>They run a lean team Isn't this at odds with your previous comment about redundancy being a no-brainer? He was a principle engineer in an optics lab. Having

>They run a lean team Isn't this at odds with your previous comment about redundancy being a no-brainer? He was a principle engineer in an optics lab. Having worked in both optics labs and aerospace, I can say there is very little reason to think that a "bad back" in those roles puts astronauts at additional risk.