Astronauts take spacewalk to find ammonia leak

2 astronauts are spacewalking outside the International Space Station (ISS) in an effort to locate an ammonia leak in a critical radiator system, National Aeronautics and Space Administration (NASA) officials said. The American station commander and a Japanese crewmate left the orbiting laboratory Thursday morning. They will isolate plumbing to help flight controllers find the leak and open a spare radiator. The spacewalk started only hours after the station had to avoid a piece of space junk. Late Wednesday, thrusters on a docked Russian supply spacecraft were fired to move the ISS out of danger, but a computer error caused the thrusters to malfunction, and the station did not reach the desired altitude. NASA says the station and its 6 residents are safe despite their lower-than-intended orbit. The menacing debris is a satellite fragment