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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 NTRS2013

Reference Images from Thin Sections of Lunar Regolith

The specialist literature about the lunar regolith is massive. It is also highly focused on specific topics and effectively impenetrable to most non-geologists. Both characteristics of the literature present substantial hurdles to scientists and engineers interested in the regolith In the author's experience it neither surprising or unusual to find serious misconceptions about lunar-type materials outside of the lunar research community. Education of professionals who are non-geologists but interested in the regolith is impeded by a lack of some basic resources. One asset that has been missing is simply detailed images of the regolith "soil". While a few websites offer imagery of specific features, these are of course selected to illustrate specific features. It is almost impossible for a non-specialist to reason from these what "normal" or "typical" regolith looks like. Further, access to lunar material is highly restricted. And as publications rarely do not provide other than highly focused and narrowly tailored data, there is little potential for workers without personal access to sample to do any work with lunar material. To address both problems the authors have begun to make high resolution optical micrographs of entire thin sections of lunar regolith.

Rickman Doug↗
NASA NTRS2014

Comet C2012 S1 (ISON)s Carbon-rich and Micron-size-dominated Coma Dust

Comet C/2012 S1 (ISON) was unique in that it was a dynamically new comet derived from the Nearly Isotropic Oort cloud reservoir of comets with a sun-grazing orbit. We present thermal models for comet ISON (rh approx.1.15 AU, 2013-Oct-25 11:30 UT) that reveal comet ISON's dust was carbon-rich and dominated by a narrow size distribution dominated by approx. micron-sized grains. We constrained the models by our SOFIA FORCAST photometry at 11.1, 19.7 and 31.5 microns and by a silicate feature strength of approx.1.1 and an 8-13microns continuum greybody color temperature of approx. 275-280 K (using Tbb ∝ r−0.5 h and Tbb approx. 260-265 K from Subaru COMICS, 2013-Oct-19 UT)[1,2]. N-band spectra of comet ISON with the BASS instrument on the NASA IRTF (2013-Nov-11-12 UT) show a silicate feature strength of approx. 1.1 and an 11.2microns forsterite peak.[3] Our thermal models yield constraints the dust composition as well as grain size distribution parameters: slope, peak grain size, porosity. Specifically, ISON's dust has a low silicate-to- amorphous carbon ratio (approx. 1:9), and the coma size distribution has a steep slope (N4.5) such that the coma is dominated by micron-sized, moderately porous, carbon-rich dust grains. The N-band continuum color temperature implies submicronto micron-size grains and the steep fall off of the SOFIA far-IR photometry requires the size distribution to have fewer relative numbers of larger and cooler grains compared to smaller and hotter grains. A proxy for the dust production rate is fρ approx.1500 cm, akin to Afρ. ISON has a moderate-to-low dust-to-gas ratio. Comet ISON's dust grain size distribution does not appear similar to the few well-studied long-period Nearly Isotropic Comets (NICs), namely C/1995 O1 (Hale-Bopp) and C/2001 Q4 (NEAT) that had smaller and/or more highly porous grains and larger sizes, or C/2007 N4 (Lulin) and C/2006 P1 (McNaught) that had large and/or compact grains. Radial transport to comet-forming disk distances (≥ 20 AU) is easier for smaller grains (≤1 micron) than for larger grains (approx. 20 microns like Stardust terminal particles). The presence of predominantly micron-sized and smaller grains suggests comet ISON may have formed either earlier in disk evolution whereby larger grains did not have the time to be transported to distances beyond Neptune, or the comet formed so far out in the disk that larger grains did not traverse such large radial distances. The high carbon-content of ISON's refractory dust appears to be complimented by the presence of limitedlifetime organic (CHON-like) grain materials: preliminary analyses of near-IR and high-resolution optical spectra indicate that gas-phase daughter molecules C2, CN, and CH were more abundant than their parent molecules (C2H2, C2H6, measured in the near- IR). Dust composition as well as grain size distribution parameters (slope, peak grain size, and porosity) give clues to comet origins.

NASA/DLR Stratospheric Observatory↗
NASA NTRS2014

Investigation into the Use of the Concept Laser QM System as an In-Situ Research and Evaluation Tool

The NASA Marshall Space Flight Center (MSFC) is using a Concept Laser Fusing (Cusing) M2 powder bed additive manufacturing system for the build of space flight prototypes and hardware. NASA MSFC is collecting and analyzing data from the M2 QM Meltpool and QM Coating systems for builds. This data is intended to aide in understanding of the powder-bed additive manufacturing process, and in the development of a thermal model for the process. The QM systems are marketed by Concept Laser GmbH as in-situ quality management modules. The QM Meltpool system uses both a high-speed near-IR camera and a photodiode to monitor the melt pool generated by the laser. The software determines from the camera images the size of the melt pool. The camera also measures the integrated intensity of the IR radiation, and the photodiode gives an intensity value based on the brightness of the melt pool. The QM coating system uses a high resolution optical camera to image the surface after each layer has been formed. The objective of this investigation was to determine the adequacy of the QM Meltpool system as a research instrument for in-situ measurement of melt pool size and temperature and its applicability to NASA's objectives in (1) Developing a process thermal model and (2) Quantifying feedback measurements with the intent of meeting quality requirements or specifications. Note that Concept Laser markets the system only as capable of giving an indication of changes between builds, not as an in-situ research and evaluation tool. A secondary objective of the investigation is to determine the adequacy of the QM Coating system as an in-situ layer-wise geometry and layer quality evaluation tool.

Bagg, Stacey↗
NASA NTRS2021

Landslide Mapping Using Object-Based Image Analysis and Open Source Tools

Availability of high-resolution optical imagery and advances in image processing technologies have significantly improved our ability to map landslides. In recent years object-based image analysis (OBIA) has been gaining in popularity for landslide mapping due to its ability to incorporate spectral, textural, morphological and topographical properties. Many studies have been conducted based on commercial software. In this study, we create an open source Semi-Automatic Landslide Detection (SALaD) system utilizing OBIA and machine learning. Configured to run in Linux environment, it uses various opensource Python packages and modules. This system was tested in 575 km2 area along the Pasang Lhamu Highway, Nepal where large numbers of landslides were triggered by the 2015 Gorkha earthquake. Comparison with a manual inventory highlighted that this system was able to detect 70% of the landslide area. The speed and efficiency with which this system was able to detect landslides makes it a viable alternative to manual techniques for landslide mapping over large areas, when establishing approximate landslide locations is of prime importance.

Open source↗
NASA NTRS2021

Target Prioritization and Observing Strategies for the NEID Earth Twin Survey

NEID is a high-resolution optical spectrograph on the WIYN 3.5 m telescope at Kitt Peak National Observatory and will soon join the new generation of extreme precision radial velocity instruments in operation around the world. We plan to use the instrument to conduct the NEID Earth Twin Survey (NETS) over the course of the next 5 years, collecting hundreds of observations of some of the nearest and brightest stars in an effort to probe the regime of Earth-mass exoplanets. Even if we take advantage of the extreme instrumental precision conferred by NEID, it will be difficult to disentangle the weak (~10 cm/s) signals induced by such low-mass, long-period exoplanets from stellar noise for all but the quietest host stars. In this work, we present a set of quantitative selection metrics which we use to identify an initial NETS target list consisting of stars conducive to the detection of exoplanets in the regime of interest. We also outline a set of observing strategies with which we aim to mitigate uncertainty contributions from intrinsic stellar variability and other sources of noise.

Arvind F. Gupta↗
NASA NTRS2021

TESS Hunt for Young and Maturing Exoplanets (THYME). V. A Sub-Neptune Transiting a Young Star in a Newly Discovered 250 Myr Association

The detection and characterization of young planetary systems offer a direct path to study the processes that shape planet evolution. We report on the discovery of a sub-Neptune-sized planet orbiting the young star HD 110082 (TOI-1098). Transit events we initially detected during TESS Cycle 1 are validated with time-series photometry from Spitzer. High-contrast imaging and high-resolution, optical spectra are also obtained to characterize the stellar host and confirm the planetary nature of the transits. The host star is a late-F dwarf (M⁎ = 1.2Mꙩ) with a low-mass, M dwarf binary companion (M⁎ = 0.26Mꙩ) separated by nearly one arcminute (∼6200 au). Based on its rapid rotation and Lithium absorption, HD 110082 is young, but is not a member of any known group of young stars (despite proximity to the Octans association). To measure the age of the system, we search for coeval, phase-space neighbors and compile a sample of candidate siblings to compare with the empirical sequences of young clusters and to apply quantitative age-dating techniques. In doing so, we find that HD 110082 resides in a new young stellar association we designate MELANGE-1, with an age of 250(+50, -70) Myr. Jointly modeling the TESS and Spitzer light curves, we measure a planetary orbital period of 10.1827 days and radius of R(p) = 3.2 ± 0.1Rꚛ. HD 110082 b’s radius falls in the largest 12% of field-age systems with similar host-star mass and orbital period. This finding supports previous studies indicating that young planets have larger radii than their field-age counterparts.

TESS↗
NASA NTRS2021

TESS Hunt for Young and Maturing Exoplanets (THYME). V. A Sub-Neptune Transiting a Young Star in a Newly Discovered 250 Myr Association

The detection and characterization of young planetary systems offer a direct path to study the processes that shape planet evolution. We report on the discovery of a sub-Neptune-sized planet orbiting the young star HD 110082(TOI-1098). Transit events we initially detected during TESS Cycle 1 are validated with time-series photometry from Spitzer. High-contrast imaging and high-resolution, optical spectra are also obtained to characterize the stellar host and confirm the planetary nature of the transits. The host star is a late-F dwarf(Må=1.2Me)with a low-mass,M dwarf binary companion(Må=0.26Me)separated by nearly one arc minute(∼6200 au). Based on its rapid rotation and Lithium absorption, HD 110082 is young, but is not a member of any known group of young stars(despite proximity to the Octans association). To measure the age of the system, we search for coeval, phase-space neighbors and compile a sample of candidate siblings to compare with the empirical sequences of young clusters and to apply quantitative age-dating techniques. In doing so, we find that HD 110082 resides in a new young stellar association we designate MELANGE-1, with an age of -+ 2507050 Myr. Jointly modeling the TESS and Spitzer light curves, we measure a planetary orbital period of 10.1827 days and radius of Rp=3.2±0.1R⊕. HD 110082 b’s radius falls in the largest 12% of field age systems with similar host-star mass and orbital period. This finding supports previous studies indicating that young planets have larger radii than their field-age counterparts

Benjamin M. Tofflemire↗
NASA NTRS2022

A Dynamic Landslide Hazard Monitoring Framework for the Lower Mekong Region

The Lower Mekong region is one of the most landslide-prone areas of the world. Despite the need for dynamic characterization of landslide hazard zones within the region, it is largely understudied for several reasons. Dynamic and integrated understanding of landslide processes requires landslide inventories across the region, which have not been available previously. Computational limitations also hamper regional landslide hazard assessment, including accessing and processing remotely sensed information. Finally, open-source software and modelling packages are required to address regional landslide hazard analysis. Leveraging an open-source data-driven global Landslide Hazard Assessment for Situational Awareness model framework, this study develops a region-specific dynamic landslide hazard system leveraging satellite-based Earth observation data to assess landslide hazards across the lower Mekong region. A set of landslide inventories were prepared from high-resolution optical imagery using advanced image-processing techniques. Several static and dynamic explanatory variables (i.e., rainfall, soil moisture, slope, relief, distance to roads, distance to faults, distance to rivers) were considered during the model development phase. An extreme gradient boosting decision tree model was trained for the monsoon period of 2015–2019 and the model was evaluated with independent inventory information for the 2020 monsoon period. The model performance demonstrated considerable skill using receiver operating characteristic curve statistics, with Area Under the Curve values exceeding 0.95. The model architecture was designed to use near-real-time data, and it can be implemented in a cloud computing environment (i.e., Google Cloud Platform) for the routine assessment of landslide hazards in the Lower Mekong region. This work was developed in collaboration with scientists at the Asian Disaster Preparedness Center as part of the NASA SERVIR Program’s Mekong hub. The goal of this work is to develop a suite of tools and services on accessible open-source platforms that support and enable stakeholder communities to better assess landslide hazard and exposure at local to regional scales for decision making and planning.

Nishan Kumar Biswas↗
NASA NTRS2024

South Africa Ecological Conservation: Identifying and Mapping Riparian Areas in South Africa with Earth Observations

Riparian zones are thin strips of wetland that occur along the edges of rivers, lakes, and other water bodies. They provide many ecosystem and societal benefits such as stream bank stabilization, flood control, and habitat stability, making these zones very important areas to preserve and protect. Recognizing the need to accurately map these ecosystems in a cost-effective way, we partnered with the South African National Biodiversity Institute (SANBI) and the Biodiversity Survey of the Cape(BioSCape) to develop a GI methodology using Esri's ArcGIS Pro and data from Landsat 9 Operational Land Imager-2, Sentinel-2 Multispectral Instrument, and the Shuttle Radar Topography Mission to identify potential riparian zones (PRZ) and observed riparian vegetation(ORV) in the Southern Cape and the North West Province of South Africa to estimate the actual riparian vegetation (ARV) within those areas. Potential riparian ecosystems were calculated by utilizing a Topographic Wetness Index (TWI) and a water feature layer, while observed riparian vegetation were calculated by overlaying a Normalized Difference Vegetation Index (NDVI) and TWI. Actual Riparian Vegetation is determined by the overlap of ORV with PRZ and is done with conditional statements; ORV within PRZ is ARV. This method significantly improved a current riparian land cover classification since it combined high resolution optical imagery and topographic data. We anticipate such maps will be used by conservationists and practitioners interested in riparian monitoring and management.

Remote Sensing↗
NASA NTRS1980

Optical alignment of high resolution Fourier transform spectrometers

Remote sensing, high resolution FTS instruments often contain three primary optical subsystems: Fore-Optics, Interferometer Optics, and Post, or Detector Optics. We discuss the alignment of a double-pass FTS containing a cat's-eye retro-reflector. Also, the alignment of fore-optics containing confocal paraboloids with a reflecting field stop which relays a field image onto a camera is discussed.

Breckinridge, J. B.↗
NASA NTRS1985

High-resolution spectroscopy of the optical candidate for the X-ray transient X0331 + 53

High-resolution spectral observations of the optical candidate for the X-ray transient X0331 + 53 are presented. The data show broad hydrogen and helium emission and strong interstellar absorption corresponding to a visual extinction of about 7 mag. No photospheric absorption in the emission lines, and no radial-velocity variations greater than 0.5 km/s were found over a three-day period. It is concluded that the optical continuum does not arise at or near the primary star. As an example of the spectrographic data, a resolution profile of H-alpha emission in X0331 + 53 is provided.

Stocke, J.↗
NASA NTRS1986

A comparison of high-resolution radio and optical data for the northeast region of the Cygnus Loop

Radio observations of the northeastern part of the Cygnus Loop obtained with the VLA at 18 cm with a resolution of 4.7 arcsec are presented and discussed. In general, the brightest radio filaments match the brightest optical filaments very well, particularly those which are bright in H-alpha. The agreement in position, morphology, and relative brightness is particularly good where all four optical species are bright. However, a few bright radio features have no bright optical counterparts. The general radio and optical structure of the region can be explained by a model in which shocked interstellar clouds form filaments due to unstable cooling and compression. The features appear to be ropelike, although it is not possible to rule out that they are irregular sheets seen edge-on. A large gradation in cooling on a scale of parsecs is evidenced by the sequence of the optical species in emission, with a corresponding increase in density generally evidenced by the continuum radio emission.

Straka, W. C.↗
NASA NTRS1989

A high resolution electro-optical displacement measurement system

An improved electrooptical system has been developed to sense wind tunnel model position. The original system using 25.6 mm, 1024-element linear photodiode arrays (PDAs) is being successfully used at a NASA wind tunnel but has a limited range. A new two-channel system using 61.44 mm, 4096-element PDAs has been developed to double the range of vertical and pitch measurement and increase the resolution by 60 percent. The PDAs are illuminated by expanding the beam of a single low power helium neon laser into a collimated sheet of light. An object placed in front of the two parallel PDAs produces a shadow on the array apertures which determines the object's position or size. The system has an overall precision of 12.7 microns and + or - 0.015 degrees in linear and angular measurements.

Schott, Timothy D.↗
NASA NTRS1993

Nature's crucible: Manufacturing optical nonlinearities for high resolution, high sensitivity encoding in the compound eye of the fly, Musca domestica

The number of pixels per unit area sampling an image determines Nyquist resolution. Therefore, the highest pixel density is the goal. Unfortunately, as reduction in pixel size approaches the wavelength of light, sensitivity is lost and noise increases. Animals face the same problems and have achieved novel solutions. Emulating these solutions offers potentially unlimited sensitivity with detector size approaching the diffraction limit. Once an image is 'captured', cellular preprocessing of information allows extraction of high resolution information from the scene. Computer simulation of this system promises hyperacuity for machine vision.

Wilcox, Mike↗
NASA NTRS2007

Fiber-Optic Strain Gauge With High Resolution And Update Rate

An improved fiber-optic strain gauge is capable of measuring strains in the approximate range of 0 to 50 microstrains with a resolution of 0.1 microstrain. (To some extent, the resolution of the strain gauge can be tailored and may be extensible to 0.01 microstrain.) The total cost of the hardware components of this strain gauge is less than $100 at 2006 prices. In comparison with prior strain gauges capable of measurement of such low strains, this strain gauge is more accurate, more economical, and more robust, and it operates at a higher update rate. Strain gauges like this one are useful mainly for measuring small strains (including those associated with vibrations) in such structures as rocket test stands, buildings, oilrigs, bridges, and dams. The technology was inspired by the need to measure very small strains on structures supporting liquid oxygen tanks, as a way to measure accurately mass of liquid oxygen during rocket engine testing. This improved fiber-optic strain gauge was developed to overcome some of the deficiencies of both traditional foil strain gauges and prior fiber-optic strain gauges. Traditional foil strain gages do not have adequate signal-to-noise ratios at such small strains. Fiber-optic strain gauges have been shown to be potentially useful for measuring such small strains, but heretofore, the use of fiberoptic strain gauges has been inhibited, variously, by complexity, cost, or low update rate.

Figueroa, Fernando↗