Occasionally it’s strange to see photos from the Curiosity Rover on Mars.  Some of them feel distinctly like home.  I can almost imagine a person walking by on the soft sand, through the pathway of rocks, and over the horizon, like a traveller navigating the desert.  The latest panorama of Mars gives me that feeling in spades. And yet, this rusty world has too thin an atmosphere to allow a human to breathe.  It has no water to drink, and intense radiation from the Sun that prevents life from blanketing its surface.  It is human, and yet alien.  No homo...