Live coverage: International crew lands in Kazakhstan

Four veteran astronauts have been selected to train for launch aboard new commercial crew capsules being built by Boeing and SpaceX that are intended to ferry astronauts to and from the International Space Station starting in 2017, NASA announced Thursday.

Two astronauts floated outside the International Space Station early Friday for the first of four planned spacewalks to wrap up a complex multi-year job to replace 48 aging batteries in the lab’s solar power system with 24 more powerful lithium-ion units.

Watch the pre-launch news conference held Monday, March 21 at NASA’s Kennedy Space Center to preview liftoff of the Orbital ATK commercial Cygnus cargo ship aboard a United Launch Alliance Atlas 5 rocket for the International Space Station.