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 …
stir the tanks
I wonder how many people will get the reference.
Clue to the clueless, it relates to a US Apollo in teh '70s.
You obviously got it!! Well done!!!1!
That is all
Its always the way with weekend DIY. What should take a couple of hours ends up taking three days, a pair of shredded hands and enough curse words to make a pirate blush.
The difference is, you can't exactly nip to B&Q for a bigger 'ommer when you're on the ISS.
Does this remind you of those movies where the button to stop the engine exploding/self destruct is behind large spinning chopping or stamping blades?
Why are such vital organs on the outside?
Because there's not much room inside? Because if it does fail it's better to have ammonia squirting into space instead of into your face? Because the heat echange process works better in the cold of space instead of the relatively cosy interior of the space station?
....because in the event of a serious ammonia leak it really is better to vent the stuff into space rather than into the internal ISS atmosphere.
Nasty stuff ammonia, just ask Jack McKay...
The vital organs containing ammonia and heat exchangers and pipework and moving parts probably work best outside?
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?
Probably because no-one wants a leaking ammonia pump inside
"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.
"Because the heat echange process works better in the cold of space instead of the relatively cosy interior of the space station?"
Vacuum does not work like that. Keeping things cool in space is a REALLY big problem.
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.
I would love to see the leak forming snowflake-like patterns.
...turn easily at room temperature may need much more torque at darkside temps. Also, in the vacuum of space, anti seize coatings might evaporate.
Time for the 36-inch pipe wrench. I recall a similar issue arising with some panel screws on the Hubble upgrade.
And of course a big solar flare had to happen during this period. (worst time ever for a spacewalk...)
...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.
Good job Tracy and Doug, you people are heroes! Just wait until you get back to Earth, you can star in the movie! Keep up the good work! :)
(I know it's not fixed yet, doesn't matter, that's a tricky job in difficult circumstances, I reckon they already earned their medals)
Give a couple of wallops with some stilsons, that should shift it.
"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.
He'll get the job done with Mighty Fixit!
If it takes two astronauts to replace the pump, they obviously need three out there. The third one to put his thumb over the end of the pipe while the other two swap the box.
This is why yer average garage has a YTS trainee in the workshop. Well, that and making the tea......
If it is a three man job, how many blonde's would it take?
... Harry Tuttle!
@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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