Watch: Is there life on Mars? Possibly.
NASA's Curiosity rover discovers ancient lake bed on Mars.
The scientists conducting Curiosity's mission to Mars believe that a 96 mile wide crater on Mars may be all that remains of an ancient lake.
Since Curiosity landed on Mars in August 2012 the probe has been gathering evidence of the existence of water on the surface of the red planet at some point in its distant past.
Travelling around its touchdown point of Gale Crater the robotic science lab has discovered numerous clues that point to an aquatic ancestry.
Its findings include piles of rocks which contain what scientists believe are water deposited sediments which rise towards Mount Sharp, a three mile high mountain at the centre of Gale crater.
These sedimentary layers, known as "inclined strata" take millions of years to build up, and are thought to have been created around 3.5 billion years ago in what was a warm wet period for Mars.
This period is thought to have contained the right conditions for the formation of basic microbial life if these conditions last for long enough.
Judging by the size of the lake's crater, and the amount of sedimentary deposits within, that appears to have been a possibility.
However, scientists are unsure as to whether or not there would have been dry spells which could interrupt this life-building process, and how long the conditions need to be prevalent for life to occur.
By careful study of sedimentary geology though, scientists are quite sure there was not only a lake but "a system of alluvial fans, deltas and lakes and dry deserts that alternated for millions, if not tens of millions, of years as a connected system," according to Curiosity project scientist John Grotzinger.
Curiosity has discovered rocks which contain banding similar to those found on earth when silt and sediment slowly falls through a body of water and settles, and crystals which appear to be salt-deposits which remain after water has evaporated.
So while Mars may be a barren and inhospitable place now, the red planet may once have been a blue planet.