CAPE CANAVERAL, Fla. -- NASA fueled space shuttle Atlantis on Monday for an afternoon liftoff to the space station, despite increasingly cloudy skies.

Forecasters put the odds of acceptable weather at 70 percent, not nearly as good as previous days. Low clouds were the main concern for the 2:28 p.m. liftoff.

The six astronauts woke up around the time fueling got under way well before dawn. Three hours later, the external fuel tank was full and the countdown right on track.

Atlantis is loaded with big spare parts for the International Space Station. NASA wants to stockpile as much equipment there as possible before the shuttle fleet is retired next year.

The 11-day flight will keep the astronauts in orbit through Thanksgiving. They will unload nearly 30,000 pounds of pumps, tanks and other spare parts, as well as science experiments. Three spacewalks will be conducted to carry out the work and get a jump on the next shuttle flight.

It is NASA's last shuttle flight of the year and among only six remaining.

Gathering for the launch were about 100 Twittering space fans who won invitations from NASA. They were among the first to sign up online last month for this first-ever launch "tweetup."

NASA put up a big white circus-like tent at the press site of Kennedy Space Center, expressly for the Twitter crowd.

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