Forecasters said the odds of good weather for Monday's scheduled liftoff of Endeavor are at 70 percent- the main concerns are stiff crosswind and low clouds. The launch that was scheduled last month was scrubbed because of an electrical problem.
Commander Mark Kelly and his five crewmates returned to Kennedy Space Center on Thursday. Their families will follow this weekend, including Kelly's wife, Arizona Rep. Gabrielle Giffords, who was critically wounded in January at a political event in Tucson.
A crowd of 500,000 is anticipated for Monday's launch. This will be the 25th and final journey for Endeavour. Four spacewalks are planned during the 16-day mission.
Only one other shuttle flight remains, by Atlantis in July.
The Associated Press contributed to this story