Astronomers from NASA have discovered a huge asteroid that was about to hit Earth on Friday at 10:30 A.M EST. NASA

Twenty lucky followers of NASA's Twitter account will get behind-the-scenes access at the launch of the agency's next Earth-observing satellite mission. They will participate in a daylong Tweetup program at Vandenberg Air Force Base in California on Thursday, Oct. 27 and view the launch of NASA's NPP satellite, which is scheduled to lift off aboard a United Launch Alliance Delta II rocket between 2:48 and 2:57 a.m. PDT on Friday, Oct. 28. The National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) will collect critical data on long-term climate change and short-term weather conditions. With NPP, NASA continues gathering key data records initiated by the agency's Earth Observing System satellites, monitoring changes in the atmosphere, oceans, vegetation, ice and solid Earth.

Tweetup participants were selected from more than 625 people who registered online. They will share their experiences with their followers through the social networking site Twitter. Attendees are coming from California, the District of Columbia, Illinois, Kansas, New York and Oregon. Beginning at 9:30 a.m. PDT on Oct. 27, NASA will broadcast a portion of the Tweetup when attendees talk with NASA Astronaut Piers Sellers, the deputy director of the Sciences and Exploration Directorate at NASA's Goddard Space Flight Center in Greenbelt, Md.; NPP Project Scientist Jim Gleason; NPP Systems Manager Janice Smith; NASA Launch Director Tim Dunn; and Scott Asbury, a senior program manager with Ball Aerospace & Technologies, Corp. in Boulder, Colo. To watch the broadcast, visit:

Participants also will tour Vandenberg's launch facilities, including a visit to the launch pad. Vandenberg is headquarters for the 30th Space Wing, which manages space and missile testing for the Department of Defense and places satellites into polar orbit from the West Coast using expendable boosters. Launch management for the mission is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida.

NASA has invited its Twitter followers to seven previous launches, but this is the first from the West Coast. To follow participants on Twitter as they experience the prelaunch events and NPP's liftoff, follow the #NASATweetup hashtag and the list of attendees at: