"The Russians have been flying long duration crews since the early '70's. And in the early days, they've ended at least two missions early because of conflicts within the crew. So, they learned early on the importance of studying this and making sure you put the right crew together. Since we began our work together on the International Space station with the Russians in the early 2000's, NASA has started to learn the importance of this kind of work. And so, I think it's important work and we are not fully onboard and recognize it as important."