Will.i.am and Leland Melvin at the MSL Tweetup

Will.i.am, left, celebrity entertainer and member of The Black Eyed Peas, and former astronaut Leland Melvin, NASA associate administrator for Education, take part in a Tweetup at NASA Kennedy Space Center's Press Site in Florida during prelaunch activities for the agency’s Mars Science Laboratory (MSL) launch. Behind them glint the lights of the launch countdown clock. Once MSL and Curiosity have landed on Mars, the rover will investigate whether the region has ever offered conditions favorable for microbial life, including the chemical ingredients for life.

Image Credit: NASA