The Atlantis astronauts plan to deliver and install the central segment of what eventually will become the 356-foot-long backbone of the station.

Strictly speaking, as one official said, the Atlantis astronauts had achieved two of three objectives.

As soon as the festivities were over, the Atlantis astronauts began hauling more than 5,000 pounds of supplies to the Russian station, including water.

The Atlantis astronauts would have guided them.

During the mission, the Atlantis astronauts are to continue medical studies of how humans react to he rigors of spaceflight.

A21 The Atlantis astronauts passed a tricky test.

After a brief welcoming ceremony by the station crew, Atlantis astronauts received the standard station safety briefing.

The supplies and equipment that Atlantis astronauts delivered to the orbiting outpost is expected to keep the station well supplied through 2012.

Earlier on the day, Atlantis astronauts used the maneuvering thrusters of the shuttle to boost the Space Station to a slightly higher orbit.

For the next three days the Atlantis astronauts will do scientific experiments and prepare for a return to Earth.