Orbiter enthusiasts to develop an Orbiter add-on package called Mars for Less (MFL). I wrote about it quite a bit in 2006-2008 and even presented a paper (PDF) on it at the 2006 Mars Society Conference in Washington, DC. Fun stuff, especially since Andy McSorley and Mark Paton did most of the heavy lifting (and re-entering). I mostly did a lot of testing and writing (scenarios, blog posts, and the MSC paper). Mark has quite a knack for spacecraft design and especially for EDL (entry, descent, and landing in the trade). Since MFL is all about saving weight (well, it's also about medium-lift boosters, modular orbital construction, and living off the land on Mars), we wanted a very light heat shield. Mark decided to go with an inflatable one. He'd read some stuff about them, and since Orbiter isn't exactly rigorous about the structural integrity of spacecraft models anyway, he decided to give it a shot. It seemed to work within the aerodynamics of Orbiter. I entered the Mars atmosphere and safely landed dozens of times (mostly thanks to Mark's spiffy autopilot work).You can see a bunch of my Mars for Less screen shots on my Flickr site and a nice 7 minute video (not mine) of the MFL mission here.
and it worked. Of course this is a lot smaller than what we would need for our manned Mars lander, but hey, it's a start! Thanks to Colony Worlds for the tip and the photo.