NASA Administrator Charles Bolden speaks during a news conference in Berlin on Monday. Bolden said no single country was indispensable to the International Space Station's success. Michael Sohn/AP hide caption

itoggle caption Michael Sohn/AP

From left: U.S. astronaut Steve Swanson, and Russian cosmonauts Alexander Skvortsov and Oleg Artemyev prior to the launch of their Soyuz-FG rocket Wednesday at the Baikonur Cosmodrome in Kazakhstan. Dmitry Lovetsky/AP hide caption

itoggle caption Dmitry Lovetsky/AP

NASA astronaut Chris Cassidy performs a spacewalk in May to inspect and replace a pump controller box on the International Space Station. On Saturday, two astronauts will perform the first in a series of similar spacewalks to fix a broken cooling line on the ISS. AP hide caption

itoggle caption AP