NASA astronauts test new exercises on space walk

May 25, 2011
Two astronauts, Drew Feustel (pictured) and Mike Fincke, have floated out of the International Space Station after trying out new exercises aimed at preventing decompression sickness while conserving oxygen, NASA said.

Two astronauts floated out of the International Space Station on Wednesday after trying out new exercises aimed at preventing decompression sickness while conserving oxygen, NASA said.

"Drew Feustel and Mike Fincke switched their suits to battery power at 1:43 am EDT (0543 GMT), signifying the start of today's planned six and a half hour excursion," the US space agency said in a statement.

The two astronauts completed a new set of light exercises aimed at preventing known as "the bends," a condition that can afflict scuba divers if they rise to the surface too quickly.

The combination of breathing and low-effort exercises, known officially as the in-suit light exercise prebreathe protocol and informally as the "slow motion hokey pokey," is intended to purge nitrogen from the bloodstream.

The failure to do so could lead to the formation of as they stroll through space, causing pain in the joints or, in rare cases, paralysis or death.

On the eve of the past 70 spacewalks, astronauts have camped out overnight in an where the pressure is 10.2 pounds per square inch, in between that of the space station (around 14 psi) and the spacesuits (about 4 psi).

The new regimen is aimed at helping to conserve oxygen at the space station, which will be important once the ends later this year and Russian spacecraft are the only vehicles equipped to resupply the lab.

The space walk -- the third of four scheduled during the Endeavour shuttle's final mission -- is aimed at completing an external wireless antenna system and mending parts of the Russian side of the space station.

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Mayday
not rated yet May 25, 2011
I had no idea that the air pressure in a spacesuit was so low. Can someone confirm the 4 psi figure. That's the air pressure at 30,000 feet. I know they're breathing an oxygen-rich mixture, but I thought the air pressure was higher. Wow.
Mayday
not rated yet May 25, 2011
I had no idea that the air pressure in a spacesuit was so low. Can someone confirm the 4 psi figure. That's the air pressure at 30,000 feet. I know they're breathing an oxygen-rich mixture, but I thought the air pressure was higher. Wow.
Mayday
not rated yet May 25, 2011
Sorry for the double. And I was able to confirm that the number is right. The 4psi allows the astronaut to be oxygenated at about the level of a passenger on a normal commercial flight, or the equivalent of a little above 6,000 feet altitude.
Temple
not rated yet May 26, 2011
I was able to confirm that the number is right. The 4psi allows the astronaut to be oxygenated at about the level of a passenger on a normal commercial flight, or the equivalent of a little above 6,000 feet altitude.


The reason that the pressure is that low is mostly to allow movement.

Despite it's extremely close fit and serious complexity, the astronaut's space suit is essentially still an inflatable bag. The pressure in the suit is also the pressure differential between inside and outside the suit (obviously). When moving the joints, the astronaut is effectively compressing the suit, reducing the volume, fighting against suit pressure to do it.

Even at a fairly low 4psi, it takes effort to even close the hands. Astronauts who have done long EVAs have talked about how difficult it is just to hold onto tools for long hours, all the while fighting against the internal suit pressure, which wants to keep the gloved hand open.

Greater pressure would make it impossible to move.