Atlantis heads back to Earth on final mission

Atlantis heads back to Earth on final mission

The space shuttle Atlantis undocked Sunday from the International Space Station (ISS) and headed back to Earth to complete its final mission after successfully delivering tons of supplies.

The shuttle uncoupled from the orbiting space laboratory at 11:22 am (1522 GMT) after its six-member crew unloaded the last equipment, which included a crucial communications antenna, power storage batteries and a radiator.

The biggest single element was the five-ton Rassvet research module, or MRM-1, which will provide additional storage space and a new docking port for Russian Soyuz and Progress spacecraft.

The Rassvet -- "Dawn" in Russian -- was permanently attached to the bottom of the space station's Zarya module. It carries important hardware on its exterior including a radiator, airlock and a European robotic arm.

Astronauts completed the 12-day mission's final spacewalk on Friday, plugging a new ammonia jumper cable into the station, transferring a grapple fixture from the shuttle to the station and reconfiguring some tools.

The trip back to Earth caps the 25-year career of one of NASA's iconic spacecraft. The shuttle, which has logged some 115 million miles (185 million kilometers), is due back in Florida Wednesday at 8:44 am (1244 GMT).

Only two more shuttle launches remain -- one in September for Discovery and the final blast off for Endeavour in November -- before the curtain falls on this era of human spaceflight.

The United States will then have to rely on Russia to take astronauts to the station aboard three-seater Soyuz spacecraft until a new fleet of commercial "space taxis" is operational.