From a mathematical standpoint, it’s highly unlikely humans are alone in the universe. With so many star systems with planets in the “habitable zone” (many of which we’ve yet to discover), the idea of Earth being the sole life-bearing planet is statistically less likely. Though seemingly a pipe dream for many, NASA’s Chief Scientist Ellen Stofan thinks were much closer to finding signs of life than many would think – maybe as soon as the next decade.
“I believe we are going to have strong indications of life beyond Earth in the next decade and definitive evidence in the next 10 to 20 years,” Ellen Stofan, chief scientist for NASA, said at a public panel, which was life streamed Tuesday from Washington.
Of course, don’t get your hopes up for transmission from E.T. The scientists are talking about small life forms, like bacteria and other microbes. The signs, they say, maybe right under our noses. They cited the atmosphere above Mars’ ice caps, which show evidence that the planet was once 50% covered by oceans up to a mile deep, oceans that existed for a long time (over one billion years), they say. If conditions were right with that much water around, it would almost be stranger for life not to develop.
Another recent study found that Jupiter’s moon Ganymede actually has a robust liquid ocean hiding beneath its icy exterior. These studies have changed the way scientists think about “habitable zones,” which describe places where the temperature is mild enough to support life. Though typically only considered in relation to stars and planet, large planets and their moons may have their own kind of habitable continuum. Europa, another of Jupiter’s moons, also appears to have liquid oceans.
“We are finding out the solar system is really a soggy place,” said Jim Green, director of planetary science at NASA.
Of course, NASA isn’t limited to looking for life in our own solar systems. Future telescopes will be better able to help scientists analyze the atmosphere of distant rocky planets, according to Paul Hertz, director of astrophysics at NASA. Within the atmospheres of planets in their systems’ habitable zones, scientists would hope to find chemical markers indicating the possibility of life.
Even if we found E.T. (or perhaps his microbial ancestors), it’s unlikely alien life would look anything like the life we see on Earth.
“Once we get beyond Mars, which formed from the same stuff as Earth, the likelihood that life is similar to what we find on this planet is very low,” said NASA associate administrator John Grunsfeld