The data points that do exist for very long space flights suggest prolonged zero gravity should be avoided.
It's also why I don't see DSH as a serious concept and instead as mostly a political ploy.
Ploy - "a maneuver or strategem" with the purpose of . . . ?
You're discounting non-AG technologies that could help, such as stretchable suits.
What responsibilities would the crew have during the cruise phase of a Mars mission? It seems to me that boredom would be a dominant feature of that transit.
Cooking could help relieve the tedium of a transit lasting several months with essentially nothing to do (unless something goes wrong).
On the other hand, once on the surface of Phobos or Mars time spent cooking would be time not available for exploration (or sleeping).
What responsibilities would the crew have during the cruise phase of a Mars mission? It seems to me that boredom would be a dominant feature of that transit.
An interesting question that has come to mind in connection with lunar outposts also. After you've got done with primary duties (collecting rocks and the like), secondary but vital ones like maintaining the station, what do you? Read, watch movies, play poker, take correspondence courses, surf the Web and so on, I suppose.
I trust that any Mars expedition will have a bunch of terabytes of storage on board and a wide-band link to earth, so their information needs will be pretty well taken care of. Speed of light lag would rule out Skype, but email should be just fine and Google work on local databases and, with lag, those back on Earth.
Every Mars mission is planned with no centrifuge. Too short of duration to need one.
Well that is not entirely correct most Mars mission concepts do have some sort AG usually a tether or in the case of the last serious study the BNTR concept the entire ship acted as a centrifuge during cruise.
Also Mars direct used the old discarded departure stage as a counter weight for ag.
DSH is extremely early and what is shown probably will never fly let alone go to Mars.
So Jim is wrong again? 
Again?
Actually, Mars Direct was without AG, but it was an option
And I was talking about plans in the last few years, like ESAS
I'm still waiting for Jim to back up his supremely confident assertions w.r.t. zero-g space laundry and the packaging efficiency of prepackaged food vs. bulk cooked food. It sounds like there's been some research/experiments done that I'm not aware of, and as I said, I am genuinely interested to learn more...
Depends in part on mission duration; e.g., current thermostabilized pre-packaged shelf life can be a problem beyond ~18mo. There have been numerous studies over the last decades on various food packaging options and tradeoffs, from various forms or pre-packaged to bulk. A good (and recent) article with lots-o-references:
Developing the NASA Food System for Long-Duration Missions, Journal of Food Sience, Mar 2011
There is also a project that started in 2010 and is suppose to run for two years to look at various options, including "Trade Study – Food Processing vs. Packaged Food System". Not sure if it's still going but they haven't published anything that I can find; see:
NASA Advanced Food Technology Project
It's drifting off topic a bit to point this out, but just about every terrestrial clothes washing machine uses a centrifuge and artificial gravity during its spin cycle....
Again?
Actually, Mars Direct was without AG, but it was an option
And I was talking about plans in the last few years, like ESAS
I read some of Zurbin's published reports including several of his books on the subject and a lot depended on findings on whether or not would Mars gravity be enough to get the crew back into shape after the five to six month trip out.
One reason for the later Mars gravity biosatellite concept was to answer those question which we still don't know.
http://en.wikipedia.org/wiki/Mars_Gravity_BiosatelliteI think a Dragon lab should be purchased for Mars gravity research as it might be the cheapest possible way to do that research.
We really don't have any data on the effects of partial g on mammals.
Without that data you pretty much have to error on the side of crew health.
As for the ESAS plans they seemed to be ignoring an entire herd of elephants in the room.
Plus pretty much ignoring the fact orbital rendezvous and assembly is routine now.
In short it looked like a Mars mission concept from the 1970s.
There have been numerous studies over the last decades on various food packaging options and tradeoffs, from various forms or pre-packaged to bulk. A good (and recent) article with lots-o-references:
Developing the NASA Food System for Long-Duration Missions, Journal of Food Sience, Mar 2011
Quite an interesting paper, with lots of useful numbers. Thanks for pointing it out!
A couple additional references from the archives that may be of interest, albeit somewhat dated (I need a better memory or a better indexing system).
These include discussion and evaluation of advanced vs. baseline life support technologies (e.g., food, clothing, waste management, etc.) for various mission classes (e.g., ISS, lunar, mars transit, mars surface, etc). The second provides additional info on some of the evaluation metrics and their assumptions and derivations.
Advanced Life Support Research and Technology Development Metric, NASA CR-2006-213694, 2006
Advanced Life Support Baseline Values and Assumptions Document, NASA CR-2004–208941, 2004
... If the Prometheus project is any indication, whatever advantage reactors confer comes at quite a cost! Also isn't there a problem with using a NTR reactor for electric power generation? It certainly is different in design than reactors designed for electric power production.
Have a look at the PWR Triton tri-mode reactor concept. Operates at about 1% of the full NTR power mode to produce about 25 kWe. That's a little more than the max continuous output of the Space Shuttle's 3 fuel cells combined.
At 15klbf (30klbf with LOX augmentation) a Deep Space vehicle leaving L1/2 might use several to reduce gravity losses, and increase propulsion & power redundancy later in the mission.
As well as providing DSH power, they could also supply conventional ion drives for course correction and to speed up the trip. IMO a VASIMR is not necessary if you already have a high thrust engine.
Looking at the pdf in the OP, I'm wondering about the hardware that gets discarded. Sticking to just the NEO missions, at the end, the SEP and the DSH get discarded. It might just be beyond the scope of this paper, but could they be saved? Could they be parked in a high orbit and be available for some future purpose? could the SEP slow down the craft on the return trip to lower that 11.8km/s velocity (while also extending the trip to greater than 210 days however)?
