Combined Space-Ground Autonomy for the BIRD Small Satellite Mission

Abstract

As part of the BIRD satellite mission, a GPS-based onboard naviagtion system (ONS) has been developed which supports the attitude control system, the geocoding of öayload data as well the onboard time synchronization. In addition on the ONS functions, the GPS position data are applied to estimate the mean orbital elements and the ballistic coefficient of the SGP4 analytical orbit model using a Kalman filter. Based on the estimated mean elements, onboard eclipse predictions and station contact forecasts are performed and NORAD-compatible Twoline elements are generated. A combined space-ground autonomy is achieved, since the Twoline elements are transmitted from the BIRD satellite to an experimental ground statio and thus allow an autonomous operation of the station without the need for a dedicated ground-based orbit interface.