Final confirmation of the two-day extension is pending Russian concurrence of NASA's request for a one-day delay to their Soyuz launch, currently scheduled for Saturday. That would allow Endeavour to remain docked to the Station until at least Monday to help resolve the computer problems which were first noticed Tuesday night. The Soyuz vehicle was rolled out to its launch pad at the Baikonur Cosmodrome in Kazakhstan at dawn today.
With one of three command and control computers still up and running on board the station, flight controllers worked through the day to overcome what is believed to be a software problem with the other two command computers and their processing systems. Ultimately a decision was made to postpone the unberthing of the Raffaello logistics module from the Unity module until Friday while ground controllers worked to recover the computers. With other work on hold, the crewmembers completed packing up Raffaello with unneeded gear and trash, which will be brought back to Earth.
If at least one additional command computer can be recovered overnight, and engineers can reboot two fault protection computers in the Unity module which also shut down earlier today, the Raffaello module could be unberthed around midday Friday. Procedures to bring at least one additional computer back on line for further operations are expected to take about 10 hours.
If Raffaello can be returned to Endeavour's cargo bay tomorrow, then the crew will likely be given the green light to press ahead with the handoff of a pallet from the newly installed Canadarm2 Station robot arm to Endeavour's slightly smaller robot arm on Saturday, setting the stage for undocking on Monday.
To recover the two Unity computers, which offer a defense against other computer malfunctions by automatically rebooting them, controllers will have to perform a complex resynchronization procedure early Friday shortly before the planned wakeup of the two crews.
Endeavour has enough power and other consumables to remain in orbit until Friday, if necessary. With a two-day mission extension, landing would occur on Wednesday.
The crews of Endeavour and the International Space Station are scheduled to be awakened around 2:40 a.m. Central time Friday. Meanwhile, all of Endeavour's systems continue to function flawlessly as it orbits the Earth linked to the ISS.