>> one thing that is really important is we are evaluating how to keep scott are losing what wehile he have learned over the last three or four years on the space station is that some astronauts lose some of their vision while they are in space, but some do not. some astronauts, when they come home, that asian losses permanent, and in a few individuals it is severe. we have i have a hypothesis about how that is happening. it has to do with the fact that when you're in gravity, all of the blood flows into your legs. your heart has to pump it back up. when you're in space, all of that flows into your head. we know how big or as puffy. we think that is putting pressure on the brain and on the optic nerves. it compresses the eyeball, and can damage vision. so to study that on the space station, both scott and his --ments not counterpart cosmonaut counterpart are doing a series of eye exam and we are putting them in a russian device which is a lower body pressure device. out of thee fluid top of their body and down into the bottom of their body and we're able to use our ultrasound to look a