The Discovery shuttle on Saturday undocked from the International Space Station before heading back to Earth with six astronauts aboard, NASA said.
"The undocking of discovery confirmed at 5:08 (am) central time (1538 IST)," NASA television said.
Discovery's astronauts will scan their spaceship's heat shield one last time for potential micrometeorite impacts before flying back to Earth.
The shuttle will remain 74 km from the ISS so it can return to the orbiting laboratory if serious damage is found.
The shuttle is scheduled to land at the Kennedy Space Centre in Cape Canaveral, Florida, on Monday.