At 9:53 p.m. EST, alarms sounded once again aboard the International Space Station. Flight controllers confirmed they are false alarms. The sequence started with a false rapid depressurization alarm originating from the Poisk mini research module that subsequently tripped false fire alarms in the Columbus laboratory and the Quest airlock.
The crews of Atlantis and the space station were wakened and took steps to respond to the alarms and restore the systems. The shuttle crew turned off the fan in the airlock that connects the shuttle to the station and inserted a lithium hydroxide canister to scrub carbon dioxide. At 10:26 the shuttle crew was given the go-ahead to go back to sleep.
Because it will take about another 90 minutes to return the Quest airlock to the normal configuration, spacewalkers Mike Foreman and Randy Bresnik will abandon the campout protocol and go to sleep elsewhere. They will perform an exercise protocol in the morning to scrub nitrogen from their systems, which the campout protocol normally accomplishes.
Teams in the space station Flight Control Room are discussing how the incident might affect tomorrow morning’s timeline. The wakeup time has moved 30 minutes later, to 3:58 a.m. and to accommodate the new wake up time, the spacewalk will be shortened by 30 minutes, removing some “get ahead” tasks that were planned for the excursion.
At this time, flight controllers do not know why the Poisk module generated another false rapid depressurization alarm.