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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 631 records · Page 35

Limex'87 ice surface characteristics and their effect upon C-band SAR sigantures

Ice surface characterization data were recorded during March 1987 in the Labrador Sea marginal ice zone, at the onset of spring melt. Measured data are used as input parameters in a simple scattering model to simulate the effects of temporal variations in material properties upon C-band scattering signatures. Snow moisture and surface roughness have a significant effect upon sigma(0)HH and large differences are predicted between undeformed floe surfaces and deformed or rubbled ice areas. The model reproduces a calibrated synthetic-aperture-radar (SAR)-derived signature obtained during the experiment with a reasonable degree of certainty. Predictions also simulate a trend observed in SAR images of increasing backscatter contrast between deformed and undeformed ice over period of surface warming.

Drinkwater, Mark R.↗

Low frequency propagation in the earth's magnetosphere

Using a model to simulate wave propagation, estimates were obtained on the effect of the earth's magnetosphere on the imaging potential of the Low-Frequency Space Array mission for observations above the ionosphere at frequencies below about 10 MHz. Results of this simulation show that, for imaging at 1.5 MHz, large orbital radii will be required. It is concluded that successful imaging from within the plasmasphere may depend upon the feasibility of correction schemes.

Dennison, Brian↗

Ultraviolet Galaxy Counts From STIS Observations of The Hubble Deep Fields

We present galaxy counts in the near and far ultraviolet (NUV and FUV) obtained from Space Telescope Imaging Spectrograph (STIS) observations of portions of the Hubble Deep Field North, (HDFN), the Hubble Deep Field South, (HDFS) and a parallel field near the HDFN. All three fields have deep (AB>29) optical imaging, and we determine magnitudes by taking the ultraviolet flux detected within the limiting optical isophote. An analysis of the UV-optical colors of detected objects, combined with a visual inspection of the UV images, indicates that there are no detectable objects in the UV images which are not also detected in the optical. We measure the detection area and completeness as a function of magnitude by taking the size-magnitude distribution of galaxies in the entire HDFN WFPC2 V+I image, applying the measured UV-optical colors from the detected galaxies, and determining the total area over which each galaxy would have been detected in the UV images. The average area for the simulated galaxies in each UV magnitude bin, (including galaxies which would not be detected at all), provides the effective area and completeness for the bin. We test this procedure with Monte Carlo simulations. The galaxy counts reach to AB=29 in both the NUV and FUV; 1 magnitude fainter than the HDF F30OW counts, and 7 magnitudes fainter than balloon-based counts. We compare our measured counts to various models.

Gardner, J. P.↗

Orion Nebula Movie

Footage shows the following simulations derived from Hubble Space Telescope images: (1) the tiling of the Orion mosaic; (2) Orion mosaic fly-through; and (3) a close-up of the Orion mosaic.

Source record↗

Modeling of the Multiparameter Inverse Task of Transient Thermography

Transient thermography employs preheated surface temperature variations caused by delaminations, cracks, voids, corroded regions, etc. Often, it is enough to detect these changes to declare a defect in a workpiece. It is also desirable to obtain additional information about the defect from the thermal response. The planar size, depth, and thermal resistance of the detected defects are the parameters of interest. In this paper a digital image processing technique is applied to simulated thermal responses in order to obtain the geometry of the inclusion-type defects in a flat panel. A three-dimensional finite difference model in Cartesian coordinates is used for the numerical simulations. Typical physical properties of polymer graphite composites are assumed. Using different informative parameters of the thermal response for depth estimation is discussed.

Plotnikov, Y. A.↗

Simulation studies of vestibular macular afferent-discharge patterns using a new, quasi-3-D finite volume method

A quasi-three-dimensional finite-volume numerical simulator was developed to study passive voltage spread in vestibular macular afferents. The method, borrowed from computational fluid dynamics, discretizes events transpiring in small volumes over time. The afferent simulated had three calyces with processes. The number of processes and synapses, and direction and timing of synapse activation, were varied. Simultaneous synapse activation resulted in shortest latency, while directional activation (proximal to distal and distal to proximal) yielded most regular discharges. Color-coded visualizations showed that the simulator discretized events and demonstrated that discharge produced a distal spread of voltage from the spike initiator into the ending. The simulations indicate that directional input, morphology, and timing of synapse activation can affect discharge properties, as must also distal spread of voltage from the spike initiator. The finite volume method has generality and can be applied to more complex neurons to explore discrete synaptic effects in four dimensions.

NASA Center ARC↗

Precision Formation Keeping at L2 Using the Autonomous Formation Flying Sensor

Recent advances in formation keeping for large numbers of spacecraft using the Autonomous Formation Flying are presented. This sensor, currently under development at JPL, has been identified as a key component in future formation flying spacecraft missions. The sensor provides accurate range and bearing measurements between pairs of spacecraft using GPS technology. Previous theoretical work by the authors has focused on developing a decentralized scheduling algorithm to control the tasking of such a sensor between the relative range and bearing measurements to each node in the formation. The resulting algorithm has been modified to include switching constraints in the sensor. This paper also presents a testbed for real time validation of a sixteen-node formation based on the Stellar Imager mission. Key aspects of the simulation include minimum fuel maneuvers based on free-body dynamics and a three body propagator for simulating the formation at L2.

McLoughlin, Terence H.↗

Avoiding Stair-Step Artifacts in Image Registration for GOES-R Navigation and Registration Assessment

In developing software for independent verification and validation (IVV) of the Image Navigation and Registration (INR) capability for the Geostationary Operational Environmental Satellite R Series (GOES-R) Advanced Baseline Imager (ABI), we have encountered an image registration artifact which limits the accuracy of image offset estimation at the subpixel scale using image correlation. Where the two images to be registered have the same pixel size, subpixel image registration preferentially selects registration values where the image pixel boundaries are close to lined up. Because of the shape of a curve plotting input displacement to estimated offset, we call this a stair-step artifact. When one image is at a higher resolution than the other, the stair-step artifact is minimized by correlating at the higher resolution. For validating ABI image navigation, GOES-R images are correlated with Landsat-based ground truth maps. To create the ground truth map, the Landsat image is first transformed to the perspective seen from the GOES-R satellite, and then is scaled to an appropriate pixel size. Minimizing processing time motivates choosing the map pixels to be the same size as the GOES-R pixels. At this pixel size image processing of the shift estimate is efficient, but the stair-step artifact is present. If the map pixel is very small, stair-step is not a problem, but image correlation is computation-intensive. This paper describes simulation-based selection of the scale for truth maps for registering GOES-R ABI images.

stair-step artifact↗

Avoiding Stair-Step Artifacts in Image Registration for GOES-R Navigation and Registration Assessment

In developing software for independent verification and validation (IVV) of the Image Navigation and Registration (INR) capability for the Geostationary Operational Environmental Satellite R Series (GOES-R) Advanced Baseline Imager (ABI), we have encountered an image registration artifact which limits the accuracy of image offset estimation at the subpixel scale using image correlation. Where the two images to be registered have the same pixel size, subpixel image registration preferentially selects registration values where the image pixel boundaries are close to lined up. Because of the shape of a curve plotting input displacement to estimated offset, we call this a stair-step artifact. When one image is at a higher resolution than the other, the stair-step artifact is minimized by correlating at the higher resolution. For validating ABI image navigation, GOES-R images are correlated with Landsat-based ground truth maps. To create the ground truth map, the Landsat image is first transformed to the perspective seen from the GOES-R satellite, and then is scaled to an appropriate pixel size. Minimizing processing time motivates choosing the map pixels to be the same size as the GOES-R pixels. At this pixel size image processing of the shift estimate is efficient, but the stair-step artifact is present. If the map pixel is very small, stair-step is not a problem, but image correlation is computation-intensive. This paper describes simulation-based selection of the scale for truth maps for registering GOES-R ABI images.

image registration↗

From Tomography to Material Properties of Thermal Protection Systems

The X-ray micro-tomography technique provides non-destructive characterizations of three-dimensional material micro-structures at spatial resolutions from the sub-micron to the centimeter scale. High quality micro-tomography images of NASA Thermal Protection System (TPS) materials are obtained using one of the brightest synchrotron X-ray sources available. Leveraging on NASA supercomputing capabilities, material properties and response are computed from tomography-data. This talk highlights the process and challenges of going from 3D images of actual material structures to simulations of properties and phenomena relevant to TPS material response, such as thermal conductivity, permeability, mass transport and high temperature reactions. The talk is addressed to a broad audience including scientists, engineers, researchers, educators, programmers, managers, and members of the media.

tomography↗

Developing Extended Reality Projects in Support of Design, Fabrication and Procedure

The goal of this internship was to improve and create virtual reality simulations and visualizations for use in parallel with the design, fabrication, and analysis of flight ready hardware for areas like the Environmental Control and Life Support Systems (ECLSS) and also Space Systems. Specifically, my work was done in the XRSpace lab at Marshall Space Flight Center (MSFC) with assistance directly and indirectly from workers at KSC, JSC and LaRC. Led by David Reynolds, the XRSpace lab develops products for various entities at NASA. The work done in the XRSpace lab focuses on Extended Reality (XR) solutions for both simulations and visualization capabilities. The goal of the lab is to support the larger systems of NASA and to help find ways that XR technologies can streamline and optimize the design process. Extended Reality is an umbrella term that encompasses Mixed Reality, Augmented Reality, and Virtual Reality. In this capacity, I was able to complete several elements in the design, building, testing, and deployment for a variety of immersive experiences, including a VR procedure simulation, visualization aids, and a 360-image capture tool.

Joseph Chambers↗

The View From Out Here: The Solar System Planets as Exoplanet Analogs

As we begin to characterize planets orbiting other stars, one of the most important tools available to us is the collection of disk-integrated solar system observations. To date, these have been limited in how they match up with expected exoplanet observations in terms of wavelength, time, viewing geometry, and separations. The Interstellar Probe mission could push the boundaries of planetary science by providing a much-needed and unique dataset for the solar system viewed as an extrasolar system in advance of the next generation of ground and space-based telescopes. Viewing the solar system at large separations over a long period serves several purposes. It acts as a practical test directly analogous to exoplanet observations under realistic conditions, including such effects as zodiacal dust (e.g., Roberge et al., 2012). Secondly, it allows for both the validation of forward models (that is, simulating a planet and generating spectra) and retrievals (where some of the planetary properties are not known) (e.g., Robinson et al., 2011; Agarwal and Wettlaufer, 2017). Third, the mission pro le would be able to collect data at both high- and low-phase angles, which are lacking for most of the solar system planets (e.g., Mallama and Hilton, 2018). Lastly, the long duration of the proposed mission would allow not only snapshots, but time resolved observations using the same instrument, highlighting the dynamic nature of the planets (e.g., seasonality, storms). The planets need not be resolved to make these observations, which eases instrumentation requirements. Here, we show simulations of what an Interstellar Probe imager would see, improving on work that was part of a white paper submitted to the Planetary Science and Astrobiology Decadal Survey. The opportunity for multiple full orbits for most of the solar system planets, including a full phase curve of Saturn, is unique and worth pursuing during the development of the Interstellar Probe mission.

Chester Harman↗

Experimental and Computational Analysis of a Rotating Detonation Combustor

Rotating detonation combustor (RDC) research has progressed along parallel experimental and computational paths with limited opportunities for validation. Validation is a crucial step to ensure RDC simulations provide an accurate representation of the physical phenomena, and thus, can be used with confidence for design optimization in different applications. In this study, data from a quasi-two-dimensional computational fluid dynamic simulation in an annular RDC are compared with experimental measurements including particle image velocimetry at 100 kHz. Results show good agreement between measured and simulated dynamic pressures, Chapman-Jouguet speeds, and static pressure distributions. Velocity measurements at the annulus exit show good temporal and quantitative agreement with simulations including spikes from the passing shock.

Detonation↗

Quantitative Phenotypic Analysis of Arabidopsis Thaliana Grown in Microgravity Using Soap, an Applied Artificial Intelligence

Phenotypic analysis is an essential step in studying the gravitropic responses and gravitational stress experienced by plants grown in microgravity. Many of the phenotypic traits analyzed in gravitropism studies, such as root length, leaf area, secondary root count, and number of root hairs, currently rely upon manual measurement methods for quantification. However, new advances in data analysis technology using artificial intelligence offer an opportunity for more efficient phenotypic analysis and a reduction of time spent in the data collection phase. In this project, the ability of a new artificially intelligent data collection software, SOAP (Simple Object Access Protocol), to collect and quantify phenotypic traits of Arabidopsis thaliana will be assessed. This project will test the measurements taken by an initial draft of the software. SOAP will take measurements of shoot length, a key phenotype used to assess A. thaliana stress response when grown in microgravity conditions. Shoot length measurements made by SOAP will be compared against a series of manual shoot length measurements. The comparison between the two methods of data measurement will provide valuable insight into the relative accuracy of SOAP and the margin of human error when conducting lab measurements.

Arabidopsis↗

Research and analysis of head-directed area-of-interest visual system concepts

An analysis and survey with conjecture supporting a preliminary data base design is presented. The data base is intended for use in a Computer Image Generator visual subsystem for a rotorcraft flight simulator that is used for rotorcraft systems development, not training. The approach taken was to attempt to identify the visual perception strategies used during terrain flight, survey environmental and image generation factors, and meld these into a preliminary data base design. This design is directed at Data Base developers, and hopefully will stimulate and aid their efforts to evolve such a Base that will support simulation of terrain flight operations.

Sinacori, J. B.↗

The NIRCam Optical Telescope Simulator (NOTES)

The Near Infra-Red Camera (NIRCam), the 0.6-5.0 micron imager and wavefront sensing instrument for the James Webb Space Telescope (JWST), will be used on orbit both as a science instrument, and to tune the alignment of the telescope. The NIRCam Optical Telescope Element Simulator (NOTES) will be used during ground testing to provide an external stimulus to verify wavefront error, imaging characteristics, and wavefront sensing performance of this crucial instrument. NOTES is being designed and built by NASA Goddard Space Flight Center with the help of Swales Aerospace and Orbital Sciences Corporation. It is a single-point imaging system that uses an elliptical mirror to form an U20 image of a point source. The point source will be fed via optical fibers from outside the vacuum chamber. A tip/tilt mirror is used to change the chief ray angle of the beam as it passes through the aperture stop and thus steer the image over NIRCam's field of view without moving the pupil or introducing field aberrations. Interchangeable aperture stop elements allow us to simulate perfect JWST wavefronts for wavefront error testing, or introduce transmissive phase plates to simulate a misaligned JWST segmented mirror for wavefront sensing verification. NOTES will be maintained at an operating temperature of 80K during testing using thermal switches, allowing it to operate within the same test chamber as the NIRCam instrument. We discuss NOTES' current design status and on-going development activities.

Kubalak, David↗

Automated Detection and Analysis of Resident Space Objects with the 1.3-Meter Eugene Stansbery-Meter Class Autonomous Telescope

Optical telescopes dedicated to the detection of orbital debris employ large-area detectors that generate a large number of images each night. Such surveys require automated data analysis pipelines that process the images and detect moving objects. We present an overview of the data analysis pipeline employed by the 1.3-meter Eugene Stansbery-Meter Class Autonomous Telescope (ES-MCAT) on Ascension Island, operated by NASA’s Orbital Debris Program Office. The pipeline enfolds the astrometric and photometric calibration of the images, star-trail removal, object detection, correlation over multiple sequential image frames, and orbital parameter estimation. The performance of the pipeline was investigated by means of Monte-Carlo simulations in which simulated object tracks were inserted into ES-MCAT images and then processed by the pipeline. This technique allows one to confidently estimate the completeness for the detection of resident space objects as a function of apparent magnitude and angular velocity. This paper discusses these techniques and provides examples using actual data.

Paul Hickson↗

Automated Detection and Analysis of Resident Space Objects with the 1.3-Meter Eugene Stansbery-Meter Class Autonomous Telescope

Optical telescopes dedicated to the detection of orbital debris employ large-area detectors that generate a large number of images each night. Such surveys require automated data analysis pipelines that process the images and detect moving objects. We present an overview of the data analysis pipeline employed by the 1.3-meter Eugene Stansbery-Meter Class Autonomous Telescope (ES-MCAT) on Ascension Island, operated by NASA’s Orbital Debris Program Office. The pipeline enfolds the astrometric and photometric calibration of the images, star-trail removal, object detection, correlation over multiple sequential image frames, and orbital parameter estimation. The performance of the pipeline was investigated by means of Monte-Carlo simulations in which simulated object tracks were inserted into ES-MCAT images and then processed by the pipeline. This technique allows one to confidently estimate the completeness for the detection of resident space objects as a function of apparent magnitude and angular velocity. This paper discusses these techniques and provides examples using actual data.

Paul Hickson↗