Determination of CHAMP Accelerometer Calibration Parameters

Abstract

One of the key science instruments for gravity science aboard CHAMP is a three-axis STAR accelerometer, which measures the non-gravitational accelerations acting on the spacecraft. These measurements are used in precise orbit determination and for gravity field estimation. Usually, the accelerometer output is not an absolute value of non-gravitational accelerations and has to be calibrated by applying a bias and a scale factor for each axis. Since the bias and scale factor parameters cannot be obtained from ground tests, they have to be determined using the flight data. This paper describes different approaches for determination of the CHAMP accelerometer calibration parameters: comparison of observed accelerations with accelerations computed using models, and determination of the parameters in orbit determination and gravity field recovery schemes. The impact of these calibration parameters on the gravity field recovery are also discussed.