WEBVTT

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MS. STILSON:  Martine from Midlothian. We understand that each EVA is scheduled for six and a half hours.

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Is an EVA extremely fatiguing for the two astronauts and do they have backup EVA suits? Can you compare EVA's to scuba diving?

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MS. HIRE:  For the EVA, our crew members train for years for this, and it is very physically demanding. And the reason is,

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the EVA, or extravehicular activity, or spacewalk, is actually performed in a special suit that is pressurized.

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and outside of the suit is the vacuum of space.  This suit is a spaceship in itself.

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It has its own cooling system, all these different systems that operate on its own that the astronaut is only attached

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to the Space Shuttle or the Space Station by a tether, not by a tube that's feeding power or water or cooling or anything

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like that. So it's a very complicated suit. But the suit is pressurized. If you'll think about, if you've ever had your blood pressure taken

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and when they inflate the blood pressure cuff on your arm, that type of pressure. If you think about the little blood pressure cuffs

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around each and every finger and around the majority of your body, that's what it feels like.

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So just to move your fingers back and forth like this, you're pushing against that pressure.

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So it actually uses every little muscle and it is quite fatiguing. We practice this and almost choreograph these EVA's

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or space walks ahead of time just for that reason. As far as backup suits, we don't typically fly a backup suit.

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We will have some spare parts if we need them. And on this mission, we are carrying four space suits, but that's because two of them are going

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to be left behind on the International Space Station. So in this mission,

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it's a little unique and we might have some extra spare parts if we needed them. But for a full-up spare suit, we typically do not fly them.

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MS. STILSON:  Understood.

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