Summary: 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. 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, try this fun game. Turn on your computer and start playing a game. Something awesome like Starcraft II. After an hour or so put your hand behind the computer and feel the warm or in some cases hot air coming out of the back. Now multiply that by 10 or 100 and you have the heat generated just by some of the equipment in the ISS. 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 ISS 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 stations truss. Think of the ISS as a giant water cooled gaming PC. Only, theres no real time battle.net connection and the lag is insane. 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 0000 Universal Time on August 1st, 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 wasn’t 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 an 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. Loop B is still operational, however it can only dissipate heat where its ammonia lines pass, so not all of the instrumentation on the space station is being cooled. This means that some equipment has been 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 what they want to do next.
