Window 2 on the Cupola module has been hit by a minor MicroMeteoroid and Orbital Debris (MMOD) strike. With the window\u2019s protective shutter closed, per flight rules, ISS managers are evaluating photos of the damage \u2013 downlinked from the International Space Station (ISS) \u2013 before they are expected to give the crew clearance to reopen the shutter.<\/p>\n
Cupola Window:<\/p>\n
After arriving at the ISS with Node 3, during Endeavour\u2019s STS-130 mission, the European Space Agency (ESA) built Cupola has provided Station crews with a stunning view of the planet, often shared with the public via downlinked photography.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/06\/Z35.jpg\" "\\"Z3\\"")
The module also hosts a Robotic Work Station (RWS), allowing crewmembers to actually see Visiting Vehicles (VVs) \u2013 such as SpaceX\u2019s Dragon and Japan\u2019s HTV \u2013 arrive for berthing, complimenting the camera views of their displays, allowing for increased situational awareness when operating the Station\u2019s robotic assets.<\/p>\n
The Cupola\u2019s seven windows were exposed to space for the first time during STS-130\u2019s EVA-3, following the removal of the module\u2019s MLI blanket insulation by spacewalkers Bob Behnken and Nick Patrick.<\/p>\n
After the spacewalkers removed the launch locks on the windows, the ISS crew cycled the window shields\/shutters one at a time, providing them with the first view of the Earth from their new observation deck.<\/p>\n
All of the windows weren\u2019t open at the same time, with the task simply used to check the shutters opened without a problem. A few hours later, all of the windows were opened together, an event that is now commonplace on the ISS.<\/p>\n
The module has hardly suffered from any issues during its tour of duty with the orbital outpost, with only a minor temperature issue noted ahead of Dragon\u2019s arrival last month.<\/p>\n
Technology News (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n Through no fault of its own, the MMOD strike is a risk all spacecraft have to deal with, although exposed windows are built to withstand such impacts.<\/p>\n \u201cCupola Window MMOD Strike \u2013 On June 10, the crew reported an MMOD strike on Cupola window 2 and downlinked photos (full set available on L2) of it,\u201d noted L2 level ISS Status (LINK). \u201cThe shutter for window 2 is closed now, as required by flight rules, until the MMOD strike has been evaluated. <\/p>\n \u201cTeams are working to determine the structural implications of the MMOD strike and clear the window 2 shutter for re-opening if possible.\u201d<\/p>\n The flight rules are naturally cautious, in order to ensure a large amount of margin for crew safety. It is highly likely this will be cleared as an issue after the evaluations are completed.<\/p>\n Recent ISS Articles: http:\/\/www.nasaspaceflight.com\/tag\/iss\/<\/p>\n It is understood that this MMOD srike is the first to be suffered by a Cupola window.<\/p>\n The window is made up of four panes \u2013 an inner scratch pane to protect the pressure pane from accidental damage, two pressure panes 25mm thick to maintain cabin pressure, and finally an outer debris pane. The debris panes can be replaced individually, via EVAs. <\/p>\n MMOD:<\/p>\n Strikes of these tiny pieces of debris are relatively commonplace and are only immediately noticeable when they impact on areas such as windows.<\/p>\n Recent MMOD related articles: http:\/\/www.nasaspaceflight.com\/tag\/mmod\/<\/p>\n Such strikes were observed on a large amount of Space Shuttle missions, especially late into the mission when the orbiter had undocked from the protection of the ISS and was preparing to head home. However, they are taken seriously, given they are the third biggest threat to losing a vehicle during a mission \u2013 second only to launch and re-entry.<\/p>\n This mission held the largest risk to the orbiter, given it was the only post Return To Flight mission that did not have the \u201csafe haven\u201d option of docking with the ISS, ahead of a rescue orbiter being flown to pick up the crew.<\/p>\n STS-125 would also see an increase in the concentration of MMOD, due to the region of Low Earth Orbit (LEO) Atlantis flew in for the majority of her mission.<\/p>\n The Program Requirements Control Board (PRCB) results \u2013 which took into account satellite breakups and a variety of other components evaluated to be in Atlantis\u2019 orbital neighborhood \u2013 showed that the overall risk of a Loss Of Crew and Vehicle (LOC\/V) scenario due to MMOD impact(s) to the Thermal Protect System (TPS) was 1 in 185, with an error factor of 1.35 based on MMOD distribution, velocity, and density uncertainties.<\/p>\n As noted, most of the risk was associated with impacts on the TPS, as opposed to the windows. In the end, Atlantis completed her mission successfully and without any MMOD related concerns.<\/p>\n \u201cMMOD Window 6 Impact \u2013 crew reported 0.5\u201d diameter to the PLT right window to the thermal pane, 1\/32\u201d depth,\u201d noted the MER report. \u201cBased on analysis the window should have no issues for peak heating M=8.0, but could form cracks but remain intact during peak loading M=0.7. Pilot visibility should not be hindered by this location if it cracks.<\/p>\n \u201cNo concern for orbit thermal cycles. Dynamic loading on the pane takes into account for the window frame thermal response.\u201d<\/p>\n Meeting notes showed Mr Cain asked if there was a need to mitigate heat loads on the window \u2013 had it been determined that could have been a problem during entry \u2013 with his team reporting back that the thermal pane of the window would be able to handle peak heating.<\/p>\n Clarifying the impact showed no signs of risking a LOV\/C during re-entry, it was noted that only a hole through more than just the thermal plane of the window would raise concerns \u201cwe might have to not come home,\u201d which would have resulted in calling Discovery to provide a LON (Launch On Need) rescue.<\/p>\n Endeavour landed safely with no propagation of the MMOD damage during her reentry.<\/p>\n An example of the risk was seen during STS-109, when a small piece of debris was lodged in Columbia\u2019s coolant loop 2 and restricted the flow of Freon-22 in that coolant loop. The amount of Freon-22 in the coolant loop was slightly below the flight rule red-limit, but after exhaustive analysis by the engineers on the ground, they decided to press on with the mission.<\/p>\n Usually spotted during post flight processing, Endeavour\u2019s radiator damage showed as a \u201cbullet hole\u201d on her left hand aft radiator number 4. Engineers repaired the area during her Orbiter Processing Facility (OPF) flow.<\/p>\n Atlantis\u2019 damage during STS-115 was the second largest debris strike in Shuttle history, causing a .108 inch diameter hole at entry point, with one-half of an inch thick damage to the honeycomb structure.<\/p>\n Interestingly, United Space Alliance (USA) engineers discovered a piece of circuit board embedded into the radiator panel during repairs, showing the MMOD strike originated from a piece of another vehicle, likely an Upper Stage from an expendable vehicle or a satellite.<\/p>\n (Images: L2 Content (all MMOD content), and NASA)<\/p>\n (NSF and L2 are providing full transition level coverage, available no where else on the internet, from Orion and SLS to ISS and COTS\/CRS\/CCDEV, to European and Russian vehicles). <\/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)<\/p>\n","protected":false},"excerpt":{"rendered":" Window 2 on the Cupola module has been hit by a minor MicroMeteoroid and Orbital Debris (MMOD) strike. With the window\u2019s protective shutter closed, per flight rules, ISS managers are evaluating photos of the damage \u2013 downlinked from the International Space Station (ISS) \u2013 before they are expected to give the crew clearance to reopen […]<\/p>\n","protected":false},"author":1,"featured_media":30330,"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":[9005,233,8970],"class_list":["post-40093","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-cupola","tag-iss","tag-mmod"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40093"}],"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=40093"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/40093\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/30330"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=40093"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=40093"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=40093"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/06\/Z341.jpg\" "\\"Z34\\"")
This latest strike, to Window 2 on the Cupola, looks more dramatic via close up photos, but is in reality very small and probably would not have been instantly obvious to crewmembers entering the module.<\/p>\n![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/06\/Z74.jpg\" "\\"Z74\\"")
In the event of the damage being more serious, on-orbit replacement of an entire window is a design feature. Such a replacement would require an EVA to fit an external pressure cover to allow for the changeout, with a pressure cover requiring a flight up to the ISS.<\/p>\n![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/06\/A61.jpg\" "\\"A61\\"")
Extensive evaluations took place ahead of each shuttle mission, not least Atlantis\u2019 STS-125 flight into space, a mission that provided one final servicing mission to the Hubble Space Telescope.<\/p>\n![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/06\/Z351.jpg\" "\\"Z35\\"")
Examples of Mission Management Team (MMT) evaluations into window damage during a mission can be seen via STS-126\u2019s flight, where then MMT Chair LeRoy Cain discussed the Mission Evaluation Room (MER) report into an impact on Endeavour\u2019s Window 6 (Pilot Window).<\/p>\n![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2012\/06\/Z36.jpg\" "\\"Z36\\"")
Both Endeavour and Atlantis would also receive a flesh wound from MMOD strikes to their radiator panels, a danger in its own rights, given the potential of an impact to one of the Freon-22 coolant plumbing inside the radiator panel. Such an impact could cause an entire coolant loop to be shut down and be declared as \u2018failed\u2019. This would have forced an immediate landing on the earliest US landing opportunity.<\/p>\n