By Irene Klotz
HOUSTON (Reuters) - Space shuttle Endeavour undocked from the International Space Station on Monday and headed home after delivering part of Japan's ambitious space laboratory.
A set of springs pushed the shuttle from its station port, then pilot Greg Johnson slowly backed Endeavour away as the two spacecraft flew 215 miles (347 km) above the Indian Ocean off the Australian coast.
"Endeavour departing," station crewmember Garrett Reisman said as, following naval tradition, a station bell rang out to mark the event.
"Copy, fair winds and following seas to you guys," shuttle commander Dominic Gorie radioed back.
Undocking was delayed about half an hour due to problems latching a station solar power panel in place to prevent its movement as the two ships separated.
NASA officials blamed the balky latch on a worn bearing, but said it was not thought to be a serious problem.
Johnson circled the shuttle around the station for a photo inspection of the $100 billion (50 billion pounds) outpost, then turned Endeavour on a path toward home.
The shuttle blasted off from Kennedy Space Centre in Florida on March 11 and was scheduled to land there at 7:05 p.m. EDT (11:05 p.m. British time) on Wednesday.
Endeavour's departure ended a 12-day station stay in which the shuttle crew installed the first piece of Japan's elaborate Kibo laboratory complex.
The main part of the lab, a 37-foot (11-metre)-long, tour bus-sized module, is due to launch aboard shuttle Discovery on May 25.
DEXTRE
The shuttle crew also completed its other primary task -- delivery and assembly of the Canadian robot Dextre, which will be used for maintenance work on the station exterior.
Before undocking, Endeavour astronauts and the station crew said goodbye with hugs and handshakes and closed the hatches between the spacecraft.
"We had a great time here," Gorie told the station crew. "It's a strange feeling to want to see your families but not want to leave a wonderful place."
Reisman, who flew up on Endeavour, replaced returning French astronaut Leopold Eyharts and will return with Discovery's crew in June.
"It's hard for me to believe that it's already finished," said Eyharts, who arrived last month to oversee setup of Europe's new Columbus laboratory.
NASA managers said Endeavour's mission, which included five spacewalks, had gone remarkably well and marked a major milestone in the life of the space station, now about 70 percent complete.
With the arrival of the Japanese Kibo segment, all 15 countries involved in the project were now represented on the station, said space station program manager Mike Suffredini.
"We truly have globalized the ISS (space station) at this point," he said.
"It is without a doubt the largest, most technologically challenging international project ever undertaken by human kind, and we as a people ought to be proud of where we are."
With plans to fly 10 more construction and re-supply flights to the station, NASA is trying to finish the orbital outpost by 2010 when the aging shuttle fleet is to be retired.
A final servicing mission to the Hubble Space Telescope is also planned for later this year.
(Additional reporting by Jeff Franks, editing by Vicki Allen)
