WATER ON MARS

1 Dry soil

Martian soil forms a dusty layer, made up of nutrients such as sodium, potassium, chloride and magnesium.

2 Signs of ice

Surface ice is thought to have become buried, leaving a permafrost subsurface with young ice in its pores.

3 Pockets of water

Water ice is locked within cavities across the mid-latitudes of the planet.

4 Subsurface reservoirs

Underground lakes are thought to exist far beneath the surface of Mars, locked under land.

5 The foundation

Water would lie above an impermeable bedrock that has a high concentration of sulphur.