Barycentric Ephemeris
Final Report Abstract
In project 1 (PN1) of the research unit FOR1503 we lay the foundation for a new solar-system barycentric ephemeris. Our main focus was on the development of a competitive mathematical framework for the dynamical model of the translational motions. Rather than starting from scratch, we rebuilt an existing LLR analysis software package in order to solve the more general task of ephemeris construction for all major bodies as well as for a set of hundreds of major main belt asteroids. We proved the significance of an extensive treatment of minor bodies and of higher order figure-figure effects for selected major bodies. As a result, we raised the maximum degree and order of the built-in gravitational field models for the Earth and for the Moon. Furthermore, we implemented a mass ring for the vast number of remaining asteroids, and also for trans-Neptunian objects. We did not include individual TNOs in our numerical integration. We introduced a novel approach for model parameter estimation, namely the use of a stochastic method instead of a gradient method like least squares adjustment. An evolution strategy with covariance matrix adaptation was used to perform force model optimizations. First tests on its applicability were the retrieval of optimal MBA mass ring parameters in a simplified simulation scenario. Another test was performed on the determination of gravitational parameters for a few individual minor bodies. This time we used more realistic noisy observations. The same evolution strategy was used to retrieve the GM values in good agreement with the reference values which were taken from the DE430 ephemeris. We exploited the use of parallel programming techniques based on OpenMP, becaause it is perfectly suited for the evolution strategy approach. To access our ephemeris for later use via a de-facto standard method, we implemented an interface to the SPICE toolkit. Our development of a non-classical ephemeris construction approach made IFE’s LLR analysis software more competitive and flexible for additional research activities.
Publications
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(2014): Lunar Laser Ranging and Relativity, in: Frontiers in Relativistic Celestial Mechanics – Volume 2: Applications and Experiments, ed. S. Kopeikin, De Gruyter, p. 103-156
Müller, J., Biskupek, L., Hofmann, F., Mai, E.
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(2018): Application of an Evolution Strategy in Planetary Ephemeris Modeling, Advances in Space Research
Mai, E., Müller, J., Oberst, J.
