There are many important Human Factors Engineering issues involved in multi-generational starship design. One basic issue is Neutral Body Posture, which is defined as the posture the human body naturally assumes in microgravity and is similar to the fetal position. It is important to note that in this position, each joint is at or near the midpoint of its range of motion--the point at which each set of muscles is able to exert the most force. If any portion of a long-term starship will experience the effects of zero-gravity, tasks performed in that part of the ship must take this posture into account. Proper Restraint and Mobility Aids such as foot restraints and handholds assist the crew members in maintaining this posture. It may seem like a minor detail in the design of a multi-generational tarship, and perhaps for generations born on the ship, such considerations do indeed become minor, but for older members of the first generation to become star travellers, this is crucial.
Another piece of microgravity trivia is that the human spine stretches two inches, making people two inches taller in microgravity. The constant gravity load on the spine is removed; nifty, futuristic, lycra uniform designers better remember this!
And of course, the psychological issues are many. I know they've been
bounced around in the newsletters, and everyone has their own opinions.
The basic, umbrella Human Factors concepts involved are workload and
personal space. Traditional workload issues include keeping the crew
member busy enough to feel valuable to the mission without overworking
and stressing him/her. I know the idea of having crew members who
perform multiple duties was pretty much agreed upon in earlier
newsletters. This would help keep everyone busy and feeling valuable.
Personal space is the other big issue. A multigenerational starship
goes way beyond the longest submarine tour of duty. People could easily
go batty, technically speaking :). Another idea bounced around in
the newsletters has been to tether two ships to each other with some
sort of tunnel and switch out crewmembers at a certain time. This makes
sense to me. If people know at a certain mission elapsed time they will
be switching ships, it gives them something to work toward and a major
change of scenery. Or the second ship could be storage and "vacation
space." There are many possiblities with that design; is it
technologically feasible? That's for the other engineering disciplines
(Picture from R. Dale Huchingson's New Horizons for Human Factors in Design)