Joined
·
1,449 Posts
Astronauts “Camp Out” to Prevent DCS
(Filed under: Uncategorized — scubadoc @ 4:37 pm )
Before they embarking on complicated spacewalks, astronauts on the shuttle mission “camp out” in the International Space Station’s airlock for the first time.
The aim is to prevent them from getting decompression sickness, also known as the bends, when they work in their spacesuits, which are at a lower pressure than the station.
Four of the shuttle Atlantis’s six crew members will participate in a total of three spacewalks, with two astronauts performing each spacewalk.
Decompression sickness can occur during spacewalks because the ISS is normally at a pressure of 101.3 kilopascals (14.7 pounds per square inch), but the pressure inside a spacesuit during a spacewalk is just 29.6 kPa (4.3 psi).
Dangerous bubbles
At the higher pressure inside the station, nitrogen in the air can dissolve in the blood and tissues, just as it does for divers in the deep sea. Moving too quickly to lower pressures can cause that dissolved gas to create bubbles and obstruct blood flow, which can sometimes be fatal.
Previously, astronauts prepared for a spacewalk on the ISS by exercising on a stationary bicycle and wearing an oxygen mask. Exercise helps purge nitrogen out of the bloodstream because it increases blood circulation, while oxygen – unlike nitrogen – is used by the body and does not build up in the blood and tissues.
But on this mission, the pairs of astronauts will spend the night before each spacewalk in the equipment lock of the station’s Quest airlock – which will be lowered to a pressure of 70.3 kPa (10.2 psi) – to purge nitrogen from their blood.
Quiet night
“This is a more relaxed approach,” says John McCullough, lead ISS flight director for NASA.
The campout method may actually save the spacewalkers about an hour of time compared to the exercise method, which the crew hopes will make the preparations for their 6.5-hour spacewalks less harried.
“I kind of like it,” says astronaut Dan Burbank, who will make his first spacewalk on the flight. “I like the idea of having a nice quiet night.”
They will do all of their grooming earlier in the night and they will be able to bring cold food into the airlock with them. But while camping out, if nature calls, they will have to use an adult diaper. In the morning, they will be allowed to return briefly to the main part of the ISS to relieve themselves and to grab some breakfast to take back into the airlock before their spacewalk.
The campout is similar to a process used to prepare for spacewalks from the shuttle itself, when it was not docked to the space station – for example, when astronauts serviced the Hubble Space Telescope.
Before those spacewalks, astronauts breathed 100% oxygen for one to two hours at 101.3 kPa (14.7 psi), then reduced the pressure of the entire orbiter to 70.3 kilopascals (10.2 psi) for 10 hours. Finally, they breathed 100% pure oxygen again for the hour just before their spacewalk.
(Filed under: Uncategorized — scubadoc @ 4:37 pm )
Before they embarking on complicated spacewalks, astronauts on the shuttle mission “camp out” in the International Space Station’s airlock for the first time.
The aim is to prevent them from getting decompression sickness, also known as the bends, when they work in their spacesuits, which are at a lower pressure than the station.
Four of the shuttle Atlantis’s six crew members will participate in a total of three spacewalks, with two astronauts performing each spacewalk.
Decompression sickness can occur during spacewalks because the ISS is normally at a pressure of 101.3 kilopascals (14.7 pounds per square inch), but the pressure inside a spacesuit during a spacewalk is just 29.6 kPa (4.3 psi).
Dangerous bubbles
At the higher pressure inside the station, nitrogen in the air can dissolve in the blood and tissues, just as it does for divers in the deep sea. Moving too quickly to lower pressures can cause that dissolved gas to create bubbles and obstruct blood flow, which can sometimes be fatal.
Previously, astronauts prepared for a spacewalk on the ISS by exercising on a stationary bicycle and wearing an oxygen mask. Exercise helps purge nitrogen out of the bloodstream because it increases blood circulation, while oxygen – unlike nitrogen – is used by the body and does not build up in the blood and tissues.
But on this mission, the pairs of astronauts will spend the night before each spacewalk in the equipment lock of the station’s Quest airlock – which will be lowered to a pressure of 70.3 kPa (10.2 psi) – to purge nitrogen from their blood.
Quiet night
“This is a more relaxed approach,” says John McCullough, lead ISS flight director for NASA.
The campout method may actually save the spacewalkers about an hour of time compared to the exercise method, which the crew hopes will make the preparations for their 6.5-hour spacewalks less harried.
“I kind of like it,” says astronaut Dan Burbank, who will make his first spacewalk on the flight. “I like the idea of having a nice quiet night.”
They will do all of their grooming earlier in the night and they will be able to bring cold food into the airlock with them. But while camping out, if nature calls, they will have to use an adult diaper. In the morning, they will be allowed to return briefly to the main part of the ISS to relieve themselves and to grab some breakfast to take back into the airlock before their spacewalk.
The campout is similar to a process used to prepare for spacewalks from the shuttle itself, when it was not docked to the space station – for example, when astronauts serviced the Hubble Space Telescope.
Before those spacewalks, astronauts breathed 100% oxygen for one to two hours at 101.3 kPa (14.7 psi), then reduced the pressure of the entire orbiter to 70.3 kilopascals (10.2 psi) for 10 hours. Finally, they breathed 100% pure oxygen again for the hour just before their spacewalk.
