NASA's Jet Propulsion Laboratory in Pasadena, Calif., will host a Tweetup on Monday, June 6. More than 100 NASA Twitter followers, who registered in April, will attend the event. With four NASA/JPL space missions launching in 2011 and an asteroid belt encounter nearly underway, this year will be one of the busiest ever in planetary exploration. Tweetup participants will interact with JPL scientists and engineers about these upcoming missions: Aquarius, to study ocean salinity; Grail, to study the moon's gravity field; Juno to Jupiter; and the Mars Science Laboratory/Curiosity rover. Tweetup participants also will learn about the Dawn mission and its planned encounter with the asteroid Vesta. Read more