The space shuttle Endeavour has departed the International Space Station, clearing the way for a final cargo run to the outpost before NASA retires its three-ship fleet.
As the spacecraft sailed 215 miles (345 kilometers) above Bolivia, pilot Greg Johnson gently pulsed Endeavour's steering jets at 11:55 p.m. ET on Sunday to back away from the docking port that has anchored the shuttle since its arrival on May 18.
Endeavour delivered the station's premier science experiment — the $2 billion Alpha Magnetic Spectrometer particle detector — and a pallet of spare parts intended to tide over the orbital outpost after the shuttle program ends.
"Endeavour departing," radioed station flight engineer Ron Garan. "Fair winds and following seas, guys."
"Thanks, Ron," replied Endeavour commander Mark Kelly. "Appreciate all the help."
Afterward, Endeavour maneuvered to within about 950 feet (290 meters) of the station to test a new automated rendezvous system being developed for NASA's next spaceship, the Multi-Purpose Crew Vehicle, which is intended to fly astronauts to the moon, asteroids and eventually to Mars.
"We're now separating — that's the closest we're going to get," Kelly radioed to Garan.
Then Kelly fired the shuttle's thrusters, and Endeavour pulled away from the space station for the last time. NASA plans to decommission Endeavour, its youngest shuttle with 25 voyages, and send it to a museum in Los Angeles for display.
One final shuttle mission is planned before the United States ends the 30-year-old shuttle program. Atlantis is due to launch July 8 with a year's worth of supplies for the station, a contingency plan in case the commercial companies hired to take over supply runs to the station encounter delays with their new vehicles.
The shuttles are being retired to save the $4 billion annual operating expenses so NASA can develop new vehicles that can travel beyond the station's orbit.
During its 12 days at the station, the Endeavour crew conducted four spacewalks to complete construction of the U.S. side of the $100 billion outpost, a project of 16 nations that has been being assembled in orbit since 1998.
Endeavour is due back at the Kennedy Space Center in Florida at 2:35 a.m. EDT Wednesday, the same day sister ship Atlantis is scheduled to reach the launch pad for NASA's 135th and final flight.