NASA Administrator Charles Bolden visits to the Jet Propulsion Laboratory in Pasadena, Calif., on Thursday, May 23, 2013. Bolden inspected a prototype spacecraft engine that could power an audacious mission to lasso an asteroid and tow it closer to Earth for astronauts to explore. Bolden's visit comes a month after the Obama administration unveiled its 2014 budget that proposes $105 million to jumpstart the mission, which may eventually cost more than $2.6 billion. (AP Photo/Nick Ut)