Indian American astronaut Sunita Williams bade an emotional adieu to the seven-member Space shuttle Discovery astronauts who left the orbiting laboratory to begin the two-day journey back to earth.
Discovery is due to land at NASA's Kennedy Space Center on Friday. It must land no later than Saturday because of supply limitations.
"We bid a bittersweet farewell to Discovery," Expedition 14 commander Micheal Lopez Alegria said during a brief ceremony. "We'd like to welcome Suni to our crew."
With this came an end to the STS-116 crew's stay at the International Space Station.
During its eight-day visit, the crew added a new truss segment to the station, delivered a new crew member and rewired the orbital outpost's power system.
Sunita, who arrived at the station with the STS-116 mission, replaced European Space Agency Astronaut Thomas Reiter on the Expedition 14 crew. She will remain a member of Expedition 14 until Commander Michael Lopez-Alegria and Flight Engineer Mikhail Tyurin are relieved by Expedition 15 in March 2007.
Sunita will finish her remaining time of her six-month tour of duty on the station as a member of Expedition 15.
Reiter will return to Earth with STS-116.
"I hope Discovery takes you home as smoothly and safely as it brought me here," Sunita told Reiter.
"It's been an exciting time, so it's hard to let go," Reiter said before leaving the space station. "I'm really excited to get back on the ground."
STS-117 is scheduled to visit the station in March.
NASA and the Russian Federal Space Agency have named two astronauts and two cosmonauts to the next International Space Station crew, known as Expedition 15.
Astronauts Clayton Anderson and Daniel Tani will travel to the station next year and work as flight engineers.
Cosmonauts Fyodor Yurchikhin and Dr. Oleg Kotov will spend six months aboard the orbiting laboratory.
During their eight days docked to the station, the Discovery crew continued the on-orbit construction of the station with the addition of the P5 spacer truss segment during the first of four spacewalks.
Mission Specialist Bob Curbeam participated in all of them, giving him the record for the number of spacewalks during a single shuttle mission.
He teamed up with Sunita for third spacewalk, and with Mission Specialist Christer Fuglesang for the other three.
The first spacewalk was for the P5 truss segment installation, the second and third focused on the power reconfiguration, and the fourth was dedicated to completing retraction of the port solar wing of the P6 truss.
The P6 arrays were deployed in late 2000. On Wednesday, almost half the port wing was retracted, leaving 17 bays out.
On Saturday spacewalkers Curbeam and Sunita helped retract six more bays.
In a dramatic Monday spacewalk, Curbeam and Fuglesang helped complete the retraction. Besides delivering a new crew member, Discovery delivered more than two tons of equipment and supplies to the station.
Almost two tons of items no longer needed on the station will return to Earth with STS-116. With Pilot Bill Oefelein at the controls, Discovery slowly moved away from the station.
A partial fly-around of the station gave the crew a look at the orbiting laboratory, with its new P5 spacer truss segment and the port wing of the P6 solar array fully retracted and firmly secured in its retention box.
