Have you already planned where to go on holidays this summer? How about Mars? Quaid may drop a hint or two on this destination for you: In fact, people started theorizing quite early about the possibility of Mars being habitable. The first one would be Schiaparelli, at the Milan Observatory (1877), who observed that the whole of the tropical and temperate regions from 60° N. to 60° S. Lat. in Mars were covered with a remarkable network of broader curved and narrower straight lines of a dark color. These formations were called Canals and, at the time, believed to be artificial. Furthermore, Mr. W. H. Pickering discovered in 1892 that these canals intersected by means of some circular black spots. By the time, observations of color changes led (optimistic) people to believe that canals were in fact used for irrigation. It wasn’t until 1894 that astronomers started to put in doubt the existence of water in Mars. It was at this point (1911) that Edgar Rice Burroughs wrote his well known John Carter series, where Mars was inhabited by at least three different races of martians, with canals, buildings, palaces and flying machines, too. And, of course, one could walk the surface without a suit. Gee, gotta love this guy’s books! Whereas McMillan’s Man’s Place in the Universe (1902) happily claimed that Mars had a weather similar to the south of England, Lowell’s book, Mars and its Canals (1907) made a (detailed) point on how a thinner atmosphere, and the consequent harsh temperatures made it impossible for the Red Planet to support life, putting special emphasis on the lack of water evidence on the surface. Since then, the main issue to support that Mars has never been habitable, as portrayed in Total Recall, has always been the lack of evidence of water on its surface. However, the arrival of rovers to our neighbor planet actually allowed us to go beyond the surface, right? Since its arrival to Mars, the Curiousity rover have been roaming around and drilling here and there to gather rock and ground samples. And last march, it hit jackpot.
While drilling at Yellowknife Bay, Curiosity found both clays and sulfate minerals, materials that only form in water, and only in water that is low in potentially life-killing acids. Given that Mars was once much wetter and warmer, and that there are minerals that can be formed only in the kind of water that can support life, the probability of organic life there is not a total zero anymore. It is important to hit the brakes, though: although life would have been possible in theory, there are absolutely no signs of past inhabitants in Mars (thus far :D). The next big question here is, obviously, if we could make Mars habitable: terraforming has always been a big part of scifi. Apparently, scientists say yes, but don’t get your hopes too high, you’re not having a holiday in Mars anytime soon. It seems that rovers have found some organics in the planet, most likely unwillingly brought there by the previous robot. However, findings show that it is entirely possible there is microbial life on Mars now.