Seasonal changes can have a dramatic effect on how quickly Mars loses its water to space, a joint study between the Hubble Space Telescope and NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission has shown.

Over three billion years ago, Mars was warm and wet, with large bodies of water on its surface and a thicker atmosphere. Today, however, Mars is desolate, cold and dry. So, what happened to all the water?

"There's only two places water can go," John Clarke of the University of Boston said in a statement. "It can freeze into the ground, or the water molecules can break into atoms, and the atoms can escape from the top of the atmosphere into space."