(CNN)They may not be "Star Trek"-type extraterrestrials, but we may be close to finding evidence of alien life, a NASA scientist says. "I think we're going to have strong indications of life beyond Earth within a decade, and I think we're going to have definitive evidence within 20 to 30 years," NASA chief scientist Ellen Stofan said Tuesday during a panel discussion on water in the universe. "We know where to look. We know how to look," she said. "In most cases, we have the technology, and we're on a path to implementing it. And so I think we're definitely on the road." NASA released a graphic noting that scientists have found evidence or indications of water on a number of celestial bodies, including the dwarf planet Ceres and Jupiter's moon Europa. The Hubble Space Telescope has been key to the discoveries, NASA said in a news release. "Scientists using NASA's Hubble Space Telescope recently provided powerful evidence that (Jupiter's moon) Ganymede has a saltwater, sub-surface ocean, likely sandwiched between two layers of ice," the agency noted. There are some caveats involved, of course. NASA isn't talking about intelligent alien civilizations from the Alpha Quadrant; it's referring to microorganisms. "We are not talking about little green men," Stofan said at the panel. "We are talking about little microbes." Still, former astronaut John Grunsfeld said it's an exciting time -- and he thinks it's just a matter of time before we find life outside our solar system as well. "I think we're one generation away in our solar system, whether it's on an icy moon or on Mars, and one generation on a planet around a nearby star," he said. And, he added, who knows what that life will look like? "Once we get out beyond Mars, the likelihood that it's similar to Earth because we share that material gets very, very low," he said. "And I think that's where it starts getting exceptionally exciting."
NASA chief scientist Ellen Stofan believes we're close to finding alien life . Indications within a decade; definitive evidence within "20 to 30 years," she said . Finding water on other celestial bodies is key to determination .