The U.S. space program is nearing the end of an era as the space shuttle Atlantis is now in the middle of its last trip into space before retirement. There will be just two more shuttle launches before NASA retires the whole fleet.

The shuttle's achievements include taking 185 astronauts into orbit over two-and-a-half decades. Atlantis blasted off from Cape Canaveral, Fla. and is now on its 32nd and final mission.

Atlantis is the first shuttle to be retired as NASA completes construction of the International Space Station and winds down the shuttle program.

The six veteran astronauts on board are on a 12-day mission. Ken Ham, the shuttle's commander, said they were happy to take the spacecraft on its farewell tour before retirement.

The crew's main assignment is to deliver a new russian-built docking port and tons of supplies to the International Space Station.

"I don't celebrate too much until we've really gotten through the mission, and we got wheels stopped, and I can take a break and think about things," said Bill Gerstenmaier, NASA deputy administrator.

There is a possibility Atlantis could fly again and will be prepped in case it is needed for a rescue mission. The shuttle could also go on another supply run to the space station if the White House approves.

Two other official space shuttle missions are scheduled this year before the program wraps up -- one for Discovery and the other for Endeavour.

For now, it is Atlantis' turn to enjoy, one last time, the part of God's creation known as outer space.