Intriguing and often-examined gullies on Mars might not be created by water seeping out from underground springs, according to a new study. Rather, they are likely caused by trickling water from melting snowpacks, an active process that could sustain biology on the Red Planet. A leading Mars scientist has proposed a new theory regarding gully formation on the planet, backed by images taken from NASA’s Mars Odyssey spacecraft. The research bolsters the view that liquid water is sheltered by snow, preventing the fluid from rapid evaporation in Mars’ thin atmosphere.