24th January 2014 Sol 522

The Science Magazine papers about Yellowknife Bay have just been published:

http://www.sciencemag.org/content/current

Looking back at this work what strikes me is how far Mars research has progressed in the last few years.  As I was saying at  talk at a local community college last night, our view of Mars keeps changing as our imaging improves.  If I had given the talk 100 years ago, I would have discussed the pros and cons of Percival Lowell’s canals theories.  In the 1940’s I would have discussed the evdience for vegetation on Mars causing seasonal changes in the albedo of the planet.  In 1964, the first Mariner 4 flyby produced grainy images with indistinct craters – were they volcanic or impact in origin?  Even just 10-15 years ago in an equivalent talk I would have been debating whether the metre-scale layers that were being identified by orbital imagers were volcanic or sedimentary in origin. 

In the Peace Vallis conglomerates and Yellowknife Bay mudstones we have unequivocable proof for a habitable environment, with near neutral pH, brackish pore water heated to around 50 ^oC, fine for any microbes.  But were there ever any microbes on Mars? That part of the puzzle remains to be determined.