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The system is designed to collect heat from the Internal Thermal Control Systems in the US Lab, Node-2, COL, JEM, and Node-3, via IFHXs (Interface Heat Exchanger). The PM provides the motive force to transport the ammonia around the loop.<\/p>\n
The opening EVA was delayed twice, as engineers on the ground worked through refining the EVA timeline, while training runs were carried out inside the NBL (Neutral Buoyancy Laboratory) at the Johnson Space Center (JSC).<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/08\/A35.jpg\" "\\"A3\\"")
The EVA-1 tasks will run in the following order: \u201cDemate connections and QDs (quick disconnects) on the old PM (Pump Module); Install PM jumper to bypass PM and connect ATA (Ammonia Tank Assembly) at S1 to Loop-A; Install AGB (Adjustable Grapple Bar), currently on ESP-2 (External Stowage Platform 2), on old PM.<\/p>\n\u201cRemove old PM from S1 (starboard) truss and stow on POA (Payload ORU Accommodation) on the MT (Mobile Transporter) at WS2 (Worksite 2); Prepare spare PM (on ESP-2) for installation, and; Install spare PM on S1 and make electrical & data connections.\u201d<\/p>\n
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Several leaks of ammonia \u2013 seen as snowflakes \u2013 were observed during the demating of QDs on the PM, half way through the EVA\u2019s duration. However, the main issue was with one of the QDs that refused to demate.<\/p>\n
With two alternative QDs demated with no issues, Wheelock returned to M3, which eventually released as planned \u2013 much to the pleasure of ground controllers, who burst out into applause. However, time was running out, leading to the removal of the PM being moved to EVA-2.<\/p>\n
A larger leak of ammonia was then observed during M3\u2019s demating, as the spacewalkers appeared to be working in a snowstorm, as the fluid leaked as flakes. Although no serious contamination was found during suit inspections, a 30 minute bake out inside the airlock ensured none of the hazardous material could return inside of the Station with the suits.<\/p>\n
Ahead of Saturday\u2019s spacewalk, the last US Stage EVA on the ISS was conducted in January, 2008.<\/p>\n
Refer to the live thread for further details, and a review of the live play-by-play text and image coverage.<\/p>\n
A Week Of Planning:<\/p>\n
A large part of the evaluations have related to the Failure Investigation Team (FIT) efforts to overview what is known as the Next Failure Response \u2013 part of a week of extensive evaluations into supporting both the ISS and the EVAs.<\/p>\n
\u201cFIT for failure response actions dealt mainly with items related to supporting EVA with the next worst case failures that take down the 2nd cooling loop,\u201d noted one a several expansive memos and overviews on the evaluations (L2).<\/p>\n
\u201cActions that were noted for the crew include completing the EVA battery charging as soon as possible, looking for the adapter for the US LiOH cartridges for use on the Russian side, and when approval is gained from ISS Program management to request the crew to begin assembling materials to build a second contingency jumper via pin kits with the OGS jumper.<\/p>\n
\u201cThe crew will need to be timelined appropriately to allow the associated hardware to be located for this spare jumper preconfiguration effort. Most of the discussion dealt with how to get the USOS configured to best support comm during an EVA since the Internal Audio Controller (IAC) required for UHF comm to the EV crew has a very short time to overheat (less than 30 minutes) that would result in the termination of the EVA.<\/p>\n
\u201cA scenario was discussed to recover cooling for an MBSU (Main Bus Switching Unit) failure but installation of power jumpers by the crew and thermal cooling reintegration would take approximately 1.5 hours. Improving air cooling via ducts, removing closeouts, and rotating racks was discussed where applicable to gain more thermal clock time.\u201d<\/p>\n
A long list of actions included work to determine the best configuration for removing closeout panels and rotating racks to ensure the best cooling capability in the modules, and bringing the spacewalkers safely back into the airlock \u2013 in the event of another failure before, during and after the opening EVA \u2013 full list on L2.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/08\/A45.jpg\" "\\"A4\\"")
Other planning was dedicated to the EVA task, such as a pump module ammonia vent plan.<\/p>\n\u201cThe team had originally developed a pump module ammonia vent plan that could be completed using ground commanding of various isolation and vent valves in the ETCS,\u201d added another overview.<\/p>\n
\u201cDue to the length of the tasks the crew would be required to perform during a single eclipse pass, coupled with a highly detailed choreography between the EV crew and ground to support this task there is no way to fit the necessary QD manipulations and Pump Module venting within a single eclipse period. <\/p>\n
\u201cThe team decided to proceed with the manual vent option which has no eclipse constraints but does require the crew to position and use the EVA vent tool. In support of this the nominal EVA 1 timeline will, in accordance with the Flight Rules, protect for 2 hours and 20 minutes of consumables at the end of the EVA for EMU decontamination protocols.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2010\/08\/A54.jpg\" "\\"A5\\"")
\u201cIn addition, an action was opened to analyse the requirement to vent the failed pump module during EVA1 or whether it can remain with NH3 in it until EVA 2.<\/p>\nPending the results of this analysis, it may not be required to vent the PM during EVA 1 as long as the NH3 in the pump will not freeze and potentially prevent post failure analysis from determining what caused the original pump failure.\u201d<\/p>\n
A third EVA was being discussed on some memos during the week (L2), relating to an issue on a Remote Power Control Module (RPCM), which \u2013 it was feared \u2013 may have suffered from wiring damaged. By late this week, a third EVA to changeout the RPCM had become \u201cless likely\u201d.<\/p>\n
A full overview of the status of the RPCM will be provided in the EVA-2 article.<\/p>\n","protected":false},"excerpt":{"rendered":"
NASA\u2019s Doug Wheelock and Tracy Caldwell Dyson have completed their eventful opening EVA to changeout a failed ammonia coolant Pump Module (PM) on the International Space Station\u2019s (ISS) External Thermal Control System (ETCS) \u201cLoop A\u201d. Lasting eight hours and three minutes, the spacewalk will be followed by a second EVA next Wednesday. EVA-1: The main […]<\/p>\n","protected":false},"author":1,"featured_media":29523,"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":[567,233],"class_list":["post-40695","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-eva","tag-iss"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40695"}],"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=40695"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40695\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/29523"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=40695"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=40695"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=40695"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}