We'll Find Alien Life Within 20 Years, NASA Says

Jupiter's icy moon, Europa almost certainly has liquid oceans that rest upon mineral-containing rocks, according to NASA. NASA/JPL-Caltech/SETI Institue/Handout via Reuters

Is there life on other planets? People have pondered this question for millennia, without any definitive answer. But now, NASA officials say, we may soon be on the cusp of a breakthrough.

"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 Tuesday in Washington, according to the Los Angeles Times.

"It's definitely not an if, it's a when," said Jeffery Newmark, one of Stofan's colleagues.

One of the reasons the agency is so confident: Water—considered to be necessary for life—keeps turning up in more and more places. Peering through telescopes, scientists have found it in asteroids, dwarf planets like Ceres, giant clouds between stars and on many of the planets in our solar system.(Scientists now believe that Jupiter, Saturn, Uranus and Neptune all contain water in their interior and/or atmospheres). There is also strong evidence that water is present on the five icy moons of Jupiter and Saturn: Jupiter's Ganymede, Europa and Callisto, and Saturn's satellites Enceladus and Titan.

Enceladus and Europa almost certainly have liquid oceans that rest upon mineral-containing rocks, according to various measurements made by spacecrafts and telescopes, and both are geologically active, the agency noted in a release. These bodies have the three components which astrobiologists think are necessary for the development of life: water, a source of energy (e.g., volcanic activity) and chemicals used in biological processes, potentially including nucleic acids. Data from NASA's Hubble Space Telescope also recently suggested that Ganymede has a saltwater ocean.

Researchers have also found water in the polar ice caps of Mars, and the planet likely once had a liquid ocean. Ice has even been recorded on the moon and Mercury.

Scientists aren't expecting to find little green men or whatever those aliens were in Independence Day, but rather microbes, according to Stofan. That said, a recent paper estimated that if intelligent beings exist, they are likely to be much larger than humans.