Larry J said:

>Direct aerocapture at Mars may be too big a step, at least until some
>experience is gained. It might be better to briefly enter the atmosphere
>at a shallow angle to burn off some excess velocity then use rocket
>engines to get rid of the rest for orbital insertion. Every bit of velocity
>burned off in the atmosphere pays big dividends in reduced propellant
>needed to enter orbit.

Actually we need a flight test experiment to demonstrate aerocapture to Mars. There was a proposal to do this called "Demon" but it never got past the early proposal phase. The flight test experiment would involve a biconic geometry that was a scale model of a manned vehicle. The vehicle would come into the martian atmosphere fast and deep in order to get the Reynolds Number and shocklayer CN emission right. The model would then go through a wild set of maneuvers to validate the different control laws and eventually fly out of the atmosphere to some predetermined orbit. It would be a pure engineering science mission with the heat shield wired to the gills with sensors. Getting something like this funded is almost impossible because there is no actual Mars science attached to it. The last flight test experiments were done under the Apollo program (Project Fire Flight). We still use Fire's data for CFD validation.

Gary