Modeling Reaction Control System Effects on Mars Odyssey

During the Mars 2001 Odyssey aerobraking mission, NASA Langley Research Center performed six-degree-offreedom simulations to model rotational motion of the spacecraft. The main objective of this study was to assess the reaction-control-system models and their effects on the atmospheric flight of Odyssey. Based on these models, a comparison was made between data derived from flight measurements to simulated rotational motion of the spacecraft during aerobraking at Mars. The differences between the simulation and flight-derived Odyssey data were then used to adjust the model aerodynamic parameters as a result of reaction-control-system firings to achieve a better correlation. Nomenclature A = reference area, m 2 ay = acceleration in y body coordinate frame, m/s 2 C D = drag coefficient Cm = moment coefficient L = reference length, m MCM = moment about the center of mass m = spacecraft mass, kg q = dynamic pressure, N/m 2 ρ = atmospheric density, kg/m 3