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Alarms on the ISS are not uncommon and are almost always caused by false sensor readings.<\/p>\n
However, the data on the ground and resulting alarm on the ISS pointed to an ammonia leak \u2013 one of the major risks to a crew on the ISS \u2013 resulting in contingency procedures being implemented. This is a conservative procedure, implemented to completely mitigate even the slightly risk to the onboard crew.<\/p>\n
A major issue would result in the crew evacuating to the two docked Soyuz spacecraft, allowing them to return to Earth.<\/p>\n
Wednesday\u2019s contingency involved the three crew members of the US segment donning protecting masks and evacuating to the Russian segment of the Station \u2013 sealing off the two segments at a hatch point \u2013 while controllers on the ground began a staged shutdown of some systems in Node 2.<\/p>\n
![\"2015-01-14](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2015\/01\/2015-01-14-13_07_46-NASA-Public-350x211.jpg\")
The three crew members currently camped out in the Russian section are Commander Barry Wilmore and flight engineers Terry Virts and Samantha Cristoforetti.<\/p>\nSpaceflight news subscription
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\u201cStation, Houston on one for Butch (astronaut Barry Wilmore) with big picture,\u201d noted CAPCOM Jim Kelly in Houston. \u201cWe\u2019re still working on what happened.<\/p>\n
\u201cWe\u2019re not entirely convinced this is an ammonia leak. It may be that this is a combination of sensor problems, MDM (relays) and thermal effects all throw together in the exact wrong way to look like it was your classic ammonia leak.\u201d<\/p>\n
Ammonia is required on the Station in order to provide cooling to the segments and their array of equipment. <\/p>\n
![\"2015-01-14](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2015\/01\/2015-01-14-14_22_42-IFHX-FRAT-Briefing-Final.pdf-Foxit-Reader-350x242.jpg\")
L2 documentation notes that ammonia can enter the ISS via what is called an Interface Heat Exchanger (IFHX) \u2013 this is a piece of hardware that transfers the heat from the internal LTL (Low Temperature Loop) or MTL (Moderate Temperature Loop) water coolant loops, to the external ammonia coolant loops.<\/p>\nThere are 10 IFHXs on the ISS in total \u2013 two on the US Lab, six on Node 2, and two on Node 3.<\/p>\n
They are located outside the pressure vessel on the endcones of their respective modules.<\/p>\n
![\"2015-01-14](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2015\/01\/2015-01-14-14_24_15-IFHX-FRAT-Briefing-Final.pdf-Foxit-Reader-350x187.jpg\")
It is possible for ammonia to enter the ISS via the IFHX since both the external ammonia loop and the internal water loop are connected to the heat exchanger \u2013 so if the exchanger fails, ammonia can flow from outside to inside.<\/p>\nIn this case, however, it seems the concern is with one of the Node 2 IFHXs that transfers heat from the internal LTL to the external coolant loop B.<\/p>\n
IFHXs can be removed and replaced via EVA if completely necessary.<\/p>\n
However, all indications point to a healthy system, with data evaluated on the ground by engineers in the ISS Flight Control Room in MCC Houston.<\/p>\n
![\"2015-01-14](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2015\/01\/2015-01-14-13_15_53-NASA-Public-350x194.jpg\")
\u201cHey Butch, good news,\u201d was the call from CAPCOM Jim Kelly later in the morning. \u201cEverything is looking normal and we have almost complete insight back. Everything is looking pretty normal right now.<\/p>\n\u201cIt\u2019s becoming a stronger case that this was a false indication, which is great news. We\u2019re going to continue down that path and working to make sure that this was a false indication and work on getting you guys back into the other side (US Segment).\u201d<\/p>\n
Controllers noted their confidence in the health of the USOC section, allowing for the crew members to return at around 8 pm UTC. However, due to the loss of TCS Loop B, they will need to conduct a camp out in the aft of Node 2.<\/p>\n
\u201cSafety of the crew has been achieved through the coordinated and timely actions themselves cosmonauts and astronauts, as well as operational management groups in Moscow and Houston,\u201d added Maxim Matyushin from MCC-Moscow.<\/p>\n
No major operations have been hampered by the contingency, with one main task \u2013 the unloading of the supplies that arrived on the SpaceX CRS-5 Dragon \u2013 already ahead of schedule by the time the alarms sounded.<\/p>\n
(Images: L2\u2019s ISS Section and NASA)<\/p>\n
(L2 Members refer to the L2 ISS Section for Updates, Images and Presentations relating to this situation on the ISS).<\/p>\n
(Click here: http:\/\/www.nasaspaceflight.com\/l2\/ \u2013 to view how you can access the best space flight content on the entire internet and support this site)<\/p>\n","protected":false},"excerpt":{"rendered":"
Alarms in the US section of the International Space Station \u2013 pointing to a potential, but likely false indication of an ammonia leak \u2013 resulted in the two Americans and one European astronaut evacuating into the Russian section of the orbital outpost. It is currently believed bad sensor data \u2013 as opposed to an actual […]<\/p>\n","protected":false},"author":1,"featured_media":30140,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[233],"class_list":["post-39419","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-iss"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/39419"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=39419"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/39419\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/30140"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=39419"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=39419"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=39419"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}