The question of whether life ever existed on Mars has inspired scientists – and songwriters – for decades. The Red Planet is currently an arid, icy desert where no sign of life remains, but was it always this way?
It is widely recognised that living entities have three basic requirements: standing water, an energy source and the five chemical elements, carbon, oxygen, hydrogen, phosphorus and nitrogen. Then a very long time for the chemical soup to stew. The rover Curiosity has found evidence of all three in certain areas of Mars, namely the Gale Crater, but were these available for long enough for life to develop?