Note, for all you "SpaceX and NASA are competitors" people, that the Red Dragon design study was something that NASA paid for.[1] SpaceX and NASA are are on the same side in reality. Only in magical internet flamewarland, carried out by people who don't do any of this for a living, are they in opposition.
[1]: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2012001...