ISS Airlock module.
Early Friday astronauts on board the ISS completed the first spacewalk of the mission, replacing a couple of experiments and performing maintenance. On Saturday, astronauts made a closer inspection of possible damage to the heat tiles underneath the shuttle Endeavour. Ground experts will examine the new pictures.
STS134 crew (dark blue) and ISS Expedition 27 crew.
Both crews gathered together for a space first: Pope Benedict XVI called the crews on a special call to praise them for their hard work and important missions performed on behalf of the people of Earth.
The next spacewalk is scheduled for Sunday.