Ancient Mars once hosted habitable environments with liquid water, scientists find evidence

Mars once hosted habitable environments with liquid water, according to scientists who have found evidence for widespread buried deposits of iron- and calcium-rich carbonates on the red planet. “Identification of these ancient carbonates and clays on Mars represents a window into history when the climate on Mars was very different from the cold and dry desert of today,” Janice Bishop of the SETI Institute in the US said.

The environment on Mars was warmer and wetter, suggests the Carbonates beneath the surface of the red planet. The emergence of life on Mars could have been fostered by the presence of liquid water. Scientists have been debating energetically about the fate of water on Mars because the red planet is currently dry and cold. This is in contrast the widespread fluvial features that etch much of its surface.

According to scientists the bedrock of Mars should be full of carbonates and clays if water did once flow on its surface. This would be evidence that Mars once hosted habitable environments with liquid water.

Finding the physical evidence for carbonate-rich bedrock has been a struggle for researchers. The trapping of carbon dioxide in Mars’ early atmosphere in ancient surface waters may have resulted in the formation of carbonate-rich bedrock. The researchers are focussing their search on the Huygens basin of Mars.

According to researchers, in order to study carbonates, this feature is an ideal site. The reason is that the ancient, subsurface materials have been exposed by multiple impact craters and troughs. There carbonates  can be detected across a broad region, they said.

“Outcrops in the 450-km wide Huygens basin contain both clay minerals and iron- or calcium-rich carbonate-bearing rocks,” said James Wray, from the the Georgia Institute of Technology.

Evidence of carbonate-bearing rocks in multiple sites across Mars, including Lucaya crater have been highlighted by the study. In Lucaya crater, 3.8 billion years old carbonates and clays were buried by as much as 5 km of lava and caprock.

The carbonates on the planet were identified by the researchers using data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), which is on the Mars Reconnaissance Orbiter. CRISM through vibrational transitions of the molecules in their crystal structure that produce infrared emission collects the spectral fingerprints of carbonates and other minerals.

In order to gain insights into the geologic features associated with carbonate-bearing rocks, the team combined CRISM data with images from the High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) on the orbiter, as well as the Mars Orbiter Laser Altimeter (MOLA) on the Mars Global Surveyor.

The extent of the global distribution of martian carbonates is not yet fully resolved and the early climate on the red planet is still subject of debate. However, this study is a forward step in understanding the potential habitability of ancient Mars.

(With inputs from PTI)