Launch from Cape Canaveral (KSC); landing at Cape Canaveral (KSC); ISS-20-12A.1 SH-LSM ITS-P5; mission Celsius.

Liftoff was originally scheduled for December 07, 2006, but that attempt was canceled due to a low cloud ceiling.

The main goals of the mission were delivery and attachment of the International Space Station's P5 truss segment, a major rewiring of the station's power system.

Docking to ISS and common work with the ISS expedition 14; transfer Williams to ISS and Reiter to the crew of STS-116.

First EVA by Curbeam and Fuglesang on 12.12.2006 (6h 36m) to align and connect the P5 truss segment to P4. They also replaced a faulty video camera attached to the S1 truss. Since they worked ahead of the time-line, the two astronauts were also able to complete some get-ahead tasks.

On December 13, 2006, the crew attempted retraction of the P6 port-side solar array. Problems with the array folding due to 'kinks' and 'billows' led the controllers to redeploy the array (from about 40% retracted). There then followed a series of more than 40 commands to furl and unfurl the arrays in an effort to get them properly aligned and folded. The retraction efforts were abandoned for the day.

Second EVA by Curbeam and Fuglesang on 14.12.2006 (5h 00m) to reconfigure power on channels 2 and 3 of the station's electrical system.

Third EVA by Curbeam and Williams on 16.12.2006 (7h 31m) to reconfigure power on channels 1 and 4 of the station's electrical system. As an "add-on task" to the EVA, astronauts Curbeam and Williams also continued work on the retraction of a sticking solar array, enabling the retraction of another six sections of the P6 array. At the end of the EVA there were another 11 "bays", or 35% left to retract.

Fourth and unplanned EVA by Curbeam and Fuglesang on 18.12.2006 (6h 38m) to fully retract the array.

The first landing opportunity at Kennedy Space Center was abandoned due to unfavorable weather conditions.

Williams landed on 22.06.2007 at 19:49 UTC with STS-117.