Spacewalking astronauts are making urgent repairs at the International Space Station.
Commander Peggy Whitson and Jack Fischer went out this morning, three days after a critical relay box abruptly stopped working. Even though a second unit managed the data load just fine, NASA scrambled to put together a spacewalk in order to restore backup capability.
The system is vital for operating the station's solar panels, radiators and robotic equipment.
The failed data-relay box was just installed in March.