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Simulating Images of a Rising or Setting Sun

NASA’s Jet Propulsion Laboratory, Pasadena, California This software simulates Sun images observed on the ground and from space with an easy-to-use analytical approach and with high accuracy. It is a simple, analytical approach with the accuracy of a rigorous, multilayer model. The existing analytical approach cannot predict when the image of the Sun is blocked by the surface of the Earth, but the current approach can.

Posted in: Briefs, Electronics & Computers

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Partition Level Application Test for Orion (PLATO)

Lyndon B. Johnson Space Center, Houston, Texas For Orion Exploration Flight Test One (EFT-1), the unit-under-test for flight software verification has been chosen as the entire integrated flight software load. At the time of this reporting, the unit test tool, while powerful, operates on very small units, usually classes. This leaves a sizable gap between unit testing and verification. Orion flight software is divided into ARINC 653 partitions, and partition level testing is in this large gap.

Posted in: Briefs, Electronics & Computers

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Computer Modeling for Generation of Synthetic Radio Reflection-Transmission Tomography (RRTT) Data

Goddard Space Flight Center, Greenbelt, Maryland Numerical algorithms capable of generating synthetic radio tomography data (reflection transmission data) for asteroids, comets, and other near-Earth orbits (NEOs) were developed. Future missions to main asteroid belt objects, NEOs, and other small bodies of the solar system will aim to investigate the surface and subsurface compositions and internal structure of these objects with help of an onboard, low-frequency radio sounder. The resulting numerical model thus developed will be useful in performing trade studies required for designing an optimum radio sounder for the future missions. The forward numerical model will also be important for estimating structural properties of the small objects from the data collected by these future missions.

Posted in: Briefs, TSP, Electronics & Computers

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Designing Planning Information for Automation into PRL

Lyndon B. Johnson Space Center, Houston, Texas Automation and autonomy are key elements in realizing the vision for space exploration. The NASA Exploration Technology Development Program (ETDP) has been developing several core autonomy capabilities, one of which is called a procedure representation language (PRL). PRL can be automatically translated into code that can be executed by NASA-developed autonomous executives.

Posted in: Briefs, TSP, Electronics & Computers

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The OCO-2 Level 2 Retrieval Algorithm

Algorithm derives estimates of the column averaged atmospheric CO2. NASA’s Jet Propulsion Laboratory, Pasadena, California The Orbiting Carbon Observatory (OCO) strives for trace gas observations with unprecedented accuracy and precision. This requires a retrieval algorithm with many major improvements over existing retrieval software in the representation of the transfer of solar radiation through the atmosphere and instrument, such as full multiple-scattering calculation for each iteration step and correction for effects of polarization. In addition, the software allows retrieval of space-based and ground-based observations, so that potential algorithmic biases can be minimized for validation experiments. Furthermore, due to the flexible architecture of the software, spectra of existing similar instruments can be analyzed, which facilitates early testing using real space-based observations.

Posted in: Briefs, TSP, Electronics & Computers

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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: Briefs, TSP, Electronics & Computers

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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: Briefs, TSP, Electronics & Computers

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