The astronauts for NASA's next-to-last space shuttle flight returned to Florida on Thursday for another try at launching to the International Space Station.


The six crewmen -- led by the husband of Rep. Gabrielle Giffords -- arrived at Kennedy Space Center a day before the countdown clocks begin ticking again.

Shuttle Endeavour is due to blast off Monday morning. The first launch attempt on April 29 was halted by electrical trouble. A switch box was replaced, and new wiring installed.

In brief remarks after the crew's arrival, commander Mark Kelly said the launch director has assured him that Endeavour is "in great condition."

Aboard Endeavour is a $2 billion particle physics detector that will be attached to the space station. The 16-day flight also will feature the delivery of station spare parts, as well as four spacewalks that will be the last for the 30-year shuttle program. Atlantis closes out the shuttle era with a flight in July.

Kelly's wife was critically wounded in the head four months ago at a Tucson, Ariz., political event. The Arizona congresswoman recovered well enough to travel from Houston for her husband's first launch effort. She will return to Kennedy later this week, along with the other astronauts' families.

Her staff said she will return to Houston to continue rehab, shortly after liftoff. She is a member of the House committee on science, space and technology.

Astronaut Gregory Chamitoff commended Kelly for giving the mission his all, and called him "truly an amazing commander."

"We all know Mark's been through a lot the past few months," Chamitoff told journalists. "All of us feel really, really lucky to have him guide us through this complex mission."

"Appreciate that," Kelly said. "We are really excited to be here, excited to launch hopefully on Monday if the weather holds."

Forecasters put the odds of acceptable conditions at 70 percent. Launch time is 8:56 a.m.

Pilot Gregory Johnson celebrated his 49th birthday Thursday.

"I can't think of a more perfect way to spend my birthday" than get ready for the flight, Johnson said.

Endeavour is the youngest shuttle in the fleet. It was built to replace the shuttle Challenger, destroyed in a 1986 launch accident, and first flew in 1992. This will be its 25th flight and the 134th overall for the shuttle program.