Tech Briefs

Ionospheric Slant TEC Analysis Using GNSS-Based Estimation (IonoSTAGE)

At the time of this reporting, IonoSTAGE has been operated successfully under both UNIX and Macintosh operating systems. NASA’s Jet Propulsion Laboratory, Pasadena, California As signals emitted by global navigation satellite systems (GNSS) propagate toward users on or near the surface of the Earth, they experience delay due to the presence of charged particles in the ionosphere. Currently, ionospheric delay is the largest source of GNSS positioning error. To guarantee the safety of airline navigation based upon GNSS signals, satellite-based augmentation systems have been developed to ensure the accuracy, integrity, availability, and continuity of user position estimates derived from GNSS measurements.

Posted in: Information Sciences, Electronics & Computers, Briefs, TSP

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Preparation, Planning, and Concept Demo of a Technique to Find ≈7-to-10-m Near Earth Asteroids

A paper describes a new technique designed to increase significantly the sensitivity for finding and tracking small, dim, and fast-moving near Earth asteroids (NEAs). The technique relies on a combined use of a novel data processing approach and a new generation of high-speed CCD cameras. These new cameras have very low readout noise (≈le–) and allow taking short exposures of moving objects at high frame rates, effectively “freezing” their motion on the CCD. A long-exposure image is synthetically created as if the telescope were tracking the object with a significantly higher SNR — an approach called “synthetic tracking.” By changing the shift/add vector, multiple dim objects moving in different directions can be detected in the same data set.

Posted in: Physical Sciences, Briefs

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Implementation of a Terrain Radiometric Correction for UAVSAR

A paper discusses a calibration method suited to correct variations of UAVSAR (unmanned aerial vehicle synthetic aperture radar) backscatter with topography. To use radar backscatter to estimate forest biomass on terrain with slopes, it is necessary to remove the effect of topography. The remaining signal should be related to biomass. The hybrid approach uses the radar line of sight to project an oversampled version of the Digital Elevation Model into radar coordinates for summation. Terrain topography has a major impact on the radar backscatter. Slopes facing the radar appear very bright while slopes facing away appear darker.

Posted in: Information Sciences, Electronics & Computers, Briefs

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Picoradian Staring Astrometry Using a Simple Staring Telescope

A document describes solutions to problems of astrometry at the microarc-second (picoradian) level using a simple staring telescope. The problems include field-dependent beam-walk on the telescope’s mirrors, pixel position irregularity and distortion over time, non-flat intra-pixel quantum efficiency, and systematic errors inherent in the most common image centroiding algorithms (imperfect knowledge of the point spread function).

Posted in: Information Sciences, Electronics & Computers, Briefs

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Missing Value Imputation in Astronomical Time-Series Data

A document describes a solution to missing flux values in time-domain optical and radio astronomical survey data that form “light curves.” The technique incorporates a priori astronomical knowledge into a missing value imputation technique. It is assumed that missing values in astronomical time series are either Missing At Random (MAR), or missing due to the flux of the source falling below the instrument’s sensitivity threshold, termed Threshold Removed Observations (TRO).

Posted in: Information Sciences, Electronics & Computers, Briefs, TSP

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Testing Astronaut-Controlled Surface Robots from the International Space Station

NASA and the European Space Agency (ESA) are currently developing robots that can be remotely operated on planetary surfaces by astronauts in orbiting spacecraft. The primary objective of this work is to test and demonstrate crew-controlled communications, operations, and telerobotic technologies that are needed for future deep space human exploration missions.

Posted in: Electronics & Computers, White Papers, Briefs

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Step on It! Walking for Power

What would be an alternative energy resource that could work well in the middle of a crowded city? The answer was a technology that harvests mechanical energy of walking feet and converts it to electrical energy via a special floor tile. But it was a big step from theory to practical design.

Posted in: Electronics & Computers, White Papers, Briefs

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