I disagree, at least in the extent to which survival at the end of the trip (be it one way or not) is not a reasonable probability. It's not as simple as "do you want to take that risk?" Risk implies probability, but planning for a one-way trip is a certainty.
An organization does not have the ethical right to ask for this certainty, especially when there is no chance that the asking could be done without some form of coercion (i.e. implicit do it for your country/honor/science/show you're not a coward/etc...). We don't even ask this of our armed forces. When people join, they know there's a risk (i.e. probability) that they may die - and in fact that they may later be ordered into a very bad situation - but those are situations (often in the heat) where plans went very wrong, or situations involving the kind of math where you spend infinity to gain infinity. And even in that example, the action was voluntary by situation, not by designed plan. We have no such pressing desperation in scientific exploration.
We can design exploration plans that allow for something other than suffocation or starvation as an end point. I would say that exploration with pioneering and settlement are ethically reasonable places to solicit volunteers. Even sustained exploration where limited resources are not an assurance of death (i.e. "an ongoing mission to seek out...") could be reasonable. But I think any mission which involves planting a flag, running a few experiments, and then opening one's helmet is ethically flawed - especially when patience will let us solve the intrinsic survival problems.