There is also a seasonal pattern to terrestrial life that many organisms have adapted to that would be different on any other planet. Bottomline...from the standpoint of life....Mars is basically a dead planet. My point is that---despite this---it is the most Earth-like of all the other Inner Planets. So the Traveller would have to perform the fewest "miracles" on it, in order to terraform it. What the Traveller did to Venus and our Moon bent the laws of physics until they screamed. What It did to Mercury just took them, and set them on fire.....