Back in the early 1990s, I read of a proposal to increase the decay rate of spent rocket bodies. The proposal was to inflate a large Echo-type balloon attacked to the rocket body to increase both the drag coefficient and the surface area. The analysis showed a dramatic reduction in the time it took for a rocket body's orbit to decay, in some cases from a matter of months to a few days. I don't know if anyone has actually attempted this, but the basic concept seems sound.

I'd love to see some tests of the aerocapture idea. It sounds great in theory but, to my knowledge, no one has actually tried it yet. We know aerobraking works. If we can conduct a pile driver test to replicate the 13km/sec Mars return velocity to aerocapture, followed by relatively fast aerobraking to lower the apogee (that's where the ballute comes in), then we might have a good combination for manned flights. Like the rocket body proposal, the ballute would be intended to increase surface area and drag coefficient to speed the aerobraking process, not to handle the entire reentry.

My goal is to safely put the returning vehicle into orbit around the Earth, perhaps for refit and reuse on another mission. That may not be practical or worthwhile on a very long mission, but potential reuse seems a worthwhile goal. If not, then use aerocapture for the initial Mars return, followed by a conventional reentry to the surface. Aerocapture might be combined with a certain amount of thruster induced delta-v to lower the apogee, followed by a deorbit burn at apogee for the reentry.

All I'm suggesting is that a direct reentry from Mars might put too many constraints on the CEV design and mission profile. Perhaps a two-step process would be better.