Kinematic Orbit Determination for Low Earth Orbiters (LEOs)

Abstract

Kinematic point positioning of a Low Earth Orbiter (LEO) using GPS data is one possibility to get precise orbit information. This approach is followed at the Astronomical Institute of the University of Bern (AIUB) as an alternative to the dynamical orbit determination. Kinematic point positioning allows to recover the trajectory of the LEO without making use of any a priori gravity field information. This may be very useful for gravity field recovery, in particular in view of present and upcoming satellite missions like CHAMP, GRACE and GOCE which all have an accelerometer on board. The emphasis of this paper is to study the effect of different data screening options on the quality of the kinematic orbit for a LEO. The impact of observations at low elevations in conjunction with elevation-dependent weighting is investigated. The tests are carried out using data from SAC-C and CHAMP. Comparison with dynamic orbits of the satellites indicate that a kinematic LEO orbit at the decimeter accuracy level is feasible provided good code and phase GPS data is available.