At 12:20 p.m. CDT, using a scoop tool as a hammer, Doug Wheelock successfully hammered open the previously stuck M3 line, enabling its demate from the pump module that he and Tracy Caldwell Dyson have been working to replace.
Before unlatching the line however, Wheelock and Caldwell Dyson encountered a steady stream of ammonia emanating from the valve, effectively creating a storm of frozen-ammonia snowflakes enveloping the spacewalkers' workspace.
As a result, flight controllers directed the astronauts to secure the line in place and reinstall a spool positioning device in an effort to halt the leak.
Approaching seven hours and the end of this spacewalk, the release of the final quick-disconnect line, as well as electrical connectors, will be deferred to the next excursion, planned now for Wednesday. Both tasks need to be completed before the failed pump module can be removed, which had been the primary goal for today.