Free Astronomy Magazine November-December 2015

NOVEMBER-DECEMBER 2015 5 PLANETOLOGY That in a more or less re- mote past Mars hosted li- quid water is well known for some time. But only a hydrological system that is still active today could sup- port any form of indige- nous life and facilitate the exploration of the planet by terrestrial “aliens”. Now we have the certainty that, although sparingly, water really flows up there. there ter S pectacular series of Recurring Slope Lineae active inside Acheron Fossae. Researchers have confirmed that at the origin of these structures there is the movement of briny water. [NASA/JPL-Caltech/Univ. of Arizona] T he existence of water on Mars is a topic that has fascinates mankind for more than a century. In the last fif- teen years, what had been just a hypothe- sis has increasingly become a concrete re- ality. Crucial in this regard has been the NASA’s Phoenix mission, which in 2008 confirmed the presence of water ice in the Martian soil. Even more significant was then the discovery made in 2012 by Curi- osity rover, which photographed the beds of ancient streams. What was missing, though, was the next step, namely the evidence that even today water still flows on the surface of the red planet. That this was possible was already known for many years, due to the pres- ence of traces of geologically very recent