| CAPE CANAVERAL, Florida
CAPE CANAVERAL, Florida The crew of the newly repaired space shuttle Atlantis arrived at its Florida spaceport on Monday as NASA prepared to launch the ship on a mission to deliver a European space laboratory to the International Space Station.
The three-day countdown to Thursday's 2:45 p.m. EST liftoff of Atlantis from the Kennedy Space Center was due to begin later on Monday afternoon.
Meteorologists predicted a 40 percent chance the weather would be suitable for launch. Rain and clouds, however, could keep the shuttle grounded until Friday, when the forecast improves to an 80-percent chance of launch.
The U.S. space agency canceled two launch attempts in December because of problems with sensors in the shuttle's fuel tank. The sensors are part of a system to shut down the shuttle's engines to prevent a catastrophic explosion if they run out of fuel before reaching orbit.
"We can't afford to let the engines run dry because they tend to come apart," Atlantis' commander, Stephen Frick, told reporters shortly the crew arrived.
Fuel sensor glitches surfaced in 2005 during the first shuttle flights following the Columbia disaster in 2003, when the ship fell apart on re-entry into the atmosphere. The latest problems with the sensors appears to have been resolved.
"The sensor problem has been nagging us for quite a long time," Frick said. "We were able to pull the hardware out, find out what the problem really is and get a chance to fix it properly so we don't have to worry about it."
NASA also resolved a problem with a bent coolant hose discovered last week.
"We don't think we have any degradation in the system," said Charlie Blackwell-Thompson, a NASA manager overseeing Atlantis' launch preparations.
If the shuttle is launched on Thursday, it will reach the space station on Saturday for a week-long stay.
The Atlantis crew is scheduled to make three spacewalks to attach the European space laboratory, called Columbus, install experiments and tackle a few maintenance chores.
A fourth spacewalk NASA had been planning for Atlantis' mission was reassigned to the space station astronauts because of the delay in the shuttle's launch and was completed last week.
That spacewalk cleared the way for the installation of a Japanese laboratory complex, called Kibo, beginning in March.
In addition to the Columbus module, Atlantis will ferry a new crewmember to the station.
European astronaut Leopold Eyharts is scheduled for an abbreviated six-week stay on the orbital outpost to oversee the lab's setup and initial operations.
He replaces station flight engineer Dan Tani, whose planned two-month mission was extended by Atlantis' delayed launch.
"I'm anxious to get home and see my family," Tani, who celebrated his 47th birthday on Friday, said during an inflight interview on Monday.
Eyharts said he was eager to take Tani's place.
"I'm ready -- more than ready now," Eyharts told reporters at the Kennedy Space Center. "I hope that February will be the month of Columbus."
(Editing by Michael Christie and Cynthia Osterman)