Space Station Cooling System Shuts Down


One of the International Space Station’s external cool system pumps quit working late Saturday, likely due to mechanical failure. This triggered subsequent shutdowns in other systems. Teams on the ground are working with the six astronauts on board the station to troubleshoot the issue, but it appears at least two spacewalks will be required to remove and replace the pump. NASA officials said the problem will have to be resolved quickly, as the cooling system is extremely important for all the station’s systems. This is a redundant system, so the backup loop is now cooling the station and the crew is in no danger, but NASA does not like to work any systems “single string,” i.e., with no backup.

NASA tried restarting the pump Sunday morning, but it did not work. There are two spare pumps on orbit. ISS astronauts Doug Wheelock and Tracy Caldwell Dyson had been already scheduled to make a spacewalk on August 5 to install part of a robotic crane and to do preparation work get ready for a new module (the Permanent Logistics Module) that is due to arrive in November aboard space shuttle Discovery.

EVA teams are now looking at using the August 5 space walk for the first half of the repairs, followed by the second EVA on August 7 (Saturday). The spacewalks need special planning since the system is in a reduced power configuration.

One of the radiators which allow for cooling on board the ISS. Credit: NASA

The space station features two independent coolant loops that use ammonia circulating through huge radiators to dissipate the heat generated by the station’s electronic systems, primarily from the labs. Each loop is fed by a large tank of ammonia that includes an internal bellows pressurized by nitrogen. That pressurization system allows the loops to handle the periodic expansion and contraction of the ammonia coolant due to temperature changes when the station goes from sunlight to shadow while in orbit.

Back in April a valve failed on the coolant system, but the teams were able to troubleshoot and fix the problem without a spacewalk.

A status update from NASA listed several other systems that required powerdowns to as a result of the cooling loop shutdown in order to thermally protect them:

Redundant power to four CQs (Crew Quarters), three in Node-2, one in Kibo JPM, with both fans in each CQ remaining functional but zero fault-tolerant (crew is still Go for CQ use). Due to loss of heater power, MBS (Mobile Base System), SSRMS (Space Station Remote Manipulator System), and SPDM (Special Purpose Dexterous Manipulator) are currently zero fault-tolerant. Communications systems, but there could be some issues with possible overheating. No video will be available fromNode-2, Node-3, the Columbus and Japanese modules.

8 Replies to “Space Station Cooling System Shuts Down”

  1. Wow those cooling units are pretty big and expensive. Two spares, now one. Stations going to be around till at least 2020. I’d be a little more secure on the space station if I could get those units repaired. Hard to do in space. I know – return to earth for EZ repair!! Use the shuttle to repair and return. What a great idea – anything to big to fix in space can be R and R’d!

    But wait. the shuttle is being cancelled!?! Oh nooooooooooooo…

  2. Best of luck getting it working again. Looks like a great opportunity to do a repair job…In space.

  3. So, the pump will not find on a Progress or a Falcon 9? How big is it?

    Godspeed, ISS. I have faith this will be resolved.

  4. Oh well it is moves it can brake down! It is not clear though about the cooling loop. Each solar power wing module has its own radiators, four of them. I don’t think they are cross-connected to each other. Are they? There are two main radiator wings by the main structure of ISS. Did one of them stop pumping?

  5. Now everybody needs to keep a cool head!

    I’m confident this will be fixed, eventually. Full failure happened to MIR and was fixed. ISS is better than that, surely, it has the back up and spares.

    Slightly OT:

    Oh well it is moves it can brake down!

    Sadly that applies even to black holes – or universes. (Evaporation, heat death.)

  6. Progress is pretty small (just an unmanned Soyuz). Falcon 9 is a rocket and has only flown once The Dragon capsule (that flys ontop of the Falcon 9, has never flown and even if that holds schedule it will not be until late 2011 before it makes its first trip to ISS. Once again it is only a capsule. Only the shuttle can bring something that large up there. Just another reason to keep the shuttle option alive.

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