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Why Humanity’s Survival May Depend on Colonizing Mars

Mars Water 101: What's New in the New Discovery 1:01

After decades of space exploration and countless movies on the subject, why exactly does Mars continue to inspire such high levels of cultural and scientific fascination?

Both the red planet and NASA are coasting on a wave of newfound popularity, taking center stage in big-budget Hollywood productions. Whether by coincidence or design, the favorable treatment of NASA by Tinseltown comes at a time when the space agency recently discovered evidence for flowing water on Mars, and last week openly declared colonizing the planet within the next 20 years "an achievable goal." And at least a few scientists think the survival of humanity may hinge on finding a new, hospitable planet to colonize.

Just a few years ago, NASA critics and even some supporters were openly questioning whether the Mars science laboratory was worth its $2.5 billion price tag.

Fast forward a few years, and the space agency is moving full speed toward establishing a human presence on the planet — a quest that looks less and less quixotic by the day.

Read More from CNBC: Evidence Found of 'Flowing Liquid Water' on Mars: NASA

"Mars is obviously the logical next place to expand our capabilities and getting Earth crews there," Edwin "Buzz" Aldrin told CNBC in a recent interview. The famed astronaut and second man to walk on the moon's surface said sending humans to the planet would be an accomplishment "that's unparalleled in humanity."

In a document outlining its rationale for sending humans to the far-flung planet — which lies 140 million miles from the Earth — NASA invoked the 1969 Apollo voyage, adding that unlike the moon, a mission to Mars would involve "going to stay."

Mars' atmosphere is noted for its thin, carbon dioxide-filled air and ferocious dust storms that last for months. But given the right conditions, some think Mars could eventually be capable of sustaining humans.

"We need to keep public interest stimulated and demonstrate to our leaders ... this is a most historical opportunity," Aldrin said, speaking from a conference in Israel. He added the human race was in a prime position to become "pilgrims in setting up permanence on Mars."

In fact, the prospect of humans pioneering on Mars is gradually becoming more and more of a reality — and in some ways may be a necessity, a top-ranking NASA scientist told CNBC recently.

"If the human species is going to survive, is it going to survive solely on Earth or not," asked Jim Greene, NASA's director of planetary science. "The appeal has been that as we explore, the next frontier beyond our atmosphere is Mars. That captures a lot of imagination in science, but also in science fiction."

Yet Greene also underscored the inherent dangers of outer space, and the imperative to discover other systems capable of sustaining human life.

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He characterized Earth as existing in "a dangerous part of the solar system" that runs the outside risk of being hit by a "planet-killing" asteroid. Although it may sound like a plot from a science fiction movie, Greene explained that NASA has identified 876 out of more than 12,000 near-Earth objects that the agency is "really monitoring carefully."

Is Water Discovered on Mars Evidence of Extraterrestrial Life? 2:05

"In the last 500 million years of the Earth's history there have been five mass extinctions of species. The last one was the end of the dinosaurs," Greene said, referencing the event that scientists surmise brought about the extinction of dinosaurs more than 65 million years ago.

Within the known range of potential "planet killers" — asteroids that are at least 2 km in size — that the space agency monitors, "there are more than 150 that we're really watching carefully," Greene said. These "potentially hazardous asteroids" will come within 5 million miles of the planet over the next 100 years.

“They cross our orbit frequently, and we know we're going to get hit again," Greene said. "It’s not a matter of if, but when."

Within the last several decades, there have been minor brushes with asteroids, but none that have the potential to endanger human life on a large scale — at least not yet.

Recently, NASA disclosed it was monitoring a 480-meter asteroid that could collide with the Earth sometime within the next four decades. British astronomers have been even more stark in speaking of the likelihood that a space rock of large enough size could create pandemonium around the world.

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Asteroids "cross our orbit frequently, and we know we're going to get hit again," Greene said, underscoring that factors such as trajectory and conditions in space can determine whether asteroids hit the earth or pass it by.

However, "it's not a matter of if, but when. This planet won't have a planet killer hit it for many hundreds of years, but it will happen," he added.

The panoply of risks makes it important to seek out viable alternatives to ensure humanity's survival. Likening the idea of an extraterrestrial colony to a computer's external hard drive, Greene told CNBC that "If we're going to live as a species, we're going to have to 'back up' in other places ... and that place is Mars."