This project involves calibrating accelerometer data from the aero-braking phase of the Mars Reconnaissance Orbiter.  Density estimates of the Martian atmosphere are desired which are directly calculated from accelerations caused by atmospheric drag.  Accelerations caused by non-atmospheric forces must be modeled and corrected.  Corrections for sensor bias, center of mass offset, and fuel slosh are sought.  These calibrations will allow refinement of the data used for estimating density and zonal winds during aero-breaking operations, maximizing the scientific value of the data posted in the Planetary Data System.