At some point we’re going to have to decide that we’re done studying a “pristine” Mars and that we want to transform it. Bio-engineered bacteria will be the way. We probably need to take a kitchen sink approach and engineer something that eats iron oxides and spews CO2 or Oxygen. We’ll also need something that eats perchlorate too. And then we just fly drones all around the planet dumping it out. We probably want to drop lots of activates carbon all over the poles to make them warmer.

I’m sure there will be quicker and easier terraforming methods in the future but we’re not there yet and if we never get there, these could at least make Mars less inhospitable.