A document presents a summary of an onboard estimation algorithm now being used to calibrate the alignment of the Spitzer Space Telescope (formerly known as the Space Infrared Telescope Facility). The algorithm, denoted the S2P calibration filter, recursively generates estimates of the alignment angles between a telescope reference frame and a star-tracker reference frame. At several discrete times during the day, the filter accepts, as input, attitude estimates from the star tracker and observations taken by the Pointing Control Reference Sensor (a sensor in the field of view of the telescope). The output of the filter is a calibrated quaternion that represents the best current mean-square estimate of the alignment angles between the telescope and the star tracker. The S2P calibration filter incorporates a Kalman filter that tracks six states — two for each of three orthogonal coordinate axes. Although, in principle, one state per axis is sufficient, the use of two states per axis makes it possible to model both short- and long-term behaviors. Specifically, the filter properly models transient learning, characteristic times and bounds of thermomechanical drift, and long-term steady-state statistics, whether calibration measurements are taken frequently or infrequently. These properties ensure that the S2P filter performance is optimal over a broad range of flight conditions, and can be confidently run autonomously over several years of in-flight operation without human intervention.
This work was done by David Bayard of Caltech for NASA's Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Mechanics/Machinery category.
The software used in this innovation is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-43375.
This Brief includes a Technical Support Package (TSP).
Estimation Filter for Alignment of the Spitzer Space Telescope
(reference NPO-43375) 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 Estimation Filter for Alignment of the Spitzer Space Telescope, identified by NTR Number 43375. It is part of NASA Tech Briefs, which disseminate information about aerospace-related developments with potential broader technological, scientific, or commercial applications.
The primary focus of the document is on the Spitzer Autonomous Pointing Control Alignment Calibration Filter, which is crucial for the precise alignment and operation of the Spitzer Space Telescope. This innovation aims to enhance the telescope's ability to maintain accurate pointing during its observations, which is essential for capturing high-quality astronomical data.
The document outlines the technical aspects of the estimation filter, detailing its functionality and significance in the context of space exploration and astronomical research. It emphasizes the importance of such technologies in improving the performance of space instruments, thereby contributing to the success of missions that rely on precise measurements and observations.
Additionally, the Technical Support Package serves as a resource for those interested in the commercial applications of the technology developed under NASA's Commercial Technology Program. It provides contact information for further inquiries, specifically directing interested parties to the Innovative Technology Assets Management at JPL for additional assistance and information regarding research and technology in this area.
The document also includes a notice regarding the proprietary nature of the information contained within, indicating that it may be subject to export control regulations. It clarifies that the United States Government, nor any individual acting on its behalf, assumes liability for the use of the information provided, nor does it guarantee that such use will be free from privately owned rights.
In summary, this Technical Support Package highlights a significant technological advancement in the field of space exploration, specifically related to the Spitzer Space Telescope. It underscores the importance of precise alignment and calibration in astronomical observations and offers a pathway for further exploration and potential commercial applications of the technology developed.
