NASA spacecraft revolving around and studying Mars have found the strongest indications of water flows on Mars while studying seasonal features.
Geophysical Research Letters
In a study by NASA’s Mars Opportunity Rover, it has been observed that water was present on Mars about four billion years ago that was probably supportive of life (DOI: 10.1126/science.1248097)
Now scientists have found some indications of water on Mars in certain seasonal features. These features are represented by dark, finger-like markings moving down some of the Martian slopes as the temperatures rise. These dark flows are called as “recurring slope lineae” (RSL).
New indications include relative seasonal changes in iron minerals on the same slopes, along with ground temperatures and some other related characteristics. This shows that brines with iron-mineral antifreeze, such as ferric sulfate, may represent seasonal flow. However, there could be other reasons.
“We still don’t have a smoking gun for existence of water in RSL, although we’re not sure how this process would take place without water,” said Lujendra Ojha, a graduate student at the Georgia Institute of Technology, Atlanta.
Ojha and Georgia Tech assistant professor James Wray 13 confirmed RSL sites using images from the same orbiter’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument. Although, they didn’t find markers of water or salts but they found markers of ferric and ferrous minerals.
Ojha said, “Just like the RSL themselves, the strength of the spectral signatures varies according to the seasons. They’re stronger when it’s warmer and less significant when it’s colder.”
One possible reason of these changes is the removal of fine dust from the surface that could occur due to either a wet process or dry one. Among other possible explanations are elevated ferric component of minerals, or moisture resulting in overall darkening. These reasons point to the presence of water though there is no direct observation.
“The flow of water, even briny water, anywhere on Mars today would be a major discovery, impacting our understanding of present climate change on Mars and possibly indicating potential habitats for life near the surface on modern Mars,” said Mars Reconnaissance Orbiter Project Scientist Richard Zurek, of NASA’s Jet Propulsion Laboratory, Pasadena, Calif.
NASA Mars Orbiters See Clues to Possible Water Flows – NASA (http://goo.gl/rJrup5)
R. E. Arvidson et al. (2014). Ancient Aqueous Environments at Endeavour Crater, Mars Science DOI: 10.1126/science.1248097