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Ammonia Pump Spacewalk Problems - SpacePod 2010.08.09

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The International Space Station is trying to keep it cool with what may now amount to 3 spacewalks, on your SpacePod for Monday August 9th, 2010. The first spacewalk to repair the ammonia coolant pump failed, putting a possible third unplanned spacewalk on the schedule. This is all part of the continued TROUBLE ON THE ISS! Overly-dramatic opening aside, here's what is really going on. The ISS needs to dissipate heat. Now, while you may think that it's really cold in space, and by the way it is, the equipment on the ISS can get quite hot. To show you how much, let's try this fun experiment: Turn on your computer and start playing a game. Something awesome like Starcraft II. After about an hour or so put your hand behind the computer and feel how warm, or in some cases hot, the air coming out of the back is. Now multiply that by 10 or 100 and you have the heat generated by just some of the equipment in the ISS. Now, unlike here on Earth you can't just blow the hot air outside, or at least out of your room. If they did that in space, they would suffocate. So instead a method to transfer the heat to something else is required, and that's where ammonia lines that run all through the International Space Station come in. These ammonia lines are used to collect heat, move it away and reject it via a couple of built in radiators on the station's truss. Think of the ISS as a giant water cooled gaming PC. Only, there is no real time battle.net and the connection lag is insane. Now, to ensure that mass chaos does not erupt if the coolant system ever goes down, it is separated in to two parts: Loop A and Loop B. Clever naming, I know. At around Zero Hundred Universal Time on August 1st 2010, the Loop A pump was knocked out with what NASA engineers suspect was a power surge. The ammonia cooling system is in two parts, one partly inside the ISS and the other partly outside. The pump they need to replace is outside which required at the time two different spacewalks. That was until the spacewalk that happened on Saturday lasted over 8 hours and was not a success. NASA Astronauts Douglas Wheelock and Tracy Caldwell Dyson had attempted to remove and replace the broken pump on their EVA or Spacewalk this last Saturday but they were plagued with setbacks. There was a stuck ammonia hose and a bit later on the ammonia leak, which by the way is not a good thing. That resulted in the pump not being replaced. This was only the first of the two planned spacewalks to get the pumps working again, but since it didn't go quite as well as planned NASA believes that a third spacewalk will now be required. NASA Engineer: So to just describe a little bit about what happened and what went wrong: This is a 1.5 inch quick-disconnect. This is similar to three of the four quick disconnects the crew was interacting with today. The other two of this size de-mated without much problem at all. These are known to be somewhat tricky sometimes, and I'll show some motion of this. Basically this is going toward the valve-closed position and what can happen ... well, the first time we came to the closed position we saw a little bit of a leak and the troubleshooting for that because we don't want to de-mate this and have a leak going constantly if it's from the female side ... so the troubleshooting that we had in place was to re-open the valve to try to cycle the seals on both sides of the quick-disconnect, both the male and the female. The male I don't have with me here today. When we did that, we got the valve back to the full open position and you can see this detent button here pops up to hold it all locked in place. There are two seals inside of this quick-disconnect, a primary and a secondary seal. We know that one of those seals leaks a little faster than the other and when they build up if they leaked too much ammonia between those two seals, you can get a hydraulic lockup in here, which puts a lot of force in the backward direction on this bale handle, which keeps you from being able to push this button down, it preloads this button so then you cannot re-close the valve. So, that is the condition that we got in today. Ben: Now, loop B is still operational, however it can only dissipate heat where its ammonia lines pass, so not all of the instrumentation and equipment on the space station is being cooled. This means that some equipment has to be shut down until Loop A can be repaired. Hopefully that will happen sooner rather than later. The next planned EVA or Spacewalk is set for this Wednesday but may be delayed as NASA engineers try and figure out exactly what they want to do next. Now if you would like to discuss this further, feel free to add a comment right here on SpaceVidcast.com or right on our Youtube channel. Or better yet, join us at the next Space Un-Conference.

Video Details

Duration: 5 minutes and 22 seconds
Year: 2010
Country: United States
Language: English
Producer: Benjamin Higginbotham
Director: Benjamin Higginbotham
Views: 97
Posted by: spacevidcast on Aug 9, 2010

The International Space Station is trying to keep it cool with what may now amount to 3 spacewalks, on your SpacePod for Monday August 9th, 2010.

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