Antarctic Pond Gives Potential Evidence of Water on Mars

A pond in Antarctica's McMurdo Dry Valleys never freezes, despite the frigid temperatures. There's a reason, though. The pond, named the Don Juan Pond, is the saltiest natural body of water on Earth. Now, researchers have found out exactly how this pond became so salty, and how their findings could have implications for the possibility of similar bodies of water on Mars.

The findings, published online in Scientific Reports, used timed lapse photography and other data in order to determine where the pond got its salt. The research team installed a camera above the Don Juan Pond and took a total of 16,000 images in two months. This helped document the geological processes in real time.

The researchers found that the water sucked out of the atmosphere by parched, salty soil is the source of the saltwater brine that keeps the pond from freezing, despite being in one of the coldest and driest places on Earth. In addition, some fresh water flows in from melting snow, which allows the pond to maintain its liquid form and not completely dry out.

Researchers saw that water levels in the pond increase in pulses that coincide with daily peaks in temperature. However, the influx of fresh water doesn't explain the high salt content, which is eight times greater than that of the Dead Sea. A channel of loose sediment to the west of the pond seemed to be the ultimate cause. Dark streaks of moisture called water tracks formed in the soil whenever the relative humidity in the air spiked. Essentially, the salt in the area was absorbing any moisture in the air and trickling into the pond.

More interesting, though, is the idea that this study could have major implications for Mars. The images of water tracks at the pond look quite a bit like features recently imaged on Mars called recurring slope lineae--dark streaks the seem to flow downslope on cliff faces. This could point to the possibility that there may indeed be flowing water on present day Mars.