Actor Matt Damon, who stars as NASA Astronaut Mark Watney in the film “The Martian,” participates in a question and answer session, Tuesday, Aug. 18, 2015, at the United Artist Theater in La Cañada Flintridge, California. NASA scientists and engineers served as technical consultants on the film. The movie portrays a realistic view of the climate and topography of Mars, based on NASA data, and some of the challenges NASA faces as we prepare for human exploration of the Red Planet in the 2030s.