Mars According to planetary scientists, salt water pools may still exist on Mars, just below the surface of the planet. It has been previously thought that any remaining water on Mars must exist solely as either ice or vapour due to the low pressure and temperature.

Nasa's most recent Mars probe, the Phoenix Lander has found the presence of perchlorate salts, which can keep water in its liquid form at temperatures of minus 70C. It is currently believed that the pockets of salt water may form when this soil interacts with ice.

Pheonix first landed on the red planet on the 25th May 2008, using thrusters to slow it's decent. These thrusters blew away the top layer surface and exposed ice hidden just centimetres beneath the surface.

This enabled the Mars Lander to sample the ice directly, however also found a few centimetres above the ice was the perchlorates. These perchlorates are salts derived from perchloric acid and back on planet earth they are used in solid rocket fuel, fireworks and airbags.

While many researchers are cautious over the volume of Percolate salt in the ground, it is encouraging that in one more way, Mars is similarities to Earth.