Estimation of non-gravitational acceleration difference between two co-orbiting satellites using single accelerometer data

Non-gravitational accelerations acting on two closely co-orbiting satellites are highly correlated, and one satellite’s non-gravitational accelerations, sensing by accelerometer, can be transferred for the other satellite. NASA/DLR GRACE mission has been suffering from intermittent single accelerometer situations due to power limitation beyond its design life time. To overcome this situation, three estimation methods to predict one satellite’s non-gravitational acceleration using a weighted moving average of another satellite’s data are proposed Differential non-gravitational acceleration projection along velocity direction is used to evaluate the three methods with the GRACE flight data. If no bias adjustment is performed during preprocessing, one of the new methods shows an accuracy improvement over the time-shift method, which utilizes a single epoch data from the other satellite. With a bias adjustment, the time-shift method is preferred for its simplicity. The annual variations of the differential acceleration projection and estimation errors are analyzed using long-term GRACE flight data. The differential acceleration magnitude is closely related to solar activity, and therefore large estimation errors occur in the geomagnetic equator around noon, local time.