These 4 Places in the Solar System are Likely to Have Alien Life – NASA Director

A NASA director surveys which places in the solar system are most likely to harbor alien life.

James Green, director of NASA's planetary science who leads the solar system exploration and astrobiology research, points to four places in the solar system that may have alien life. These are the planet Mars and the three moons of the outer planets: Titan, Europa and Enceladus.

Green presented his ideas at TedTalks Live in November last year. His talk was just recently uploaded to Ted.com, where he details why NASA believes they are on the brink of answering the perennial question of whether or not there is life beyond Earth and where in the solar system alien life is likely to live.

"I have to tell you that early in my career when we looked at these three elements, I didn't believe that they were beyond Earth for any length of time and in any real quantity," Green said during his talk. "Venus is way too hot-it's got no water. Mars is dry and arid-it's got no water. And beyond Mars, the water in the solar system is all frozen."

According to Green, the key is to look first for "ingredients of life," which are liquid water, energy and organic material. Having these elements present for long periods of time could make life "spark, and then grow and evolve."

Recent observations had steered NASA to the right directions to explore the possibility of life beyond planet Earth. Based on the life ingredients, astronomers focused their attention on the four places - Mars and the three moons.

Life on Mars

NASA had started a series of Mars missions to see if water existed on the planet in the past. The Curiosity rover had shown evidence that ancient Mars once held liquid water, and that there was a point in time when Mars's atmosphere may have contained enough oxygen, with the discovery of manganese oxides on the planet.

"It tells us that Mars has all the ingredients necessary for life," Green said. "So what are we going to do next? We're going to launch a series of missions to begin that search for life on Mars. And now it's more appealing than ever before."

Water on the Moon?

The Cassini spacecraft had revealed that Saturn's moon Enceladus has been blasting sheets of water out into the solar system and back down to its surface. Scientists also pointed the similarities between Enceladus and the Earth's "Lost City," because of the water plumes that are similar with the hydrothermal vents in the Atlantic Ocean.

Jupiter's moon Europa also spewed water from its cracks, as observed by the Hubble telescope. A recent study also found that Europa's rocky exterior might be more Earth-like than what was previously thought.

Lastly, Saturn's giant moon Titan was found to have an extensive atmosphere that is composed of nitrogen with a little methane and ethane. Also recently, NASA discussed its plan to send a submarine to Titan to look for signs of life on Titan's methane waters.

So is there really life beyond Earth in the solar system?

"We don't know yet, but we're hot on the pursuit," Green said. "The data that we're receiving is really exciting and telling us - forcing us to think about this in new and exciting ways. I believe we're on the right track. That in the next 10 years, we will answer the question."