President Barack Obama says he is extraordinarily proud of the astronauts aboard the linked space shuttle-space station complex.
During a video conference call on Tuesday, Obama questioned the 10 astronauts about everything from how fast they are traveling and exercise in space to what they do besides work on experiments and how weightlessness affects their sleep.
Pupils from Washington-area middle schools and members of Congress joined him for the call.
The crew will spend Tuesday recuperating from Monday's third and final spacewalk of the Discovery shuttle's mission. The hatches between Discovery and the international space station will be sealed Wednesday.
The shuttle will undock and head for home, to land Saturday. - Sapa-AP