March 29, 2013
Alaskan Sand Dunes Provide Possible Evidence Of A Watery Past On Mars
Lee Rannals for redOrbit.com — Your Universe Online
A unique find beneath frozen Alaskan sand dunes suggests that liquid water may still exist on the Red Planet.
Scientists from Southwest Research Institute (SwRI) performed field studies of the Great Kobuk Sand Dunes and found the presence of liquid water during Arctic winter there, suggesting that liquid water could be temporarily stable at frost-covered sand dunes on Mars.
They conducted fieldwork in Kobuk Valley National Park, Alaska, when the average daily surface temperature was 5.5 degrees Fahrenheit. Data gathered by the scientists suggest there is a perched layer of liquid water in the dunes occurring just below the frozen active layer.
The team also noticed that several melt-water debris flows formed on sunward-facing dune slopes. At one location, ground surface temperature measured nearby was within a few degrees Fahrenheit of the thaw point for fewer than 10 minutes.
An even colder period at another dune location showed ground surface temperatures measured near active debris flows never approached the thaw point. The team believes that patches of dark sand on bright white snow enabled highly localized thawing.
"Debris flows with gully or erosion tracks also appear on the slopes of several dune fields on Mars. Very few minutes of above-freezing temperatures are needed to locally melt water and mobilize sand transport down steep slopes," hydrogeologist Dr. Cynthia Dinwiddie, a principal engineer in SwRI's Geosciences and Engineering Division, said in a statement.
She said that this phenomena occurs at a temperature corresponding to those that had been seen before on the surface of Mars.
"Recent measurements of air temperature and pressure recorded by the Mars Science Laboratory on the Curiosity Rover, which landed in Gale Crater last August, suggest that liquid water potentially would be stable there during the warmest portion of each day," said Dinwiddie.
The triple point of water is when liquid water, solid ice and water vapor are able to coexist in stable equilibrium. Dinwiddie says environmental conditions at the Great Kobuk Sand Dunes during late-winter to early-spring are similar to those on Mars, which means that these dunes can serve as an informative guide as to what to expect on the Red Planet.
Scientists are pretty sure that Mars had ancient river beds and water in its past. NASA's Curiosity even found some evidence for these claims in a recent drilling. The Mars rover was able to sniff out the presence of sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon from the rock sample. When the sample was heated to 1,535 degrees Fahrenheit, it showed the presence of water, carbon dioxide, oxygen, sulfur dioxide and hydrogen sulfide.
Curiosity is on a mission to determine whether Mars ever had conditions favorable for ancient life on Mars. The rover will be taking a vacation as the Sun interrupts transmissions between the Red Planet and Earth starting in April.