Endeavour Undocks from ISS, Heads Home

The Space Shuttle Endeavour successfully undocked from the International Space Station July 28 and began the trek back to Earth. During the 11-day stay at the ISS, the seven-person Endeavour crew combined with the six-person permanent ISS crew to complete a major build-out at the station over five spacewalks.

Endeavour undocked from the ISS at 1:26 p.m. (EDT), slowly backed away from the station and conducted a victory lap around the station before hitting the thrusters to head for a scheduled July 31 landing at the Kennedy Space Center. The mission is the second longest in shuttle history and the combined crews marked the largest number of people operating in space at the same time. Endeavour crew member Tim Kopra stayed behind to take over as ISS flight engineer while Japan Aerospace Exploration Agency astronaut Koichi Wakata departed in the Endeavour after four months on the station.

"It has been a spectacular and successful docked phase, but all good things must come to an end," Mission Control radioed Endeavour's crew in a morning message.

Over the course of the mission, the crew unloaded and installed Japan's Kibo outdoor laboratory, a literal "front porch" for the ISS allowing for space-exposed science experiments. The Endeavour blasted off from Cape Canaveral July 15 after stormy Florida weather forced NASA to postpone launches on July 11, 12 and 13. In June, NASA twice scratched the mission due to a launch pad hydrogen gas leak that has since been fixed.

Beyond the repeated launch delays, the 16-day mission was not without its tense moments, from concerns about multiple debris hits, likely from pieces of foam flaking off Endeavour's external fuel tank during the initial minutes of the launch from Cape Canaveral, to a balky toilet to higher-than-normal carbon dioxide levels in Mission Specialist Chris Cassidy's spacesuit during a spacewalk.

"We've had our challenges," Holly Ridings, lead space station flight director for the mission, said July 28. "We've all worked together to overcome those challenges and complete what looks like a very, very nominal ... mission, almost exactly like we planned it."

After studying video of the launch, NASA determined that Endeavour suffered "some debris incidents" less than 2 minutes after the launch. After Endeavour maneuvered the ship over the ISS before docking on July 17 so that the ISS crew could check for possible damage, NASA said there was no serious damage from liftoff debris.

Heat shield damage has been a particular concern for NASA since the Space Shuttle Columbia disintegrated returning to Earth after a 2003 mission, killing all seven astronauts aboard. The cause of the disaster was later traced to a chunk of foam off the external fuel tank striking the Columbia's left wing 82 seconds after blastoff.