Strut-like shock absorbers then began to retract, drawing the two 100-ton craft together while creating an airtight seal between the shuttle and the station in the deadly vacuum of space.

"Good job. Welcome to the station," outpost flight engineer Jim Voss told the shuttle crew.

"Thank you, Jim. We're glad to be here," Lindsey replied.

The high-flying docking came at 11:08 p.m. EDT Friday (0308 GMT) Saturday -- or about 15 minutes later than planned -- as Atlantis and the international station flew 230 miles (368 kilometers) above the northeast coast of South America.

Onboard Atlantis: A five-member courier crew delivering the next major piece of the station - a $164 million airlock that will serve as a staging area for spacewalks to be conducted at the outpost when shuttles are not docked there.

Inside the station: A Russian skipper and two American flight engineers who were making last-minute preparations as their visitors executed a final graceful approach to the 17-story complex.

"Those guys are getting closer all the time," Voss told ground controllers as Atlantis closed in on the station.

"Better put the hot dogs on the burner for them," Canadian astronaut Bob Thirsk replied from NASA's Mission Control Center in Houston.

"Yeah, we're sweeping off the porch right now," Voss said.

Hatches between Atlantis and the outpost were scheduled to swing open about 12:30 a.m. EDT (0430 GMT) Saturday. The eight shuttle and station crewmembers then planned to carry out a dry run of their first big job - mounting the airlock to the outpost.

Limbering up the outpost's new $600 million robot arm, station flight engineer Susan Helms will go through the motions that will be required to snatch the 6.5-ton airlock from the shuttle's cargo bay and then move it up toward the starboard side of the U.S. Unity Module.

At the same time, Atlantis mission specialist Janet Kavandi will power up the shuttle's robot arm and practice her role in the airlock installation job: Hoisting spacewalkers up to the same site so they can help guide the chamber onto one of Unity's six berthing ports.

Set to begin about 10 p.m. EDT Saturday (0200 GMT Sunday), the dual robot arm operation will mark the first time that two construction-like cranes have been pressed into simultaneous service to carry out a station assembly chore.

And since the two arms will swing close to each other, mission managers decided a practice session would be prudent.

"It will be a dress rehearsal," said NASA flight director Paul Hill.

The dry run also will enable Helms to give the station's robot arm one final work out before the actual airlock installation -- a key considering that the 57.7-foot (17.5-meter) crane must be working properly to do the job.

The shuttle's 50-foot (15-meter) robot arm is to short to put the airlock in place, and a series of start-up problems with the station crane prompted a one-month delay in the Atlantis flight.

Those problems, however, were overcome in recent weeks, negating fears that a failure might leave the airlock stranded at the end of the station crane.

NASA nevertheless has put a back-up plan in place.

Should the mechanical limb fail, spacewalkers Michael Gernhardt and Jim Reilly will be ready to manually drive its wrist, elbow and shoulder joints so that the airlock can be raised up to the Unity berthing port.

"So we have really high confidence" that the job can be done, Hill said, "even in the worst-case scenario, if the arm was to fully die."

The seven-hour airlock installation job will feature the first of three spacewalks planned during the shuttle's weeklong stay at the station.

Four high-pressure oxygen and nitrogen tanks needed to replenish air supplies within the airlock are to be attached to the outer shell of the chamber during sorties scheduled for next Tuesday and Thursday.

Atlantis and its four-man, one-woman crew plan to remain at the outpost until July 21. The shuttle and its astronauts are due to land here at Kennedy Space Center at 1 a.m. EDT (0500 GMT) July 23.