NIR) wavelengths have been based on a H2O absorption feature in the 934-1009 nm region seen with Spirit s Pancam instrument, and on SiOH absorption features in the 2.21-2.26 micron range seen with CRISM. Our work aims to determine how the spectral reflectance properties of silica-rich materials in Vis NIR wavelengths vary as a function of environmental conditions and formation. Here we present laboratory reflectance spectra of a diverse suite of silica-rich materials (chert, opal, quartz, natural sinters and synthetic silica) under a range of grain sizes and temperature, pressure, and humidity conditions. We find that the H2O content and form of H2O/OH present in silica-rich materials can have significant effects on their Vis NIR spectra. Our main findings are that the position of the approx.1.4 microns OH feature and the symmetry of the approx.1.9 microns feature can be used to discern between various forms of silica-rich materials, and that the ratio of the approx.2.2 microns (SiOH) and approx.1.9 microns (H2O) band depths can aid in distinguishing between silica phases (opal-A vs. opal-CT) and formation conditions (low vs. high temperature). In a case study of hydrated silica outcrops in Valles Marineris, we show that careful application of a modified version of these spectral parameters to orbital near-infrared spectra (e.g., from CRISM and OMEGA) can aid in characterizing the compositional diversity of silica-bearing deposits on Mars. We also discuss how these results can aid in the interpretation of silica detections on Mars made by the MER Panoramic Camera (Pancam) and Mars Science Laboratory (MSL) Mast-mounted Camera (Mastcam) instruments.

Rice, M. S.↗
NASA NTRS2006

Observations of Precipitation Size and Fall Speed Characteristics within Coexisting Rain and Wet Snow

Ground-based measurements of particle size and fall speed distributions using a Particle Size and Velocity (PARSIVEL) disdrometer are compa red among samples obtained in mixed precipitation (rain and wet snow) and rain in the Oregon Cascade Mountains and in dry snow in the Rock y Mountains of Colorado. Coexisting rain and snow particles are distinguished using a classification method based on their size and fall sp eed properties. The bimodal distribution of the particles' joint fall speed-size characteristics at air temperatures from 0.5 to 0 C suggests that wet-snow particles quickly make a transition to rain once mel ting has progressed sufficiently. As air temperatures increase to 1.5 C, the reduction in the number of very large aggregates with a diame ter > 10 mm coincides with the appearance of rain particles larger than 6 mm. In this setting. very large raindrops appear to be the result of aggregates melting with minimal breakup rather than formation by c oalescence. In contrast to dry snow and rain, the fall speed for wet snow has a much weaker correlation between increasing size and increasing fall speed. Wet snow has a larger standard deviation of fall spee d (120%-230% relative to dry snow) for a given particle size. The ave rage fall speed for observed wet-snow particles with a diameter great er than or equal to 2.4 mm is 2 m/s with a standard deviation of 0.8 m/s. The large standard deviation is likely related to the coexistence of particles of similar physical size with different percentages of melting. These results suggest that different particle sizes are not required for aggregation since wet-snow particles of the same size can have different fall speeds. Given the large standard deviation of fa ll speeds in wet snow, the collision efficiency for wet snow is likely larger than that of dry snow. For particle sizes between 1 and 10 mm in diameter within mixed precipitation, rain constituted I % of the particles by volume within the isothermal layer at 0 C and 4% of the particles by volume for the region just below the isothermal layer where air temperatures rise from 0" to 0.5"C. As air temperatures increa sed above 0.5 C, the relative proportions of rain versus snow particl es shift dramatically and raindrops become dominant. The value of 0.5 C for the sharp transition in volume fraction from snow to rain is sl ightly lower than the range from 1 .l to 1.7 C often used in hydrolog ical models.

Yuter, Sandra E.↗
NASA NTRS2023

Characterization of Errors in Satellite-Based HCHO/NO 2 Tropospheric Column Ratios With Respect to Chemistry, Column-to-PBL Translation, Spatial Representation, and Retrieval Uncertainties

The availability of formaldehyde (HCHO) (a proxy for volatile organic compound reactivity) and nitrogen dioxide (NO 2 ) (a proxy for nitrogen oxides) tropospheric columns from ultraviolet–visible (UV–Vis) satellites has motivated many to use their ratios to gain some insights into the near-surface ozone sensitivity. Strong emphasis has been placed on the challenges that come with transforming what is being observed in the tropospheric column to what is actually in the planetary boundary layer (PBL) and near the surface; however, little attention has been paid to other sources of error such as chemistry, spatial representation, and retrieval uncertainties. Here we leverage a wide spectrum of tools and data to quantify those errors carefully. Concerning the chemistry error, a well-characterized box model constrained by more than 500 h of aircraft data from NASA's air quality campaigns is used to simulate the ratio of the chemical loss of HO 2 + RO 2 (LRO x ) to the chemical loss of NO x (LNO x ). Subsequently, we challenge the predictive power of HCHO/NO 2 ratios (FNRs), which are commonly applied in current research, in detecting the underlying ozone regimes by comparing them to LRO x /LNO x . FNRs show a strongly linear (R 2 =0.94) relationship with LRO x /LNO x , but only on the logarithmic scale. Following the baseline (i.e., ln(LRO x /LNO x ) = −1.0 ± 0.2) with the model and mechanism (CB06, r2) used for segregating NO x -sensitive from VOC-sensitive regimes, we observe a broad range of FNR thresholds ranging from 1 to 4. The transitioning ratios strictly follow a Gaussian distribution with a mean and standard deviation of 1.8 and 0.4, respectively. This implies that the FNR has an inherent 20 % standard error (1σ) resulting from not accurately describing the RO x –HO x cycle. We calculate high ozone production rates (PO 3 ) dominated by large HCHO × NO 2 concentration levels, a new proxy for the abundance of ozone precursors. The relationship between PO 3 and HCHO × NO 2 becomes more pronounced when moving towards NO x -sensitive regions due to nonlinear chemistry; our results indicate that there is fruitful information in the HCHO × NO 2 metric that has not been utilized in ozone studies. The vast amount of vertical information on HCHO and NO 2 concentrations from the air quality campaigns enables us to parameterize the vertical shapes of FNRs using a second-order rational function permitting an analytical solution for an altitude adjustment factor to partition the tropospheric columns into the PBL region. We propose a mathematical solution to the spatial representation error based on modeling isotropic semivariograms. Based on summertime-averaged data, the Ozone Monitoring Instrument (OMI) loses 12 % of its spatial information at its native resolution with respect to a high-resolution sensor like the TROPOspheric Monitoring Instrument (TROPOMI) (> 5.5 × 3.5 km 2 ). A pixel with a grid size of 216 km 2 fails at capturing ∼ 65 % of the spatial information in FNRs at a 50 km length scale comparable to the size of a large urban center (e.g., Los Angeles). We ultimately leverage a large suite of in situ and ground-based remote sensing measurements to draw the error distributions of daily TROPOMI and OMI tropospheric NO 2 and HCHO columns. At a 68 % confidence interval (1σ), errors pertaining to daily TROPOMI observations, either HCHO or tropospheric NO 2 columns, should be above 1.2–1.5 × 10 16 molec. cm −2 to attain a 20 %–30 % standard error in the ratio. This level of error is almost non-achievable with the OMI given its large error in HCHO. The satellite column retrieval error is the largest contributor to the total error (40 %–90 %) in the FNRs. Due to a stronger signal in cities, the total relative error (< 50 %) tends to be mild, whereas areas with low vegetation and anthropogenic sources (e.g., the Rocky Mountains) are markedly uncertain (> 100 %). Our study suggests that continuing development in the retrieval algorithm and sensor design and calibration is essential to be able to advance the application of FNRs beyond a qualitative metric.

Amir H. Souri↗