NASA and SpaceX crew of four blast off to ISS

NASA and SpaceX's Dragon spacecraft blasted off carrying four astronauts from four countries to the International Space Station on Saturday.

The Crew-7 mission expected to last more than six months aboard the ISS, where they will carry out science experiments including collecting samples during a spacewalk to determine whether the station releases microorganisms through its life-support system vents. Another experiment will aim to assess the physiological differences between sleep on Earth and in space.

The crew is expected to dock at the space station on Sunday. The astronauts will join the seven astronauts already on the orbiting laboratory. The Crew-7 astronauts will spend about five days taking over operations from the SpaceX Crew-6 astronauts, who have been on the space station since March.