For a given inertial frame of reference, the software combines the spacecraft orbits with the spacecraft attitude quaternions, and rotates the body-fixed reference frame of a particular spacecraft to the inertial reference frame. The conversion assumes that the two spacecraft are aligned with respect to the mutual line of sight, with a parameterized time tag. The software is implemented in Python and is completely open source. It is very versatile, and may be applied under various circumstances and for other related purposes. Based on the solid linear algebra analysis, it has an extra option for compensating the linear pitch.
This software has been designed for simulation of the calibration maneuvers performed by the two spacecraft comprising the GRAIL mission to the Moon, but has potential use for other applications. In simulations of formation flights, one needs to coordinate the spacecraft orbits represented in an appropriate inertial reference frame and the spacecraft attitudes. The latter are usually given as the time series of quaternions rotating the body-fixed reference frame of a particular spacecraft to the inertial reference frame. It is often desirable to simulate the same maneuver for different segments of the orbit. It is also useful to study various maneuvers that could be performed at the same orbit segment. These two lines of study are more time- and labor-efficient if the attitude and orbit data are generated independently, so that the part of the data that has not been changed can be “recycled” in the course of multiple simulations.
This work was done by Dmitry V. Strekalov, Gerhard L. Kruizinga, Meegyeong Paik, Dah-Ning Yuan, and Sami W. Asmar of Caltech for NASA’s Jet Propulsion Laboratory.
This software is available for commercial licensing. Please contact Daniel Broderick of the California Institute of Technology at
This Brief includes a Technical Support Package (TSP).
Description and User Instructions for the Quaternion_to_orbit_v3 Software
(reference NPO-47701) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package for the "Quaternion_to_orbit_v3" software developed by NASA's Jet Propulsion Laboratory (JPL). It serves as a guide for users interested in simulating calibration maneuvers performed by the GRAIL (Gravity Recovery and Interior Laboratory) mission, which involved two spacecraft orbiting the Moon. The software is designed to coordinate spacecraft orbits with their attitudes, represented as quaternions, which are mathematical constructs used to describe rotations in three-dimensional space.
The primary function of the software is to combine given orbital data with quaternion data that may originate from different orbits. This capability allows users to simulate the same maneuver across various segments of an orbit, facilitating the study of different maneuvers that could be executed in the same orbital segment. The document outlines the structure of the quaternion files, which include time and quaternion components, and describes how the software generates output files that represent the results of the simulations.
Key features of the software include the ability to specify which spacecraft is performing a maneuver, the index of the quaternion file corresponding to the nominal line of sight, and the option to correct for pitch due to orbital motion. The output includes quaternion files formatted for further analysis and graphical representations of yaw and pitch angles over time.
The document also emphasizes the importance of simulating spacecraft maneuvers efficiently, allowing for the recycling of unchanged data across multiple simulations. This approach is particularly beneficial in formation flight scenarios, where precise coordination between spacecraft is crucial.
In addition to its specific application to the GRAIL mission, the software has broader implications for other aerospace applications, making it a valuable tool for researchers and engineers in the field. The document concludes with contact information for further assistance and a disclaimer regarding the use of the information provided.
Overall, the Technical Support Package serves as a comprehensive resource for users of the Quaternion_to_orbit_v3 software, detailing its functionalities, applications, and the underlying principles of quaternion mathematics in spacecraft navigation and maneuver simulation.
