we know without any question that there was volcanism on the surface of mars and, in fact, the largest volcano in our solar system exists at olympus mons, which is a volcano so high that the peak actually pierces through the atmosphere of mars. wow. yeah. and in the whole area of the basin around the volcano — olympus mons — it is believed there are certainly lava tubes. here's something else that's really exciting about this lava tube. now, mars is red because there is a lot of iron in the rocks. and that white glistening stuff there, that is icelandic cave bacteria. it doesn't need any light to live. it can survive in near—freezing temperature. it just feeds off the iron and the sulphur in the rocks down here, away