A study of the navigation for a spacecraft by using Modified Orbit estimator

The error budget analysis is presented which quantifies the effects of different error sources in the Earth-based orbit determination process when the orbit estimation filter is used to reduce radio metric data. The estimator strategy differs from more traditional filtering methods in the nearly all of the principal ground system calibration errors affecting the data are represented as filter parameters. Error budget computations were performed for a Venus mission interplanetary cruise scenario for cases in which only X-band Doppler data were used to determine the spacecraft´s orbit, X-band ranging data were used exclusively, and combined set in which the ranging data were used in addition to the Doppler data. Random nongravitational accelerations were found to the largest source of error contributing to the individual error budgets