NEO Mission
Should the new hardware being developed for the Moon-Mars-Beyond program be put to use for a NEO rendezvous mission, before a Mars mission is attempted? The scientific return from such a mission would be hugely valuable, while it would also serve as a testbed for the technology and methodology used on a Mars expedition.
WRT Mars? Not sure it matters.
NEO rendezvous sounds really interesting, and I think it would be totally worthwhile for the scientific return, as you suggested...
but I'm not sure it would help a Mars expedition, because (to my semi-knowledge =) ) the requirements for a NEO rendezvous would probably be pretty different from a Mars mission. I can imagine a NEO having far less gravity than Mars (a NEO "landing" would be more like a "docking") and having totally different delta-V requirements, therefore very different hardware.
A far-out enough NEO might require a radiation-shielding habitat module with enough resources for a lengthy flight, but that might be as about as common as it gets with a Mars mission.
A NEO mission would be pretty interesting, but I'm not sure it would necessarily matter whether it happened before or after a Mars mission.
From my understanding, it
From my understanding, it can sometimes be easier to get to a NEO (delta V wise) than to get to Mars or even the Moon. The radiation shielding will be similar to a Mars mission. The length of a NEO mission would probably be shorter than a Mars mission (I would imagine within the range of 90 days on the surface max) with travel times between the Earth and the NEO being less than to Mars. While I concur with your assessment of the gravity situation, I think that an NEO mission would be more of a Mars-light type of situation than a Moons mission. On the contrary, the major advantage of a Moon mission as a Mars training being the close proximity and rapid response to adverse situations that might arise.
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Jonathan Sharma