The space shuttle Endeavour undocked from the international space station a day early on Sunday, as NASA kept a wary eye on Hurricane Dean.
Space agency managers worried that the storm would move toward Houston and force them to evacuate to a smaller-staffed makeshift control center at Kennedy Space Center in Florida. The Endeavour crew prepared to land on Tuesday as a precaution.
"Endeavour departed," space station commander Fyodor Yurchikhin said as ringing bells heralded the shuttle's parting, a tradition borrowed from the Navy.
"Thanks for everything, Scott and Endeavour crew," station resident Clay Anderson said to shuttle commander Scott Kelly. "Godspeed."
"We couldn't have gotten everything accomplished without you guys," Kelly replied. "We look forward to seeing you back on planet Earth."
The shuttle crew, which includes teacher-astronaut Barbara Morgan, had been at the orbiting outpost since Aug. 10. In that time, they attached a new truss segment to the station, delivered cargo and replaced a failed gyroscope, which controls the station's orientation.
They have had to compress their schedule to get ready for the early undocking. Morgan, who was Christa McAuliffe's backup on the tragic 1986 Challenger mission, was scheduled to talk to students in Massachusetts on Sunday, but that chat was canceled.
A spacewalk on Saturday was shortened so the astronauts could wrap up their work at the station. During that jaunt, the spacewalkers saw the eye of the enormous hurricane swirling in the Caribbean and expressed their amazement at the sight.
The astronauts also skipped flying around the station after undocking to take pictures of the complex, an exercise NASA likes crews to do if the schedule and fuel supply permit.
One thing that remained in their schedule was a close-up laser survey of Endeavour's wings and nose cap, to check for any possible micrometeoroid damage. The astronauts pulled out the shuttle's 100-foot (30-meter) robotic arm and extension boom and began inspecting their ship a few hours after undocking.
Although it was uncertain whether Dean, a Category 4 storm, might strike the Texas coastline later this week, NASA managers said it would be irresponsible not to cut the mission short, especially since most of the tasks had been completed.
"I would defy just about anybody to tell me at this point that there's zero or even extremely low probability or possibility that the storm is going to come here," said launch integration manager LeRoy Cain.
NASA is ready to rush a skeleton crew of flight controllers to Florida, but only if the shuttle cannot land Tuesday for some reason and the hurricane is bearing down on Houston and threatening the city for several days, Cain said.
"That's a fairly, I hope, unlikely scenario simply because all those things have to line up," he said.
In 26 years of space shuttle flight, NASA never has had to call up an emergency Mission Control, although it has been practiced.
NASA's hurricane deliberations followed a decision to forgo shuttle repairs.
Mission managers concluded earlier this week that a deep gouge on Endeavour's belly posed no Columbia-like threat to the seven crew members during re-entry and also would not lead to lengthy postflight shuttle repairs.
For several days, managers had considered sending two astronauts out with black protective paint and untested goo to patch the 3.5-inch-long, 2-inch-wide (9-by-5-centimeter) gouge that dug all the way through the thermal tiles.
The gouge was caused by debris that broke off a bracket on Endeavour's external fuel tank during liftoff Aug. 8. Engineers still do not know whether it was foam insulation, ice or a combination of both. In any case, NASA said it will not launch another shuttle until the longtime troublesome brackets are fixed.