Live ISS coolant pump replacement spacewalk

Wonder what the exposure will be like.
I doubt I'd have the courage to make the trip up, let alone doing an EVA. I'd be terrified.
 
Bummer, good video then a blue screen, and they lost the live feed from the ISS showing the actual repair operations. I've got my fingers crossed.
 
Yay!!! video is back up!

For me, the claustrophobia would destroy me on that trip back in the little capsule. I get queasy just seeing those guys get pulled out.
 
Well, they may have to work on Christmas, but at least they got some (ammonia) snowflakes on 'em.
 
Every time I see a spacewalk, I have to marvel anew at how back-asswards retarded the suits are. I get that they're an iterative design stemming back from high-altitude flight suits, but damn. Pretty much the only part of the suit the astronauts use is the hands, yet every bit of them are swaddled in a suit where each patch needs its own heating/cooling, they can't do a thing in case of a tear, and they can't even scratch their ass for five hours. Surely there must be a better way to do this?
 
Today's walk is over now. I was very curious to see if Mission Control would break into a cheer, as is required by narrative convention.

One guy at the front of the room clapped a little. Everyone else kept staring at their stuff.
 
Beelzebuddy said:
Every time I see a spacewalk, I have to marvel anew at how back-asswards retarded the suits are. I get that they're an iterative design stemming back from high-altitude flight suits, but damn. Pretty much the only part of the suit the astronauts use is the hands, yet every bit of them are swaddled in a suit where each patch needs its own heating/cooling, they can't do a thing in case of a tear, and they can't even scratch their ass for five hours. Surely there must be a better way to do this?
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Well, the alternative is a tiny spacecraft; A hard suit. Those are much less well developed.
 
Frozen ammonia snow flakes from tubing may have contaminated space suits. They will have to go through a decontaminating procedure before reentering the ISS. I don't understand why frozen (-77C) ammonia would not simply vaporize or sublime on exposure to sunlight.

ETA: 5h 17min into space walk
 
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Olowkow said:
Frozen ammonia snow flakes from tubing may have contaminated space suits. They will have to go through a decontaminating procedure before reentering the ISS. I don't understand why frozen (-77C) ammonia would not simply vaporize or sublime on exposure to sunlight.
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It does, that's part of the procedure - a "bake out" is a long process of sitting in the sun doing bugger all while the ammonia evaporates off your suit. Depending on the amount of ammonia on your suit it can take a long time.

The suits have the long duration CO2 scrubber tanks on them, I believe the limiting consumable currently is the battery in the suits, but they could use an umbilical to get power from ISS directly.
 
Fishstick said:
It does, that's part of the procedure - a "bake out" is a long process of sitting in the sun doing bugger all while the ammonia evaporates off your suit. Depending on the amount of ammonia on your suit it can take a long time.

The suits have the long duration CO2 scrubber tanks on them, I believe the limiting consumable currently is the battery in the suits, but they could use an umbilical to get power from ISS directly.
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Thanks.

Is there any compelling reason why freon could not have been used instead of ammonia?

From this list of pros and cons, it seems like "requires less electricity" would be the main motive.

As a refrigerant, ammonia has four major advantages over CFCs and HCFCs:

  • An ammonia-based refrigeration systems costs 10-20% less to build than one that uses CFCs because narrower-diameter piping can be used.
  • Ammonia is a 3-10% more efficient refrigerant than CFCs, so an ammonia-based system requires less electricity, resulting in lower operating costs.
  • Ammonia is safe for the environment, with an Ozone Depletion Potential (ODP) rating of 0 and a Global Warming Potential (GWP) rating of 0.
  • Ammonia is substantially less expensive than CFCs or HCFCs
There are two key disadvantages to using ammonia as a refrigerant:

  • It is not compatible with copper, so it cannot be used in any system with copper pipes.
  • Ammonia is poisonous in high concentrations. Two factors, however, mitigate this risk: ammonia’s distinctive smell is detectable at concentrations well below those considered to be dangerous, and ammonia is lighter than air, so if any does leak, it will rise and dissipate in the atmosphere.
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Olowkow said:
Thanks.

Is there any compelling reason why freon could not have been used instead of ammonia?

From this list of pros and cons, it seems like "requires less electricity" would be the main motive.
Click to expand...

In addition to those advantages, Ammonia is also less viscous so it's easier to pump around, and has a greater thermal range (i think).
 
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