For US astronauts, a long time in space

,Two American astronauts who have been in orbit for six months cheerfully broke NASA's space-endurance record, but said they have no intention of going after the world record of more than a year.

Former space-station residents Daniel Bursch and Carl Walz, now living aboard the docked shuttle Endeavour, sailed into the history books late Tuesday night.

They were asleep at the time.

Shortly before bedtime, though, Mission Control reminded them that they soon would be breaking the 188-day, four-hour mark set by astronaut Shannon Lucid in 1996 aboard Russia's old Mir space station.

"Of course, you all have a long ways to go if you're going to break the all-time single-flight record of about 438 days," Mission Control said. "Do we have any volunteers today to go for that record, or will you guys be satisfied with the one you have?"

Mr. Bursch, Mr. Walz, and their Russian commander, Yuri Onufrienko, nodded their heads. "I'm very happy," Bursch said.

The three will have spent 194 days in space by the time they return to Earth on Monday. That's one day longer than Mr. Onufrienko's previous flight, on Mir in 1996.

"I'm ready to come home," Bursch said, noting it was a record he hadn't been shooting for. "I don't think my family was shooting for it, either," added the father of four. NASA extended the crew's mission by a month, back in March, in order to squeeze in extra space station repairs during Endeavour's visit.

Flight director Rick LaBrode said Bursch, Walz and Onufrienko have been "nothing but positive and really go-getters" from the time they rocketed into orbit on Dec. 5.

Two of their shuttle colleagues, meanwhile, wired up and bolted down a work platform Tuesday that will allow the space station's 58-foot robot arm to roam the orbiting outpost.

Tuesday's spacewalk was the second this week. Chang-Diaz and Perrin will go out one last time on Thursday to tackle their most challenging job: robot-arm wrist surgery.