The astronauts speak to reporters after touching down at the Kennedy Space Center runway. Photo: NASA TV/Spaceflight Now

The next crew to take up residence aboard the international space station and their four shuttle crewmates who will share the ride into orbit arrived at Kennedy Space Center on Sunday afternoon in preparation for Thursday evening's blastoff.

Endeavour remains poised to rocket away from pad 39B at 7:41 p.m. EST (0041 GMT). Countdown clocks are slated to begin ticking at 11 p.m. EST Monday.

The Expedition Four crew of Russian commander Yuri Onufrienko and American flight engineers Carl Walz and Dan Bursch are headed to space station Alpha for a five-month voyage. During their tenure, science research will continue and the outpost will grow as it receives the first section of the backbone truss structure.

The three men will replace the Expedition Three trio of commander Frank Culbertson, pilot Vladimir Dezhurov and flight engineer Mikhail Tyurin following their four-month mission. Expedition Three will come home aboard Endeavour.

The shuttle's crew is led by commander Dom Gorie, with pilot Mark Kelly and mission specialists Linda Godwin and Dan Tani.

The astronauts flew from their Houston training base to Kennedy Space Center in five T-38 jets, touching down on the spaceport's shuttle runway at 4:40 p.m. EST (2140 GMT).

"It's just a beautiful day to arrive for a wonderful flight," commander Gorie told reporters gathered at the runway. "This whole crew is ready to fly. Our most important mission is bringing these three Expedition crew members up to the space station and bringing Expedition Three home. We are ready to do that and looking forward to a launch on Thursday night. We'll just hope the weather stays like it is and we're going to have a wonderful flight."

On Sunday evening, the astronauts were scheduled to tour the launch pad and inspect Endeavour's payload bay before the bay doors are closed for flight. The next three days will be spent reviewing flight plans, undergoing medical exams, practicing landing approaches in the shuttle training aircraft and relaxing with family members.

In addition to carrying a cargo module that will be temporarily attached to the space station for unloading, Endeavour is also taking thousands of items to orbit in honor of victims from the September 11 terrorist attacks on America.

The most recent cargo list shows one large U.S. flag recovered from the World Trade Center, one large Marine Corp. flag recovered from the Pentagon, one large U.S. flag that flew on the Pennsylvania state capitol on September 11, 6,000 four-inch by six-inch U.S. flags on cardboard that will be given the families of victims after the flight, 23 New York Police shields, 91 New York Police patches, one New York Fire Dept. flag and one New York Fire Dept. poster with pictures of those who were killed.

Endeavour's mission, its 17th overall, is scheduled to last 11 days. Landing is planned for December 10 at Kennedy Space Center.