Spacewalking astronauts tackle urgent station repairs

Spacewalking astronauts are making urgent repairs at the International Space Station.Commander Peggy Whitson and Jack Fischer went out Tuesday 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 M