12/10/2011: Mars Entry Aerodynamics by Prof. Hans Hornung
Two Phenomena of Mars Entry Aerodynamics
October 12, 2011, 16:15-17:00, ML H 44, ETH Zurich
Prof. Hans G. Hornung
Emeritus Director of GALCIT, Caltech, Pasadena, USA
The vibrational excitation and dissociation of carbon dioxide behind the bow shock of a spacecraft entering the Martian atmosphere absorb so much energy that the density ratio across the shock can reach very high values (up to 18). One of the consequences is that the vorticity produced by the curved shock is very large and forms a shear layer that becomes unstable, as will be shown by computational and physical experiments. Another feature of the high density ratio is that on the spherically blunted cone shape that will be used for the Mars Science Laboratory, the sonic line can jump from the trailing edge of the cone to the spherical part. This can bring about a pitch instability of the capsule. For this and other reasons an ellipsoidal shape is much more desirable, as will be shown by computational experiments.