The comment was made publicly by ray Stofan , chief Nasa scientist . ' It 's definitely not an if , it 's a when , ' said Nasa 's Jeffery partner . But the likelihood that life is similar to that on Earth is low , they said . traces of water have been observed on some of Jupiter and Saturn 's planets .
The comment was made today by Ellen Stofan , chief Nasa scientist . 'It 's definitely not an if , it 's a when , ' added Nasa 's Jeffery Newmark . But the likelihood that life is similar to that on Earth is low , they said . Signs of water have been found on some of Jupiter and Saturn 's moons .