Spacewalkers Tracy Caldwell Dyson and Doug Wheelock have spent a frustrating eight hours, three minutes* outside the International Space Station attemping to swap out the ammonia pump which failed last Saturday night and knocked out half of the station's cooling system. Caldwell Dyson and Wheelock outside the ISS. Pic: NASA …
people, and inside the cooling equipment is ammonia. You want to keep as much of the ammonia and its pipes and pumps away from the people as you can possibly manage. I've lived in a place where somebody forgot to keep the ammonia contained - too fast around the curve on the overhead ramp that one - and you don't live long in that kind of cloud.
Give some credit to others for thinking until you've thought a bit yourself.
Or would you put the gas tank up front above/around the hot engine so that gravity feed would work, and then wonder why cars blew up every so often?
"Why are such vital organs on the outside?"
Why do people assume the design is bad? The outside part of the station facing the sun gets very hot, and the part not facing the sun gets very cold. Ammonia is just used as a cooling medium. Yes, you could put the pumps inside, but guess what happens if it leaks ammonia into your very finite air supply?
Because they are full of ammonia and when changes are made some leakage is inevitable, ammonia is not good for humans. The parts of the cooling system within the habitable space where the temperature is fairly stable use water so there's no problem if there's a small leak during repair. Ammonia is used outside where the system has to cope with +/- 140 degrees C or thereabouts.
I was watching it and the hammer was the FIRST thing I would have probably brought to bear. And swearing. Which is not good on broadcast TV.
What was REALLY cool was watching the ammonia leak out and form really nifty patterns and shapes as it sublimated away. Kind of like 3D snowflakes that were there one instant and gone the next. Even the astronauts said "cool!" even though ammonia leaking out was a Bad Thing.
...they omitted the stage where you soak everything you can reach in WD40 for a few hours. I have no doubts that something as insignificant as the cold of space isn't going to stand in the way of WD40's magical powers.
Paris, she understands the important of being well lubed before trying to get nuts off.
"The station is in a stable configuration with most systems receiving cooling and many systems operating with redundancy following the installation of jumper cables from the Destiny Lab’s power system overnight."
Why did someone forget to design proper redundant system for the cooling system? The above quote from NASA says to me that the ISS doesn't have fully redundant systems - 'many' and 'most' simply doesn't cut it when you can't just pop to B&Q for some gaffer tape to fix the issue.
That just pain sucks for the poor chaps who have to venture into space more urgently than if properly redundancy had been built into the system in the first place.
On the previous story but I got downvoted...hey ho... why not have the two pumps online? (already plumbed in) side by side all it would need are some oneway valves. then when it fails flick a switch to fire up the <s>quatro</s> alternative, then you have plenty of time to sort out replacement without loosing some (derrived from most and many) systems and without Power jumper installations. (So how much redundancy is there now?) lets just hope that the other coolant loops pump was manufactured and commissioned at a different time, we really don't want them both to fail at the same time.
There is redundancy and there is redundancy! IT guys learned this a long time ago, thats why we have Raid 5 AND an online spare drive. no point in having one sitting on the shelf.
@Keith_C, don't know if you're serious or not, but I've tried to use WD40 when it was about 0 degreees (fahrenheit) out. It doesn't work. I don't know how the vacuum would affect it but the cold isn't too great 8-).
Regarding the pump location, this is some kind of ammonia-based air conditioning. I don't think it's outside because of safety -- after all, there will be an indoor portion to the system too. Think of how an air conditioner operates though -- if you're removing heat, part of the unit HAS to be outside to operate as a heat exchanger. And, this is probably not merely a pump, but a compressor -- which is typically outdoors with the heat exchanger.
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