Mars, aliens and other Earths: My talk with the guy who has NASA’s ‘coolest job’

On July 20, 1976, the NASA Viking 1 lander touched down on the surface of Mars. It was the first time humanity had ever gotten a close look at our neighbor planet. Scientists had no idea what they might find - strange rock formations, unfamiliar soil, maybe even alien life?

The experiments aimed at identifying Martian organisms turned up negative, or inconclusive, and decades of further exploration failed to find signs of life on the red planet. But at an event at NASA Langley Research Center Wednesday in honor of Viking's 40th birthday, NASA scientists said the search isn't over yet.