Variable Geometry Decelerator Planetary Entry Vehicles


Kawai Kwok
Sergio Pellegrino


The next generation of planetary entry vehicles is expected to deliver payloads that are much more massive than what have landed on planets in past missions. A notable example is the Mars Science Laboratory, which will carry a rover several times larger than the Mars Exploration Rover. For missions with such high landed mass, guided lifting entry in the hypersonic flight regime is critical to achieve precision landing and maneuverability of the entry vehicle becomes a necessary design feature.

In this joint collaborative study with Jet Propulsion Laboratory, we propose structural concepts that allow the entry vehicle to have variable aerodynamic characteristics through geometry changes. The variability of aerodynamic characteristics inherent in the vehicle geometry does not only favor maneuverability, but also allows a broader space for trajectory optimization. Traditional entry vehicles feature sphere-cone geometry that provides a favorable ballistic coefficient but a limited lift-to-drag ratio. An approximate aerodynamic study reveals that changing the cone angle is an effective way of altering aerodynamics of the vehicle. One proposed structural concept is to introduce corrugations of small amplitudes on the sphere-cone geometry. The corrugated surface then provides enough compliance to deform the vehicle to change the overall cone angle. Structural and trajectory simulation performed demonstrated that the variable geometry approach is a promising control technique.


  • Quadrelli, M.B., Boussalis, D., Davis, G., Kwok, K., and Pellegrino, S. (2009) Structural and control concepts for variable geometry planetary entry systems. 50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference. 4-7 May 2009, Palm Springs, CA, AIAA-2009-2100.