NASA is all a-twitter due to some new images gathered that show “dark, finger-like features” that “appear and extend down some Martian slopes during late spring through summer, fade in winter, and return during the next spring.” That the features recur every cycle-through of the seasons indicate that they are not merely anomalies, but rather something like the swelling of streamlets and rivers here on Earth from thawed snow and ice.
Any liquid water to be found on Mars would most likely be very salty or “briny,” though, according to NASA. Based on what is known at this point of the surface chemistry of Mars, any water to be found on the surface would have a sodium concentration comparable to our own oceans. This lowers the freezing point of the water, making it possible for it to exist in a liquid form in Mars’ sometimes lower surface temperatures.
There are also markings in the soil and rock that are indicative of flowing water.
NASA astronomers are not 100% certain about the find as of this point, however. Spectroscopy scans made by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) do not reveal any liquid water. According to Alfred McEwen of the University of Arizona, Tucson, “the flows are not dark because of being wet…they are dark for some other reason.” The flows he was referring to were the lines in the soil and rock, and the dark lines seen by the Reconnaissance Orbiter. If the ground is completely dry and does not have little streams of brine in it, then it becomes a new mystery that it would lighten just in those areas during the winter.According to NASA, this is the closest they have ever come to finding liquid water on Mars, and makes it an even more ideal place to visit by astronauts for study.