MARS LEAKS FASTER WHEN IT'S CLOSER TO THE SUN

The Red Planet has lost enough water to space to form a global ocean hundreds of kilometres deep

- Keith Cooper

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 3 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? Plenty of Mars' water is still on the Red Planet. Vast reservoirs appear to be locked up deep underground at depths between 11.5 and 20 kilometres (7.1 and 12.4 miles). There's enough water inside Mars for a global equivalent layer (GEL), which essentially refers to how deep a planet-wide ocean it would create, between one and two kilometres (0.62 and 1.24 miles). Relatively small amounts of water-ice are also locked up in shallow permafrost and in Mars' polar