When a Mars rover leaves a trail of tracks in the Martian dunes, is it a tragic imprint of human intrusion on a pristine alien landscape billions of years old, or the first hopeful sign of intelligent life arriving on a long-dead planet?
When a Mars rover leaves a trail of tracks in the Martian dunes, is it a tragic imprint of human intrusion on a pristine alien landscape billions of years old, or the first hopeful sign of intelligent life arriving on a long-dead planet?