It's possible that the civilization on Mars is a quantum dimensional shift from our current frequency of vibration, several micro-oscillations out of sync so that we don't have direct evidence of it. When we finally can launch the Bradbury Rover, it will have a detector on board that will view in various frequencies, and THEN we'll REALly see something.
Ron Miller — Martian City — digital art
In the meantime, wishing the very best of fortune to the Curiosity and it's Earth team during it's seven minutes of terror. I'll be watching and hopefully you will too— on NASA TV.