The Moon - forty years later

[FoolKiller]

Those are all problems for any long-term manned mission, return or otherwise. Atleast a one-way mission would mean that you could spend alot longer at the site of interest rather than spending most of the time in transit.

True, although depending on the type of mission (keep flying until you die, land and live on a planet, or come back home an old man) will determine to what degree each aspect will affect the mission. Knowing you will return home can affect the psychology. Landing on a planet/moon to stay will reduce the atrophy problem and gives you an on-ship goal to prepare for their new home. Deep space flight means you can't even hope for a renewable resource.

The real question is whether there is any point in having manned missions at all, and increasingly the answer is no. As Dan alludes to, as technology advances, unmanned missions are as capable of providing data than manned missions. Still, IMO there will always be the need for manned missions, not least because Mankind might have to think about finding other abodes in future. But the options are stark - either consider a permanent culture in space, or consider changing human longevity itself.

Manned flights must be maintained just to be prepared for the instance that an unmanned mission discovers something that would necessitate a manned mission. Also, people tend to ignore unmanned missions and if you quit putting men in space then men will quit giving you money.