Refinement of Parameters and Motion Forecast for High-Orbit Objects with a Big Area to Mass Ratio

The purpose of this report is to develop the methods and algorithms for determination of orbits of objects with a big area to mass ratio. Objects with a big area to mass ratio (AMR>1 m/kg) are usually located on high Earth orbits. Their orbits greatly evolve under the influence of solar radiation. The disturbing influence of solar radiation considerably exceeds disturbances caused by the eccentricity of the Earth gravity field and the influence of the Moon and Sun gravitation. Because of the lack of knowledge on the orientation and form of objects, the acceleration produced by the solar radiation pressure changes greatly in its value and direction. This makes it impossible to determine the orbit for long intervals of time and results in a considerable increase of the forecasting errors. A necessity arises to include in the number of the refined parameters the vector characterizing the solar radiation value and the direction of its pressure, along with the object state vector. An approach is considered for the determination of the orbits and motion forecasting of objects with a big AMR. A limited span of the measurement interval in some cases is insufficient for the determination of a necessary set of parameters. The direction of the vector of acceleration caused by the solar radiation pressure can vary considerably, but in a limited range, deviate from the direction Sun-object. An algorithm is proposed for a joint determination of the object orbital parameters and the vector of additional acceleration, caused by the solar radiation pressure with an account of a priori information. An algorithm is described for formation of a weight matrix of a priori vector taking into account the range of its variation in value and direction. The questions are discussed of matching newly generated orbits of objects with a big AMR to the orbital catalog. A matching algorithm is proposed taking into account the errors in determination of objects’ state vectors and the density of occupation of a considered part of orbital parameters space with other objects. An example is given of determination and forecasting of a real SO orbit and estimation of error forecasting on the basis of real measurements obtained by ground facilities.