Scientists just found the best evidence yet that liquid water is currently present on Mars. Using data collected by the Curiosity rover, they determined that tiny amounts of water vapor condense as a liquid in the planet's soil at night and evaporate away in the morning. The research, published today in Nature Geoscience, shows that high amounts of salt in the soil lower the melting point of water, allowing it to temporarily pool as a liquid despite the subzero temperatures. http://www.vox.com/2015/4/13/8384337/mars-water-liquid-curiosity