article_snippet.sent: habitability will examine habitability through time.
article_snippet.sent: Jeffery Newmark, interim director of heliophysics at the agency, added: 'It's definitely not an if, it's a when.' '
article_snippet.sent: We think that long period of time is necessary for life to get more complex,' Stofan said.
article_snippet.sent: I think we're one generation away in we solar system, whether one generation's on an icy moon or on Mars, and one generation [away] on a planet around a nearby star.
article_snippet.sent: At the same conference last year, Nasa Administrator Charles Bolden made a more conservative estimate.