摘要 :
Generic algorithms have gained popularity as an effective procedure for obtaining solutions to traditionally difficult space mission optimization problems. In this paper, a brief survey of the use of genetic algorithms to solve ...
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Generic algorithms have gained popularity as an effective procedure for obtaining solutions to traditionally difficult space mission optimization problems. In this paper, a brief survey of the use of genetic algorithms to solve astrodynamics problems is presented and is followed by new results obtained from applying a Pareto genetic algorithm to the optimization of low-thrust interplanetary spacecraft missions.
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The stability parameter Q behavior in disk galaxies is discussed. The influence of various factors on its radial variations is considered. A range of possible values of Q as a consequence of dynamical properties connected with the...
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The stability parameter Q behavior in disk galaxies is discussed. The influence of various factors on its radial variations is considered. A range of possible values of Q as a consequence of dynamical properties connected with the morphology of these galaxies is suggested. Applications for NGC 891, NGC 4244, and NGC 5907 are proposed.
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In the field of astrodynamics the numerical values of various physical constants are required with the greatest precision possible. This document explains that generally the most desirable units for astrodynamical work are differe...
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In the field of astrodynamics the numerical values of various physical constants are required with the greatest precision possible. This document explains that generally the most desirable units for astrodynamical work are different from those used in the laboratory and rely heavily on astronomical observatlons. Furthermore, there is much interdependency among them complicated by accidental and unkown systematic errorB. By employing statistical methods the accidental errors are reduced and the use of metastatisties reduces the effects of the unknown systematic errors. These techniques are applied to presently available data to establish the best values of various gravitational, geodetic and related constants. The report also recognizes the fact that none of the constants are definitive, but subject to further improvement in the future.
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The ability to successfully perform many aspects of a satellite mission is directly impacted by the ability to precisely determine and predict the satellite's orbit through high precision orbit determination. The orbit determinati...
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The ability to successfully perform many aspects of a satellite mission is directly impacted by the ability to precisely determine and predict the satellite's orbit through high precision orbit determination. The orbit determination process relies on numerical procedures, satellite measurements, and force modeling to generate the orbit solution and prediction. As a foundation for detailed force modeling, gravity forces due to the distribution of the Earth's mass must be accurately modeled. In prior research, a number of geopotential models and ocean tide models have been developed for use in orbit determination. This paper examines current and historically recommended geopotential and ocean tide models using the Naval Research Laboratory's Orbit Covariance Estimation and ANalysis tool. Geodetic satellites with high precision satellite laser ranging measurements are used as test cases to evaluate the solution accuracy and predictive capabilities of the geopotential and ocean tide models. Orbit fit and prediction comparison metrics are generated for multiple geopotential and ocean tide model combinations. Results show that use of the EGM2008 geopotential model combined with the GOT4.8 ocean tide model generally results in predictive orbit solutions that more closely follow the definitive orbit solution. However, these results vary for different satellite orbits and time past the initial fit span.
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