Mars ain’t the kind of place to raise your kids. In fact it’s cold as hell.
Elton John, “Rocket Man” (1972)

Unquestionably, Mars was a habitable planet in its ancient past.
John P. Grotzinger, NASA Mars Project Scientist (2013)

Reading an article in the N.Y. Times science section recently about NASA’s Mars rover project, I was struck by Mr. Grotzinger’s quote.  “Unquestionably” Mars was habitable in the distant past?  I had not realized this had been definitively established, or even that it was likely.  Evidently, it is now beyond question.

We earthlings have long been intrigued by the possibility of life on Mars.  I went through a space-geek phase as a kid and was particularly fascinated by Mars.

While driving to the Wild Goose Festival we were listening to podcasts and I heard Krista Tippett’s fascinating interview of geomorphologist David Montgomery.  In it, he mentioned the discovery that Martian topography reveals evidence of enormous floods.  I had Mr. Grotzinger’s comment on my mind when I heard the podcast and was surprised to so soon be confronted with another statement about the Martian past.

So if Mars was once a habitable planet, with so much water that it dramatically altered the topography of the planet, how did it become the barren, dry place that it is now?  Why did it cease to be habitable?  Whatever the cause, is it reversible?

Most significantly, when Mars was habitable, was it inhabited?

Inquiring minds want to know…