Now these astonishing new images - captured by a European spacecraft in orbit around Mars - are helping to fuel that fascination. They show in astonishing detail a network of giant valleys, vast plains and towering waterfalls carved into the surface of our neighbouring planet, millions of miles away.
And while Mars today appears lifeless and parched, they are a reminder of how its surface was shaped by fast flowing streams, rivers and oceans. The pictures were captured by the European Space Agency's Mars Express Probe - a spacecraft the size of a large fridge-freezer that has been circling Mars since Christmas 2003.
