Look at the drawing. The Ares 5 is nowhere near an order of magnitude larger and it is intended to send humans to both the Moon and Mars. It is sufficient to send humans to Mars based on NASA's draft Mars plans which are based on Zubrin's plans contrary to those who pretend Zubrin is a nutjob with no influence. Order of magnitude larger vehicles are only needed if you take the pre-Zubrin approach of hauling your return fuel to Mars. Zubrin pointed out a better way and NASA has adopted it.

You didn't answer the simple direct question - Do you agree the Jupiter plan does not bother to meet the requirement to be useful for Manned Mars Missions? I know for a fact Griffen and Horowitz designed the Ares 5 to meet that criterion as I've heard it directly from them. It's OK to answer you don't know, but it sounds like you might agree and I really want to know what others read between the lines. I'm not sure either, but the big silence on the issue and the downsizing really smells to me like an apples to oranges swap not a more efficient way to meet the same objectives.

One big difference between NASA and Zubrin is a 6 man crew versus a 4 man crew. I disagree that you have to have a Doctor and a Biologist. Why send a Doctor who is going to be idle most of the time? Send a research doctor who is trained in medicine, but who's primary function is crew biologist and has the requisite experience to to handle potentially dangerous microorganisms (even if it's not likely to be an issue precautions are warranted due simply to dealing with an unknown). I don't remember which other of Zubrin's dual function crewman NASA split in two.

I also think it is a very bad idea to leave your return vehicle unmanned in space for two years. NASA does this so they can have a roomy return vehicle, but I think the risk of mechanical failure outweighs the risk of crew issues in more cramped quarters. Send some good VR equipment and people who don't need a lot of personal space. Zubrin's plan may be cramped, but are not beyond reason or human experience.

Those are the big differences between NASA and Zubrin's plans and it should be obvious the divergence is caused by reasonable differences of opinion on both sides not that the idea of in-situ resource utilization and a long term science mission (far beyond flags and footprints) has been ignored.

Regards,
Mark