Mass Polar Lander aerothermodynamic and entry dispersion analysis

An analysis of the aerothermodynamics and trajectory dispersions experience d by the Mars Polar Lander entry system was performed and is documented her ein. Because the Mars Polar Lander aeroshell (forebody) is based on the Mar s Pathfinder aeroshell, the Pathfinder aerodynamic database was used by Loc kheed Martin Astronautics for their trajectory analyses. However, the after bodies of the two vehicles are different. The effects of the different geom etry and different trajectory were isolated, and the Pathfinder aerodynamic database was found to be appropriate for the Mars Polar Lander entry work with minor modifications. Independent heating calculations were conducted, which agree with the heating analyses done at Lockheed Martin Astronautics. Also, it was determined that, at the expected parachute-deploy conditions, the area of recirculated how extends less than two body lengths behind the vehicle. The extent of this recirculation region can impact successful par achute deployment. A six-degree-of-freedom simulation of the entry phase wa s developed, including much of the actual flight code for the attitude cont rol autopilot. This simulation was exercised to evaluate the autopilot and overall system performance during entry and to evaluate response to dispers ions that might affect the entry trajectory. It was determined that the aut opilot keeps the vehicle oriented correctly for the disturbances modeled. A lso, the six-degree-af-freedom simulation was used in a Monte Carlo analysi s to determine the expected footprint and altitude at parachute deploy.