(Georgia Institute of Technology, 2010-05-05)
Dutta, Soumyo
Flight data from an entry, descent, and landing (EDL) sequence can be used to reconstruct the vehicle’s trajectory
as well as compute the associated uncertainty. The atmospheric profile encountered by the vehicle can
similarly be estimated from the flight data. Past Mars missions have contained instruments, such as accelerometers,
gyroscopes, and radar altimeters that do not provide direct measurement of the free-stream atmospheric
conditions. Thus, uncertainties in the atmospheric reconstruction and the aerodynamic database knowledge
cannot be separated. However, the upcoming Mars Science Laboratory (MSL) will take measurements of the
pressure on the aeroshell forebody during entry. These measurements will provide means to determine the
free-stream conditions and to separate the atmospheric and aerodynamic uncertainties. In this paper, analytical
methods to statistically estimate trajectories and free-stream conditions from flight data and to quantify
uncertainties in these parameters are discussed. A sample data set from a ballistic range test of an Orion Crew
Exploration Vehicle (CEV) model is then used to demonstrate results from applying these procedures. This
approach utilizes the same techniques and toolset planned for subsequent application for the reconstruction of
MSL’s EDL sequence in 2012.