The International Space Station is back to full strength with the arrival of four new astronauts. SpaceX delivered the U.S., French and Russian astronauts to the orbiting lab on Saturday, a day after launching them. They are replacing a crew that bailed early last month because of health concerns. It was NASA's first medical evacuation in 65 years of human spaceflight. The orbiting lab is now back to seven residents, allowing spacewalks to proceed and research to pick back up. They're expected to remain on board for eight to nine months.
