Entry, Descent and Landing "System" Performance Analysis Tool with Results for Mars

With the renewed interest in crewed missions to Mars, there is a need for s ystem-level analysis of the Entry, Descent and Landing (EDL) vehicles needed for these missions which will require an increase of at least an order of magnitude in the landed mass performance compared to previous successful robotic missions and ones curren tly planned for the near future. To support research in this area in the author’s research group, a planetary EDL simulation and sensitivity analysis tool has been created which allows for the variation of a number of relevant parameters and provides the user with performance data. This facilitates analysis of the effect of individual vehicle and mission design parameters on the overall EDL system landed mass performance. The tool assumes an EDL system that uses a combination of an appropriately shaped heatshield and rocket engines for deceleration since these technologies are considered extensible to large missions. The tool is based on equations of motion in a rotating reference frame with origin at the center of the planet. Aerodynamic entry is simulated based on userspecified aerodynamic characteristics. The user also specifies criteria for transition from aerodynamic entry to propulsive descent and provides performance data but not the size of the rocket engine. The propulsive descent part of the traje ctory simulation contains an internal optimization scheme to size the descent propulsion system. To date, the tool has been validated with experimental data fr om the Mars Pathfinder mission as well as simulated data. The current tool uses an atmospheric m odel of Mars based on Pathfinder data. However, the tool is designed to be able to simulate EDL for any planetary body with appropriate specification of planetary constants and a planetary atmospheric model. Also provided is a visualization routine for eas y visualization of the effects of individual design parameters on the overall EDL system performance. This paper describes the various components of the tool and presents some results to illustrate the functionality of the tool.