At the PBS NewsHour site, space journalist Miles O'Brien recounts the history of human exploration of the red planet, leading up to this Sunday's planned landing by the Mars Science Laboratory rover Curiosity. It's gonna be a nail-biter. Snip:
Ralph Harvey is a professor of planetary minerals at Case University. He spends a lot of time looking for Mars meteors in Antarctica. He has not yet seen anything that says "life" to him:
"When we argue about signs of possible life on Mars it's always the most subtle thing you can imagine," he told me a few years ago. "Something at the very edge of measurability, and life did not proceed that way on earth. Life is in your face. Life is something we have to scrape off the rocks to get to the story of the rocks. And I don't see that on Mars. I don't have that sense about Mars. So life on Mars is going to have to get in my face for me to believe it."
But what if life on Mars is hiding deep beneath the surface -- say in an underground aquifer? Could there be an underground habitable zone on Mars today?