Evidence of Water on Mars Is Drying Up
Image credit: NASA/JPL
Scientists have long suspected that subsurface water may still be flowing on Mars, but a new study suggests that evidence of water on the Red Planet might be nothing more than the movement of sand and dust.
Observers of Mars have a long history of seeing things that seem like clues to life, only to have the Red Planet slap such hopes down. As early as 1906, when astronomer Percival Lowell "determined" that there was life on Mars, the planet has served as mankind's closest hope for a host of extraterrestrial organisms. Unfortunately, conclusive evidence always seems to prove false or inconclusive.
Now the suggestion that water may be flowing under the Martian sand has been dealt a blow by a study published Monday by research team made up of representatives from the Department of Earth Sciences of Durham University (UK), the Planetary Science Institute and University of Arizona, Lunar and Planetary Laboratory in Tucson, and the US Geological Survey, Astrogeology Science Center in Flagstaff, AZ. Inspired by recurring slope lineae (RSL), it suggests that while RSLs are "candidate locations for seeping liquid water on Mars today…their formation mechanism remains unclear."
Researchers added that "warm seasons and the detection of hydrated salts are consistent with some role for water," when it comes to the lineae, but they suggest that topographical analysis demonstrates "that the terminal slopes of recurring slope lineae match the stopping angle for granular flows of cohesionless sand in active Martian aeolian dunes," and that some of the RSLs are "inconsistent with models for water sources. These observations suggest that recurring slope lineae are granular flows."
Specializing in granular physics and fluid dynamics, the research of Durham University Professor of Geohazards Jim McElwaine suggests sand grains are a strong culprit behind the Martian RSLs.
"I have shown experimentally in the lab that if grains are slowly deposited on a uniform slope there will be small avalanches with no specific cause," McElwaine said. "These will move down between the same levees and extend the deposit pattern before stopping."
The study's lead author Colin Dundas, a USGS research geologist, says that while it's been previously thought that RSLs may represent possible liquid water flows, "the slopes are more like what we expect for dry sand."