At NASA's Kennedy Space Center in Florida, Mallory Jennings, left, and Heather Paul, aerospace engineers with Johnson Space Center's Spacesuit Life Support, perform a spacesuit demonstration during the STS-134 Tweetup event. About 150 people from 43 states, Washington, D.C., and half a dozen countries are participating in the event. A Tweetup gives followers of @NASA on the social messaging medium Twitter the opportunity to tour the center, view a shuttle launch and speak with NASA managers, astronauts, shuttle technicians and engineers. During the STS-134 mission, space shuttle Endeavour will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the International Space Station. Endeavour was scheduled to launch at 3:47 p.m. on April 29, but that attempt was scrubbed for at least 72 hours while engineers assess an issue associated with the shuttle's Auxiliary Power Unit 1. STS-134 will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Jack Pfaller