Atlantis lifted off from Kennedy Space Center (KSS) at 8:45 a.m. Eastern Daylight Time (12:45 GMT) Friday on a mission to make the station ready for its first occupants set to arrive in late October. During their stay at the orbital outpost, the seven-person crew will make one spacewalk and deliver supplies and install equipment.

Late Friday night, Commander Terry Wilcutt and pilot Scott Altman completed the first of several thruster burns to align Atlantis with the station. Both vehicles orbit Earth about every 90 minutes and are flying at roughly 17,000 miles (27,400 kilometers) per hour.

Wilcutt, who has made two trips to the Russian space station Mir, said the docking maneuver isnt difficult, but requires finesse.

"It's not a difficult thing, but it is very delicate when you've got space vehicles that weigh 200,000 pounds [90,720 kilograms] apiece and you're going to bump them together, then you have to do that very carefully," he said.

During the final closure between the two vehicles, the orbiter will advance at about only one inch (2.54 centimeters) each second.

One curve thrown into the mix is the unusual failure of one of the two star trackers aboard Atlantis used to check the orbiters position.

Lead flight director Phil Engelauf said using the remaining tracker, which faces a different direction than the other, will require another maneuver to position the orbiter to get a position fix. Both units are in the nose of the orbiter, with the failed unit looking up and the other looking over Atlantis left wing.

He added the crew has trained for the procedure and said "Its best to be trained for rather than have to deal with it in real time."

As an additional backup, the commanders optical landing sight, known as a "heads up" display, can be used as a star tracker.

Atlantis should dock with the station at about 1:53 a.m. Sunday (05:53 GMT) at an altitude of about 220 miles (354 kilometers) over the Russia and Kazakhstan border north of the Caspian Sea.

Late Friday evening the rest of the crew went about their tasks to prepare for docking. Rick Mastracchio checked out the 20-foot (6 -meter) long Spacehab module in the payload bay containing supplies to be moved to the station. Items to be transferred range from foodstuffs to electrical parts and even a computer printer. Mastracchio also unlimbered and tested the orbiters 50-foot (15-meter) robot arm, which will ferry the two spacewalkers to their initial work site on the station.

Ed Lu and cosmonaut Yuri Malenchenko also began checking out their spacesuits in preparation for their spacewalk early Monday morning. Dan Burbank, who will coordinate the spacewalk, checked out a spare suit.

During the crews lunch break early Saturday morning, there was time for some microgravity antics. Lu tossed what looked like peanuts to cosmonaut Boris Morukov, who caught them with his mouth.

Bill Gerstenmaier, a shuttle program manager, said the decision to extend the mission would come about the third or fourth day of the flight. At issue is the orbiters usage of power from the fuel cells that mix oxygen and hydrogen to generate electricity along with propellant used by the maneuvering thrusters. If usage goes as planned or lower, then Atlantis will spend one more day at the space station.

"Our analysis shows we can support a 12-day mission and thats what were aiming for," he said. "We just need to get the data back on actual usage to confirm that."

Back at Kennedy Space Center, technicians are preparing to roll Space Shuttle Discovery to the launch pad in preparation for an October 5 launch. During that mission, four spacewalks will attach the Z-1 truss, a cornerstone of the stations structure and a tunnel-like pressurized adapter for the stations modules.