NASA chief scientist Ellen Stofan said the first signs of alien life could be discovered by 2025, and additional evidence will be revealed in 20 to 30 years.
Even if humans aren't alone in the universe, don't expect aliens from Hollywood films, as it's more likely researchers will find "little microbes."
"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," Stofan recently said during a panel discussion. "We know where to look. We know how to look. 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 and international space agencies have been on a constant hunt looking for water, finding oceans of liquid water on Jupiter moons Europa and Ganymede. NASA has also found signs of water on Saturn's moon Enceladus, while there have been numerous traces of ancient water on Mars.