NASA began fueling the space shuttle at daybreak. The launch is scheduled for 4:31 p.m. EST.
After the drama of changed plans and elaborate fixes during the last shuttle flight, Atlantis commander Steve Frick tells he's ready for anything.
"We have to think about what might happen, but we stay focused on what we're planning on doing, hoping to do, what we're really knowledgeable in, and then we'll deal with what happens," the astronaut said.
"We have to play the cards we're dealt - we talked about that amongst the crew - you never know what cards are going to show up when you get there," agreed astronaut Rex Walheim. "The situation may not be exactly like you planned, and so we have to rely on our training to have the skills and do the types of tasks that we need to do."
Each of the year's previous shuttle countdowns have ended with an on-the-dot departure, and NASA hopes to make it four in a row with Atlantis. It will carry a crew of seven and Europe's long-awaited space station lab, named Columbus.
About 750 Europeans connected to the scientific laboratory - a $2 billion project begun nearly a quarter-century ago - were in town for the launch and expected to gather at the space center.
Columbus is "our cornerstone, our baby, our module, our laboratory," said Alan Thirkettle, the European Space Agency's station program manager.
"This module is the first step in the process of making the international space station an international research lab, to do the science that the thing is being built for," says CBS News space consultant Bill Harwood. "So I think on both sides of the ocean folks are very eager to get Columbus into orbit and hooked up."
Columbus will be the second laboratory added to the international space station. NASA's Destiny lab made its debut in 2001, and Japan's huge lab Kibo - which means hope - will go up in three sections beginning on the very next shuttle mission in February.
Columbus adds another 2600 cubic feet of work and living space to the every growing space station, reports King.
"I tell you, us shuttle guys, we're just hoping not to get lost," said Frick.
Scientific work will start almost immediately inside Columbus, which is essentially packaged and ready to go.
Harwood says this will be an active shuttle mission.
"Three pretty busy spacewalks to get Columbus all hooked up properly, and then, if they can, they're going to extend two days to add a fourth spacewalk to go out and inspect the solar array, that rotary joint, remember, from last mission, that had some contamination in it," said Harwood. "They want to go take a real close look at that to figure out what might be causing that problem."
French astronaut Leo Eyharts will spend three months aboard the international space station. Not only will he be the first astronaut to work in the new Columbus laboratory, he tells CBS News he's bringing the ingredients for several French meals as a treat for his crewmates.
Eyeharts sees Columbus as "the start of our permanent work in space" and calls being chosen for the mission "a great honor."
Thirkettle sees Columbus as a stepping stone for Europe to the U.S.-led moon expeditions planned for late in the next decade. To gear up for that, NASA is under presidential orders to finish the space station and retire its three remaining shuttles in 2010.
Counting Atlantis' upcoming flight, that leaves 12 shuttle missions to the space station and one, next summer, to the Hubble Space Telescope.
NASA Administrator Michael Griffin said he doesn't expect that number to change, which means some space station equipment and experiments will never make it up.
Aside from the interruption caused by the 2003 Columbia tragedy, the actual building of the space station in orbit has gone well, Griffin said. That's in stark contrast to the space station's planning and development, which dragged on for years and contributed to Columbus' prolonged grounding.
"We the United States, as the senior partner in the space station coalition, did not plan it well," Griffin said on the eve of Columbus' launch. "It has taken far too long and I'll just leave it at that."