Vacuum of Space

[gamowin]

I have but one question about spacecraft: How do they stay pressurized? Since all pressures try to balance to an equal point almost like heat, and space is an infinite vacuum, then how does anything remain pressurized?

[Awaras]

Because they are airtight?

Joking aside, no air seal is ever perfect, and all space craft slowly (very, very slowly) leak air into space. Still, it would take years for all the air to leak out.

[K^2]

It's not even just about leaks. Air will diffuse out if there are no leaks. And even metal of which the craft is built will eventually evaporate away. But like Awaras said, these things take really, really long time.

[DerekL1963]

Joking aside, no air seal is ever perfect, and all space craft slowly (very, very slowly) leak air into space. Still, it would take years for all the air to leak out.

How long it takes to leak depends on how much effort is put into sealing... the early Mercury capsules leaked up to 80cc/min! That was no problem with the shorter missions, they carried enough reserve O2 to make up for the leaks, but Faith 7 had to be heavily modified in order to remain in orbit for 24 hours.

[magnemoe]

How long it takes to leak depends on how much effort is put into sealing... the early Mercury capsules leaked up to 80cc/min! That was no problem with the shorter missions, they carried enough reserve O2 to make up for the leaks, but Faith 7 had to be heavily modified in order to remain in orbit for 24 hours.

Another reason for airlocks, the dual doors reduce leaks and add safety.

However 80cc/min is a lot, however it might simply be that they did not bother as it was inside requirements for the missions.