Two astronauts from the US shuttle Discovery completed Sunday a second spacewalk as part of efforts to replace a depleted ammonia coolant tank outside the International Space Station.

Astronauts take 2nd spacewalk to replace space station cooling tank, overcome stiff bolt. Spacewalking astronauts had to pull out a hammer and pry bar while attaching a big, new tank full of ammonia coolant to the International Space Station on Sunday, successfully driving in a stiff bolt after two frustrating hours.

Today in History. Today is Sunday, April 11, the 101st day of 2010. There are 264 days left in the year.

Houston, we have an auction: Emergency checklist from Apollo 13 flight up for sale in NYC. The emergency checklist from the Apollo 13 aborted moon landing is being auctioned in New York City.

Former astronauts call US decision to cancel moon landing program disappointing. Two former astronauts have said they are disappointed with the U.S. government's decision to cancel NASA's moon landing program.