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Everyday Astronaut: Interview with the Polaris Dawn Crew (youtu.be)

submitted 6 months ago by [email protected] to c/[email protected]

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[–] [email protected] 8 points 6 months ago (2 children)

Interesting facts from the video:

100% oxygen only in the suits, not in the capsule
suit pressure above 5 PSI. The suits have to be pretty good to keep mobility with this pressure!

[–] [email protected] 8 points 6 months ago

Great interview, this tech demo is going to neat to hear the results.

I was really curious how they fit an airlock in the capsule, but then they started talking about the whole thing being depressurized.

Then using the EVA suit as the IVA suit?

They're really going all in on this, hope nothing goes wrong, cause there's not a lot of room for error. Even with all the redundancy.

Would be outstanding if they are really able to service Hubble after they get the tech worked out.

[+] [email protected] -9 points 6 months ago (4 children)

100% oxygen in the suits would cause them to spontaneously combust.

But ok. Whatever.

[–] [email protected] 6 points 6 months ago (1 children)

Pretty much all modern EVA suits (like the ones used by US, China, Russia) run a pure oxygen at about .20 ATM so that the internal pressure is lower but the amount of oxygen the astronaut is breathing is the same density of oxygen as at 1 ATM. This allows much better maneuverability in the space suit, because any air mixture at 1 ATM makes it nearly immediately to move in a space suit (they become too stiff).

Point is, we have been doing spacewalks like this since spacewalks started and no one has spontaneously combusted on one.

[–] [email protected] 4 points 6 months ago* (last edited 6 months ago)

Ok fair enough. My dilettante knowledge of chemistry let me down.

A little bit of knowledge is a dangerous thing, unlike pure oxygen at only a little bit of pressure.

[–] [email protected] 3 points 6 months ago

With 100% oxygen you will be fine down to 4 psi or so. Mixed gas would need substantially higher pressure and that would likely make those suits too stiff to move.

[–] [email protected] 3 points 6 months ago (1 children)

That’s what they said in the interview. And didn’t Apollo also had a pure oxygen environment? As long as there isn’t a spark it wouldn’t combust, right?

[–] [email protected] 3 points 6 months ago (1 children)

Even the command module was pure oxygen at 5 psi. There was the Apollo 1 fire, but otherwise I don't remember that there were any major issues.

[–] [email protected] 3 points 6 months ago (1 children)

The pressure in the Apollo 1 capsule was 16.7 PSI or 1.14 atmospheres of pure oxygen. That's almost 5.5 times the partial pressure of oxygen at sea level. At 5 PSI, the Polaris crew will only be at 1.6 times the partial pressure of oxygen at sea level.

[–] [email protected] 2 points 6 months ago (1 children)

You're right, the Apollo 1 was significantly higher pressure. Didn't know that. 😲 Makes somewhat more sense they could keep a pure oxygen atmosphere even after the accident.

Also, calculating partial pressures in psi is really annoying.

[–] [email protected] 2 points 6 months ago

kPa and Bar are obviously superior units!

[–] [email protected] 2 points 6 months ago

100% oxygen doesn’t cause humans to spontaneously combust. It does make them more flammable, but that’s already controlled for in spaceflight.

[–] [email protected] 3 points 6 months ago (2 children)

23:23 "Most of the IVA suits have an inseam zipper ..."

Just checking that everyone (who wants to) has seen this in action. Here's Sultan Al Neyadi putting on his IVA suit without assistance while on the ISS. (32:49 to 38:12.)

Is anyone aware of a better video of the suit than that?