NASA Astronaut Explains Why We Should Send Humans To Mars (VIDEO)

08/17/2011 02:34 pm ET | Updated Oct 17, 2011

As NASA shutters its space shuttle program and abandons its plans to return to the moon, why has the agency embarked on an ambitious new plan to send astronauts to Mars?

NASA astronaut Rex Walheim, one of the crew members onboard the final space shuttle mission, says sending humans to the Red Planet is necessary to determine whether there has ever been life on Mars.

“There have been a lot of clues we’ve seen that there is potentially life on Mars, but the only way to find out is really to go there,” he told The Huffington Post during a community event held by NASA on Wednesday in New York City. “It is somewhat of a similar planetary system to ours and it would be really nice to know if there was life on Mars, to learn about it and to find out what happened to life on Mars.”

NASA planetary scientist Joel Levine has put forth a similar argument, maintaining that return to Mars “is the most likely target for life outside the Earth.”

The space agency has launched several missions aimed at mapping, gathering images of and monitoring conditions on the Red Planet. Data collected by the Mars Reconnaissance Orbiter, a spacecraft orbiting Mars, recently found evidence to suggest “possible flowing water during the warmest months on Mars,” according to NASA.

During Wednesday's event, which celebrated July's final space shuttle mission, Walheim and three other astronauts from the Atlantis mission also offered a glimpse into the more pedestrian aspects of life in space at the event.

Sesame Street’s Elmo, who interviewed the astronauts onstage as part of the event, asked the crew members to explain what they do with their toothpaste when they brush their teeth in zero gravity.

“In space you can’t just spit it into the sink because you don’t have a sink and that’d be really messy,” said mission specialist Sandy Magnus. “Some people like to spit into their towel and get rid of it that way. I found it was much easier just to swallow it and get rid of that way.”

Not all agreed, however: Magnus’ colleague chimed in, “I didn’t want to swallow toothpaste.”

Walheim reflected on how his over 800 hours in space had changed him, noting that the experience had given him new appreciation for the fragility of life on Earth.

“If you look at the rim of the Earth, the atmosphere of the earth, it only goes up 10 to 20 miles, and you realize that it’s only this tiny atmosphere that keeps us alive,” he said. “We’re all on this spaceship together. The Earth is a spaceship and there’s very little to keep us alive.”