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ISS NASA Space

Ammonia Leak Alarm On the ISS Forces Evacuation of US Side: Crew Safe 95

Posted by Soulskill from the send-up-a-plumber dept.
New submitter BabelBuilder writes: An alarm signaling a possible ammonia leak aboard the ISS this morning caused the crew to evacuate the U.S. side of the station. All crew aboard the station are safe. "Flight controllers in Mission Control at NASA's Johnson Space Center in Houston saw an increase in pressure in the station's water loop for thermal control system B then later saw a cabin pressure increase that could be indicative of an ammonia leak in the worst case scenario. Acting conservatively to protect for the worst case scenario, the crew was directed to isolate themselves in the Russian segment while the teams are evaluating the situation." They don't yet know whether it was caused by a faulty sensor, a problem in the relay box, or another malfunction.
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Ammonia Leak Alarm On the ISS Forces Evacuation of US Side: Crew Safe More

Ammonia Leak Alarm On the ISS Forces Evacuation of US Side: Crew Safe

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  • This is why I like analog gauges... (Score:4, Interesting)

    by TWX ( 665546 ) on Wednesday January 14, 2015 @12:07PM (#48811489)
    ...with no electrical or electronic component to their basic functionality. I find I can confirm false-readings much more easily than relying on an electronic sensor, and that it seems like at least with automobiles, the sensors themselves fail more often than the conditions that the sensors were designed to detect actually manifest.

    • Re:This is why I like analog gauges... (Score:5, Insightful)

      by Russ1642 ( 1087959 ) on Wednesday January 14, 2015 @12:15PM (#48811577)

      When there are a thousand sensors it gets problematic to monitor all of them. That's why we invented electronic sensors, so that we could use software to do all the work of monitoring them, logging data, triggering alarms, etc.

    • Re:This is why I like analog gauges... (Score:5, Interesting)

      by Kozar_The_Malignant ( 738483 ) on Wednesday January 14, 2015 @12:46PM (#48811833)
      You want analog? Check this out. This is a 360 view of the engineer's station [nmusafvirtualtour.com] of a Convair B36. I'm not quite sure where I'd stash my slide rule, but I'm sure there's a spot somewhere.

      • Re: (Score:2, Informative)

        by Anonymous Coward

        Interesting, thanks. It looks more complicated than it is since everything is repeated 6x for each engine.

        • True, however many of the gauges are selectable for individual cylinders of each engine; head temperature and the others in the left bank of six columns. Power was six Pratt & Whitney R-4360 radials, each with 28 cylinders in four banks of seven. Having an individual cylinder drop out was not uncommon apparently.

        • And 4x for each jet engine!

          • this appears to be one of the earlier ones before the addition of the four jet engines.

            • No it has them, you can see the jet throttles on the left of the cockpit roof (you have to look behind you).

              • Right you are. I missed that. The jets were mostly used for takeoff and for added speed over target. Interesting that the radials have throttle control at both the pilot's and engineer's stations, while the jet throttles are only up front, at least as far as I can tell.

      • There's a bank of switches on the right for each engine, the label is worn down but I'm pretty sure it says "ENGINE OIL DILUTE" 8-(

    • This is why I like analog gauges with no electrical or electronic component to their basic functionality. I find I can confirm false-readings much more easily than relying on an electronic sensor

      Do you also enjoy spending hours that could be used productively doing nothing but working your way through gauges scattered across a system? Because that's one of the hidden costs of analog gauges - either you keep the system simple and keep the gauges near the point of measurement, or make it more complex and heavier by introducing a method to transfer the measured quantity (fluid, gas, what have you) to a convenient location for the gauge? (And an awful lot of what people see as analog gauges are actually voltage or resistance meters - the measured quantity is measured locally and then transmitted to a distant gauge as an analog electrical signal.)
       
      On top of that, you can only confirm false readings if it's not the gauge or measurement system itself supplying the false reading in the first place. Analog gauges do break and their calibration does drift. Piping used to transfer fluid or gas to a measurement point does get clogged up. (And people shut or forget to open gauge stops and isolation valves at the most inconvenient of times.) If it's a hybrid (analog mechanical and analog electrical) system, there's a whole additional level of potential for faults and drifting calibration (without any of the advantages that using the same wiring for digital provides).
       

      it seems like at least with automobiles, the sensors themselves fail more often than the conditions that the sensors were designed to detect actually manifest.

      The plural of anecdote is not data.
       
      In my experience, the vast majority of people who pine for analog gauges have never dealt with an analog system other than their automobile dashboard (which after the late 80's is probably a hybrid (digital with analog displays) system anyhow) or something else equally simple and only having a handful of gauges (at most) in the first place. I have (USN Submarine Service, '81-'91), and I'll take a digital system over an analog system any day of the week. They're much easier to maintain, offer far more functionality, and are much easier to use.

    • Also, it will allow dramatically hopeful crew to tap the gauges as they edge towards criticality...

    • Re: (Score:2)

      by antdude ( 79039 )

      Why not have both analog and digital?

  • Cold War calling... (Score:3)

    by __aaclcg7560 ( 824291 ) on Wednesday January 14, 2015 @12:14PM (#48811565)
    When did the Iron Curtain between Russia and U.S. went up on the International Space Station?


    • When did the Iron Curtain between Russia and U.S. went up on the International Space Station?

      Don't worry, they had to show their papers at the border. We're still safe from external threats - support your local Congressman.

    • Re: (Score:1)

      by Anonymous Coward

      The ISS started life as Mir 2 and Space Station Freedom. When the cold war ended and NASA's and Roscosmos's budgets where slashed, they decided to put their heads (and stations) together and make one station with some of the modules they had been planning for their respective next-generation space stations. Thus, there's the US truss and the Russian truss, with (partly?) independent life-support systems.

      There's a sprinkling of modules from various other countries, but the backbone was all made by the big

    • Well, there's the West ISS and East ISS and all the food has to be airlifted (spacelifted?) there.

  • That's just NASA-speak for "Jim farted" (Score:4, Funny)

    by NotDrWho ( 3543773 ) on Wednesday January 14, 2015 @12:15PM (#48811575)

    Roger, Houston, we have another "ammonia leak."

    Requesting that you please stop sending up the freeze-dried chili in the supply missions, at least while Jim is on station.

    • wouldn't that be Methane? Besides it is a segwayinto the new EPA rules for Oil and Gas producers so Chili will have to be included in the category.

  • Anyone who knows refrigeration? (Score:3)

    by fuzzyfuzzyfungus ( 1223518 ) on Wednesday January 14, 2015 @12:19PM (#48811609) Journal
    I'm a trifle surprised that the ISS would be using ammonia in its refrigeration system. I understand that it is a common terrestrial choice(though mostly in industrial systems, not home use equipment, even if well sealed) because it's pretty good at being a refrigerant and dirt cheap; but it's not a terribly pleasant chemical. Not death on a stick or anything; but an gas that readily dissolves in water to form an alkaline solution potentially strong enough to be a tissue damage risk(good thing that only unimportant stuff like our eyes and lungs are naturally moist, right?).

    Given that anything lofted into orbit automatically costs some thousands of dollars a kilogram, I would have expected a slightly more price-insensitive choice, probably one of the fancier halogenated hydrocarbons, or a mixture of them.

    Does anyone know why ammonia was used instead? Is it that a leak would be dangerous even if the refrigerant were 'the warm fragrance of a spring day'; because of the life-critical nature of the refrigeration system and the relatively tiny volume of breathable atmosphere aboard the station, making using a less noxious refrigerant little more than a way of avoiding alkali burns and asphyxiating or overheating instead? Is ammonia sufficiently superior(per unit mass, volume, or both) that it would be heroically more expensive to ship a different refrigerant into orbit? Some other factor I'm not considering?

    • Re:Anyone who knows refrigeration? (Score:5, Insightful)

      by Russ1642 ( 1087959 ) on Wednesday January 14, 2015 @12:23PM (#48811653)

      If anybody knows about refrigeration it's probably the people that designed the cooling system on the ISS.

      • Re: (Score:2, Informative)

        by Anonymous Coward

        Indeed:

        "Compared to other cooling agents such as heptane, toluol or freon, anhydrous ammonia requires a pumping power that is lower by a factor of 6 to 16, at the same time that the specific heat is four to seven times higher."
        Messerschmid & Bertrand, "Space Stations" p. 201. (ISBN 3-540-65464-X)

      • Re: (Score:2)

        by Trogre ( 513942 )

        Why's that? Are the lowest bidders always the best experts?

        (remove tongue from cheek)

      • If anybody knows about refrigeration it's probably the people that designed the cooling system on the ISS.

        Oh, I didn't mean to imply that I thought they'd screwed up; but my own(quite limited) knowledge of the subject had led me to assume that something other than ammonia would have been used, so I was curious about what it was that I didn't know that made ammonia the choice.

    • Re: (Score:1)

      by jfp51 ( 64421 )
      Probably because they have been working with it for decades and it is a known quantity, instead of having to recertify, retest, remanaufacture cooling systems based on something else. I am not a rocket scientist so this is an educated hunch.

    • Re:Anyone who knows refrigeration? (Score:4, Informative)

      by ColdWetDog ( 752185 ) on Wednesday January 14, 2015 @12:29PM (#48811693) Homepage

      Because ammonia works. It handles wide temperature swings. It is very efficient weight wise. The tech is well known. The instrumentation is well known. The only downside is that it's impressively corrosive. That said, the Russians don't use it [space.com].

      Which, in the end, is likely why we do.

      • That said, the Russians don't use it [space.com].

        Checking out their link, their exterior coolant loop isn't anything hazardous. Interior is 'triol fluid' which is 70% water, 30% glycerin, which is also non-toxic.

      • Re: (Score:2)

        by caseih ( 160668 )

        Except that your diagram shows the US side doesn't use ammonia either for interior cooling; just water. Or am I reading that wrong? Obviously there must be a heat transfer point where the water cooling loop transmits heat into the ammonia cooling loop for external radiation. If that point is inside somewhere, that could be a point of potential leak I suppose.

      • Looking at that link, it looks like the ammonia loop is used for cooling the solar panels, I am surprised it even enters the modules at all, as it could be a closed loop between the solar panels and the radiators (with a pump, which might be the part inside the modules).

    • If it was me designing this (and I have no idea what I'm doing) I would try to use nitrogen, mostly on grounds of it's not very reactive and you have a lot of it around anyway (the ISS mimics earth atmosphere).

    • Re: (Score:1)

      by Anonymous Coward

      Ammonia is used in absorption refrigeration systems. No mechanical compressor; just boiling gases to create the refrigeration effect. They may be heavier and more expensive than compressed-gas refrigeration systems, but they only require a heat source to operate. There are likely multiple ways to get heat piped to the refrigeration units in a space station that don't require much (or any) additional electrical power -- which is probably where the trade-off is.

      • also, it (R717) is the most efficient refrigerant. There is renewed interest for that reason in using it in more traditional applications

    • Only on the US side. The russian modules use CO2, if I remember correctly.

    • Is it that a leak would be dangerous even if the refrigerant were 'the warm fragrance of a spring day'; because of the life-critical nature of the refrigeration system and the relatively tiny volume of breathable atmosphere aboard the station

      I can't speak to the ISS, but one of the downsides of the fancy(ier) refrigerant we used (and still use AFAIK) onboard USN submarines was that it breaks down into carbon monoxide and (IIRC) phosgene gas under rather moderate heat. So, you had a tasteless, odorless gas

      • Christ. Partying like it's 1915 in a tiny, sealed, underwater tube. That's overtly horrifying. I imagine that motivating whoever was responsible for checking for leaks was not that difficult?

    • From one who should know. (Score:5, Informative)

      by DerekLyons ( 302214 ) <fairwater@gmaLISPil.com minus language> on Wednesday January 14, 2015 @05:49PM (#48814425) Homepage

      Does anyone know why ammonia was used instead?

      I emailed a friend who worked on Station's ECLSS back in the 90's, and this was his reply:

      "Ammonia has a great specific heat (ability to carry the thermal load), plus its boiling and freezing points work really well in space applications. It's also (aside from toxicity) a very well-known, simple, cheap and fairly easy material to work with. The way the TCS loops work on ISS, the ammonia loop is external; it never mixes with the internal (water) loops. There are external heat exchangers to pass the thermal loads from inside to outside; the water loops out of the pressure vessels through the end cones to the heat exchangers and back inside. The only way for ammonia to get into the water loop (it seems to me) would be a debris strike or something like that in a heat exchanger (and they're protected by MMOD shielding, as well as being rather out of the way)."

  • Obilg HAL 9000: (Score:3)

    by seven of five ( 578993 ) on Wednesday January 14, 2015 @12:25PM (#48811669)
    "I would recommend that we put the unit back in operation and let it fail."

  • Sorry, Hector spilled the floor cleaner again. He won't let it happen again.

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