NASA, which has tiptoed into the new world of social media with Twittering astronauts and Facebooking rovers, is taking the next step with an invitation-only outreach to the twedia to cover a space shuttle launch.

There are so many details to work out that the so-called TweetUp, originally planned for next week's launch of space shuttle Endeavour, has been rescheduled for the August flight of shuttle Discovery, said Michael Cabbage, a spokesman for the U.S. space agency.

NASA figures it can handle between 100 and 150 Twitterers and bloggers in a makeshift media site at the Kennedy Space Center in Florida.

Twitter is an Internet-based text message service that allows users to post updates -- called tweets -- of no more than 140 characters. In this instance, media members at the launch will be able to issue reports to Twitter users who have signed up to receive them. The tweets also are posted and archived on the Twitter.com website.

NASA is still deciding whom to invite, how to accommodate Twittering media's need for high-speed Internet service and whether to restrict the TweetUp to U.S. citizens, among other issues.

Security measures implemented after the September 2001 attacks on New York and Washington prohibit foreign nationals from unescorted access to the spaceport.

If we don't limit it to media outlets only, we would have a standing line for those coveted 150 slots that would stretch around the world, said NASA spokesman Bill Johnson.

TWEET LEADER

George Whitesides, an Obama administration appointee at NASA, said it has been a priority of the new president to engage the public directly with social media tools.

NASA is taking a leadership role in this, Whitesides said at a space development conference in Orlando last week.

These things matter more than you might think, he added. More people follow CNN on Twitter than those who watch CNN during prime-time hours.

More than 350,000 people followed updates from astronaut Michael Massimino, aka Astro_Mike, on Twitter during NASA's last shuttle mission to refurbish the Hubble Space Telescope.

The tweets weren't exactly live, however.

Massimino emailed his messages to Mission Control in Houston as time and radio communications allowed. Public affairs officials then posted the passages on Twitter.

Astronaut Mark Polansky (Astro_127), commander of the shuttle Endeavour crew, plans to follow the practice during his upcoming construction mission at the International Space Station, which is scheduled for launch on June 13.

It serves as a good way to educate folks as to what's going on in the program, Polansky said.

I'll be the first the admit that I didn't know a tweet from a Twitter from a Facebook from a MySpace before I got into this, but as I've done it, I've learned that there's a whole community of people that love this stuff and are following, said Polansky, who as of Monday had 14,614 followers.

People just love to see on a daily basis what you're doing and feel like they're getting a real insider's view of what's going on, he said.

NASA hasn't limited its electronic incarnations to living beings.

One of its first and most popular Twitter feeds belongs to the Mars Phoenix rover. And Phoenix, along with sister rovers Spirit and Opportunity, have a host of fans on Facebook.

(Editing by Jim Loney and Philip Barbara)

Florida NASA Launch Twitter