5, 4, 3, 2, 1 .... TWEET!

CAPE CANAVERAL, Fla. — Fingers will be flying when space shuttle Atlantis blasts off Monday: About 100 of NASA's geekiest fans will be on hand, pecking away at iPhones, BlackBerrys, laptops and other Twittering gadgets.

They plan to let loose with electronic messages — provided they aren't so swept away by the afternoon liftoff that they fall uncharacteristically silent for a moment or two.

``I'll be uploading stuff as it happens,'' promised Steve Wake, 38, a computer programmer who flew in from Denver. ``On launch day, who knows? I may be too excited about everything else to even think about doing that stuff. When it's over with, I'm sure I will.''

Laura Burns already has a strategy. She figures she'll have the words typed in and her finger hovering over the button so she can send a tweet at the moment of liftoff.

``I'll have to be like juggling my iPhone and my camera and my eyes, and trying to get everything all at once,'' said Burns, 33, a software systems engineer from Columbia, Md. She's using the Twitter name ``moonrangerlaura'' to chronicle her entire trip — including the drive to Cape Canaveral and a pit stop for MoonPies.

For the first time ever, NASA last month invited its Twitter followers to sign up online for the chance to see a space shuttle launch up close.

The 100 slots — and 50 backup positions — filled in less than 20 minutes Oct. 16.

The two-day gathering got under way Sunday at Kennedy Space Center with talks by NASA bigwigs, including the first Twittering astronaut, Michael Massimino, aka Astro—Mike. The discussions were streamed live on the Internet, and the ``tweetup'' gathering was near the top of Twitter's trending topics Sunday morning.

Nearly half the attendees are from Florida, making for an easier trip, especially if the mission ends up being delayed. Atlantis' six astronauts have thousands of pounds of spare parts to deliver to the International Space Station. The 11-day flight will keep the astronauts in orbit over Thanksgiving.

Monday's launch time is 2:28 p.m. EDT, 1:28 CDT. Excellent weather is forecast.

The tweeps, as they're called, represent 21 states plus the District of Columbia, as well as five countries, including Morocco and New Zealand. They're traveling on their own dime.

NASA estimates the 100 have more than 150,000 Twitter followers. It's a dream outreach program for a space agency looking to drum up support.

With only six shuttle flights remaining and still no word from the White House on a future course for astronauts, NASA is tapping into social media — Twitter, Facebook and the like — to spread its stay-in-space message.

Astronauts have been tweeting from Earth and orbit since spring. While NASA already has held a few of the tweetups — so-called meet ups of people who use Twitter — it's the first for Kennedy Space Center, a high-security area requiring government clearance.

Even the most staid NASA types see the benefit of reaching out to a younger, hipper crowd.

Atlantis commander Charles Hobaugh — who acknowledged last month he doesn't even text message — assigned the crew's Twittering tasks to Dr. Robert Satcher Jr. Satcher, who will become the first orthopedic surgeon in space, uses the handle ZeroG—MD.

``It's exciting that this is generating more interest in space exploration and certainly interest in the last few missions of the shuttle, which we hope are not the last few missions of the shuttle,'' Satcher said.

With five children of his own, the director of NASA's space shuttle program appreciates the importance of reaching out to the next generation.

``It's the right thing to do, is to use the tools available and get them excited about things that are real, not virtual,'' program director John Shannon said.

Neal Wiser, a 41-year-old Internet marketing strategist from Philadelphia, is fulfilling a lifelong dream. The biggest thing he's ever seen lift off is an 8-foot model rocket.

This is Wiser's third NASA tweetup. He'll be blogging and Twittering throughout.

``We're all geeks together,'' he said. ``I actually joked to my wife that I'm turning into a NASA groupie.''