Sulcata software simulates the operation of the Mars Science Laboratory (MSL) radar terminal descent sensor (TDS). The program models TDS radar antennas, RF hardware, and digital processing, as well as the physics of scattering from a coherent ground surface. This application is specific to this sensor and is flexible enough to handle end-to-end design validation. Sulcata is a high-fidelity simulation and is used for performance evaluation, anomaly resolution, and design validation.
Within the trajectory frame, almost all internal vectors are represented in whatever coordinate system is used to represent platform position. The trajectory frame must be planet-fixed. The platform body frame is specified relative to arbitrary reference points relative to the platform (spacecraft or test vehicle). Its rotation is a function of time from the trajectory coordinate system specified via dynamics input (file for open loop, callback for closed loop). Orientation of the frame relative to the body is arbitrary, but constant over time.
The TDS frame must have a constant rotation and translation from the platform body frame specified at run time. The DEM frame has an arbitrary, but time-constant, rotation and translation with respect to the simulation frame specified at run time. It has the same orientation as sigma0 frame, but is possibly translated. Surface sigma0 has the same arbitrary rotation and translation as DEM frame.
This work was done by Curtis W. Chen of Caltech for NASA’s Jet Propulsion Laboratory.
This software is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-46161.
This Brief includes a Technical Support Package (TSP).
Terminal Descent Sensor Simulation
(reference NPO-46161) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) concerning the Terminal Descent Sensor (TDS) Simulation, identified by the reference NPO-46161. It is part of NASA's Commercial Technology Program, aimed at disseminating aerospace-related developments with broader technological, scientific, or commercial applications.
The document outlines the simulation methodologies employed in the TDS, which is crucial for landing spacecraft on celestial bodies like Mars. It details the various frames of reference used in the simulation, including the simulation frame, DEM (Digital Elevation Model) frame, and spacecraft frames at different times. The internal handling of translations and rotations between these frames is managed by the software named Sulcata.
A significant focus of the document is on scene modeling and representation. It describes how local scenes are modeled for different combinations of antenna beams and parameters, allowing for overlapping scenes with varying speckle characteristics. The size of individual scattering cells in the simulation is adaptable, depending on factors such as range, velocity, and pulse width, with sizes ranging from approximately 100 meters to 1 centimeter.
The document also discusses the simulation options available, which include multiple methodologies for simulating I/Q (in-phase and quadrature) samples, time-domain synthesis of real samples, and analytical pulse shapes. These options allow for flexibility in simulating the behavior of the TDS under various conditions.
Additionally, the document emphasizes the importance of compliance with U.S. export regulations, as it may contain proprietary information. It provides contact information for further inquiries related to research and technology in this area, specifically through the Innovative Technology Assets Management at JPL.
Overall, the Technical Support Package serves as a comprehensive guide for understanding the TDS simulation, its methodologies, and its applications in aerospace technology, particularly in the context of planetary exploration and landing operations.
