Editing Space Shuttle Atlantis (section)

==Problems==

===Composite overwrapped pressure vessels===
NASA announced in 2007 that 24 helium and nitrogen gas tanks in ''Atlantis'' were older than their designed lifetime. These [[composite overwrapped pressure vessel]]s (COPV) were designed for a 10-year life and later cleared for an additional 10 years; they exceeded this life in 2005. NASA said it could not guarantee any longer that the vessels on ''Atlantis'' would not burst or explode under full [[pressure]]. Failure of these tanks could have damaged parts of the orbiter and even wound or kill ground personnel. An in-flight failure of a pressure vessel could have even resulted in the loss of the orbiter and its crew. NASA analyses originally assumed that the vessels would [[Pressure vessel#Leak before burst|leak before they burst]], but new tests showed that they could in fact burst before leaking.

Because the original vendor was no longer in business, and a new manufacturer could not be qualified before 2010, when the shuttles were scheduled to be retired, NASA decided to continue operations with the existing tanks. Therefore, to reduce the risk of failure and the cumulative effects of load, the vessels were maintained at 80 percent of the operating pressure as late in the launch countdown as possible, and the launch pad was cleared of all but essential personnel when pressure was increased to 100 percent. The new launch procedure was employed during some of the remaining launches of ''Atlantis'',<ref name="aging">{{Cite web|url=http://www.space.com/news/ft_070604_aging_orbiters.html|title=Orbiters Feel Pains of Aging |access-date=November 6, 2007|publisher=Space.com|year=2007|first1=Todd|last1=Halvorson|first2=John|last2=Kelly|work=[[Florida Today]]}}</ref> but was resolved when the two COPVs deemed to have the highest risk of failure were replaced.<ref name="copv">{{Cite web|url=http://www.nasaspaceflight.com/2010/07/nasa-reviews-copv-for-final-program-flights/|title=NASA Reviews COPV Reliability Concerns for Final Program Flights|access-date=July 19, 2010|website=NASASpaceflight.com|first=Chris|last=Gebhardt|date=July 18, 2010}}</ref>

===Window damage===
After the STS-125 mission, a work light knob was discovered jammed in the space between one of ''Atlantis''{{'}}s front interior windows and the Orbiter dashboard structure. The knob was believed to have entered the space during flight, when the pressurized Orbiter was expanded to its maximum size. Then, once back on Earth, the Orbiter contracted, jamming the knob in place. Leaving "as-is" was considered unsafe for flight, and some options for removal (including window replacement) would have included a 6-month delay of ''Atlantis''{{'}}s next mission (planned to be [[STS-129]]). Had the removal of the knob been unsuccessful, the worst-case scenario was that ''Atlantis'' could have been retired from the fleet, leaving ''Discovery'' and ''Endeavour'' to complete the manifest alone. On June 29, 2009, ''Atlantis'' was pressurized to {{convert|17|psi|lk=in|abbr=on}} (3 psi above ambient), which forced the Orbiter to expand slightly. The knob was then frozen with [[dry ice]], and successfully removed.<ref name="knobremoval">{{Cite web|url=http://www.nasaspaceflight.com/2009/06/atlantis-window-pane-begins-longerons-damaged-accident/|title=Knob removed, Atlantis window inspection begins – longerons in cart accident|access-date=June 30, 2009|publisher=NASASpaceflight.com|year=2009|first=Chris|last=Bergin}}</ref> Small areas of damage to the window were discovered where the edges of the knob had been embedded into the pane.<ref name="knob">{{Cite web|url=http://www.nasaspaceflight.com/2009/06/window-damage-on-atlantis-threatens-six-month-delay-to-sts-129/|title=Window damage on Atlantis threatens six-month delay to STS-129|access-date=June 25, 2009|publisher=NASASpaceflight.com|year=2009|first=Chris|last=Bergin}}</ref> Subsequent investigation of the window damage discovered a maximum defect depth of approximately {{convert|0.0003|in|μm|abbr=on|lk=out}}, less than the reportable depth threshold of {{convert|0.0015|in|μm|abbr=on|lk=out}} and not serious enough to warrant the pane's replacement.<ref name="windowok">{{Cite web|url=http://www.nasaspaceflight.com/2009/07/endeavour-into-countdown-atlantis-window-damage-cleared/|title=Endeavour heads into countdown – Atlantis window damage cleared|access-date=July 31, 2009|publisher=NASASpaceflight.com|year=2009|first=Chris|last=Bergin}}</ref>