"Old Soaker" Gives New Evidence Of A Wet Mars

The NASA Curiosity rover investigated a rock in Mars dubbed "Old Soaker" that scientists believe may have formed from the drying of a mud layer more than 3 billion years ago. The view in the image looks like it was taken from a very high altitude, but it is a close up of a smaller piece of rock.

The image spans about 4-feet left to right and is a combination of three images taken by the Mars Hand Lens Imager (MAHLI) camera on the arm of the Curiosity Mars rover. The dried cracks in the surface of the rock are believed to be evidence of a time when dry intervals interrupted wetter periods that supported lakes in the area of Gale Crater.

When the MAHLI camera snapped the image, it was about 3 feet above the surface of the rock. The picture was snapped years ago on December 31, 2016. NASA says that the rock gives us an idea of what the surface of Mars might have been like 3.5 billion years ago. The team says that ponds dotted the floor of Gale Crater, and streams might have flowed down the walls of the crater.

The rocks are enriched by mineral solids discovered by the rover that give evidence of shallow briny ponds that went through episodes of overflow and drying. The scientists want to understand how long it took Mars to transition from the freezing desert known today from the wetter environment of the distant past.

The evidence of shallow briny lakes comes from salts found in the sedimentary rocks of "Sutton Island." The team says that when a lake dries up entirely, it leaves piles of pure salt crystals being. Salts discovered on Sutton Island are different, mainly they are mineral salts, not table salt. The team thinks that Sutton Island might have resembled the saline lakes on the South American Altiplano. In drier periods, those lakes get shallow and can dry completely, making them heavily influenced by climate just as Gale is.