When astronauts go into space...how do they breathe air?

Question

Don,t tell me they have a bottle of air each.

Answer 1

Pressurised air, like in a submarine..

Answer 2

The answer to this question is a bit more complex than it sounds. The human mechanism for absorbing oxygen starts when we inhale. Normal air is about 20% oxygen and the rest is mostly nitrogen. This means that of the 15psi in normal air, we need around 3psi of it to be oxygen for normal breathing. The law of partial pressures tell us that we should be able to have just 3psi of oxygen and be ok, but unfortunately we need it to be pressurized at at least 5psi to give it enough oomph on the way in for our red blood cells to grab hold of it.

So, in a space suit, they generally breath a mixture of oxygen and something else to bring the total up to 3psi of oxygen, and another 2psi of something else. The oxygen originally comes from a bottle, yes, but most of it gets recycled over the time that a person uses it. Rebreathing apparatus cleans the air and cycles it back through for reuse.

In the space station it's a little different. They breathe a full atmosphere there. Oxygen is generated from splitting water into O2 and hydrogen using electricity generated from solar power. Carbon dioxide is scrubbed from the air using an industrial sized version of the rebreathing apparatus.

Answer 3

The shuttle has a reformulated 'air' that is 80% nitrogen and 20% oxygen, essentially the same composition as normal Earth air, save for the lack of gasses that are present in trace amount on the planet. The same applies to the ISS. The Apollo spacecraft that went to the Moon were pressurized with pure oxygen at about 1/3 the pressure of air, this saved on the gauge and strength of the material needed to contain the pressure, as well as saving the weight of the nitrogen gas itself (the Lunar Lander, for instance, was depressurized before going out on the Moon by venting the oxygen out. When coming back in, the astronaut simply filled it with "fresh" oxygen from the supply reservoir, a much simpler and lighter solution than pumping away the gas to a tank).

Answer 4

Contrary to what others have said (although I think they deleted their answers), the lung is NOT a muscle. It is the diaphragm that draws air into the lungs. When the diaphragm contracts it creates a negative pressure in the plural cavity. This is the sack in which the lungs sit. Since the air we breathe has pressure (14.7 lb/sq-in at sea level), that positive pressure pushes air into our lungs to fill the negative pressure. Therefore, where ever someone is breathing, the outside pressure must be higher than the internal negative pressure in the plural cavity.

And actually, when astronauts venture out in a space suit, they pre-breathe pure oxygen for sometime before donning their space suits. This is because the space suits are not fully pressurize at 14.7 lbs/sq-in (sea level pressure.) The suits have a pressure that is much lower than that to reduce the outward stress on the suits and also make it easier for the astronauts to move around and work the suit and gloves. Since the suits have a lower pressure, NASA doesn't want the astronauts to get the "bends" and therefore they pre-breathe oxygen to help expel as much nitrogen gas from their blood. But the pressure in the suits is still greater than the negative pressure created by the diaphragm and air is pushed into the astronauts lungs.

The air pressure in the space vehicle must also be greater than the negative pressure of the diaphragm for the astronauts to breathe. However, I am not sure if it is sea level pressure or less. I would think that it is less, since any punctures in the hull would vent air out much faster at higher pressures and could also lead to a catstrophic failure. Further, if humans can breathe at a lower pressure, there is no need to keep it as high as 14.7lbs/sq-in.

From the link below:

"Crewmembers must spend several hours prior to each spacewalk breathing pure oxygen from a face mask. This procedure, called pre-breathing, minimizes the chance that astronauts will suffer from the decompression sickness, commonly called "the bends". The bends are painful and dangerous cramping caused when nitrogen bubbles in the bloodstream become trapped in joints and organs such as the brain.

The time spent pre-breathing pure oxygen is partly dependent on the pressures established in the Shuttle cabin and in the space suits. NASA life sciences researchers have developed procedures to maximize astronaut safety and productivity and to minimize the time spent pre-breathing oxygen.

EVA preparations begin the day before, when the equipment is checked out by the astronauts to make sure that everything works properly. Also, the pressure inside the crew cabin is lowered from 14.7 psi to 10.2 psi. Time spent at 10.2 psi purges nitrogen from the spacewalkers' bodies and prevents decompression sickness when they go to the 4.3 psi pure oxygen atmosphere of a spacesuit. The spacesuit is kept at a low 4.3 psi pressure so that it remains flexible.

About 2.5 hours before the extravehicular activity begins, the astronauts start to breathe pure oxygen during the pre-breathing activity. This pure oxygen washes out the nitrogen dissolved in the blood. "

Answer 5

Hi. Inside of a space suit, yes. They have a bottle of air each.

Answer 6

One of the principle fuels they carry is Liquid Oxygen, which they use to make water (through fuel cells, burning hydrogen with it), and vaporize it for breathing.

Remember the movie "Apollo 13"...? One of two large Liquid Oxygen tanks exploded, causing their problems. Every manned craft ever launched has a one or more tanks of oxygen.

Answer 7

A spaceship is full of pressurised air.

If they go out into space, they do indeed have a bottle of air each.

Answer 8

D shuttle is like an airtight bottle & has a fixed flow of oxygen

Answer 9

Just like when scuba divers go underwater for long periods, the space shuttle is equipped with compressed air. Eash spacesuit also has its own oxygen supply.

Answer 10

You guessed it.
a bottle of air each.

Inside the shuttle it is a pressurized cabin with several more bottles of air and an O2 scrubber.