Abstract:

For space objects in low Earth orbits, atmospheric density variations during geomagnetic disturbance could cause large orbit prediction error. An error correction method for short-term orbit prediction is proposed, which is based on the auroral hemispheric power data from POES. It can be found that the atmospheric density and orbit decrease are all correlated with hemispheric power. According to linear regression analysis, correction formulas for semi-major axis decrease and drag coefficients are proposed. Then the modified drag coefficients are used instead of its values in two-line elements (TLE) to predict the position by SGP4 model. As the atmospheric density variations caused by geomagnetic disturbance in extrapolation process are concerned in this method, influence of aerodynamic drag to the orbit is well reflected. This method is applied in the orbit prediction of the CHAMP satellite and the International Space Station in 2008 and the results show that the semi-major axis prediction error is reduced by about 50%, and the position prediction error is reduced by about 30%. Furthermore, the prediction error decreases of objects with different height in different years verify the validity and universality of this method.

Key words: Orbit prediction, Geomagnetic disturbance, Atmospheric density, Linear regression