Rocks from Water

Photo Credit: Nasa

  On the left, a Martian rock formed in highly acidic water (photographed by Opportunity) and, on the right, one formed in very neutral water (from Curiousity). The one on the right, unlike the one on the left, belonged to an environment of relatively fresh water with chemical gradients that would have been conducive to the metabolism of microorganisms.

  Abundant warm wet environments persisted on Mars from (very) roughly 4.5 to 3.0 billion years ago (and water persisted on the surface even as the planet started to dry for another billion years or so). Within the same time span, Earth had abundant primitive life.

  Being smaller, and thereby cooling faster, Mars probably even had some hundreds of millions of years on Earth to harbor life first. I'd be fairly surprised if we found fossils of very complex life on Mars, but I'd be equally surprised if there weren't evidence of very primitive life hiding away in its most ancient rock formations.

  Honestly, I think there's a good chance Gale Crater itself might have a surprise in store for us.

  For more information, check out the source link:
  http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA16833