When NASA astronaut Joseph Acaba went out for a spacewalk during a recent trip into space, he held on tight to the railing. That's because Acaba is afraid of heights. That was one of the highlights of Acaba's talk this week to employees at the Stennis Space Center on the Mississippi Gulf Coast. Acaba was making his first public appearance since returning Feb. 28 from the International Space Station. He says during the next year or so NASA astronauts will be flying on commercial flights, calling it a "big step." He says going to space is difficult and will never become routine but in the near future there will be more opportunities for people to fly there. He says the ultimate goal is to get humans to Mars.