Mars Sample Return Direct Earth Approach Navigation Analysis

This paper describes the navigation analysis, results and filter strategies planned by the European Space Agency (ESA) and the National Aeronautical and Space Administration (NASA) navigation Teams for the joint ESA and NASA Mars Sample Return (MSR) mission, targeting a direct approach to the Earth landing site at the Utah Test and Training Range (UTTR). Direct approach strategy and navigation filter assumptions will be discussed for ESA’s Earth Return Orbiter (ERO) in order to satisfy approach navigation requirements and to achieve the desired landing footprint uncertainty at the UTTR landing site for the Earth Entry System (EES). After the EES is released three days prior to atmospheric entry, alternate tracking measurements are needed since the EES cannot be tracked after release by ESA's European Space Tracking network (ESTRACK) and NASA's Deep Space Network (DSN). A navigation sensitivity analysis to the alternate tracking measurement accuracy will be presented.