Mars’ Volcanic Past Hints Red Planet Was Icy Cold Billions Of Years Ago

For years, scientists have been debating the early history of Mars. Though we have already found valley networks, deltas, and lake deposits that suggest sometime in the distant past, about four billion years ago, the Red Planet had water, nobody really knows about the conditions that prevailed back then. Was the planet warm and wet or cold and icy?

This has been a major mystery for scientists who have been running models to determine the climate that prevailed on our neighboring planet. The exact answer to the question still remains unknown, but a new study from a group of researchers at the Purdue University, Indiana, provides a critical insight into it.

“There are people trying to model Mars' ancient climate using the same kind of models we use here on Earth, and they're having a really hard time doing it,” Briony Horgan, one of the authors of the latest work, said in a statement. “It's difficult to create a warm ancient Mars because the sun was a lot fainter then. The whole solar system was cooler”.

This is why instead of going with the conventional model approach, the group looked at the problem from a different perspective and delved into the history of Martian volcanism.

Some of the most studied regions of the planet have provided scientists enough evidence to conclude that volcanic activity was abundant on Mars. There are large and broad volcanoes as well as more than 100 lesser-known flat-topped mounds – called Sisyphi Montes – which might also be of volcanic origin.

On Earth, when lava erupts under a glacier or ice sheet and manages to breach through, the interaction between its heat and the meltwater leads to the formation of a distinctive, flat-topped volcano with steep sides. The formations are very worldwide and were only confined to the regions that had glaciers and active volcanism at the same time.

If they don’t breach through the surface of the ice, the volcanoes remain normal, cone-shaped. But, what’s important is the fact that in the first scenario the interaction between the lava and meltwater leads a distinct mineralogy.

That said, to look for something similar in the flat-topped mounds on Mars, the team at Purdue took a close look at the images taken by NASA's Mars Reconnaissance Orbiter‘s Compact Reconnaissance Imaging Spectrometers for Mars, aka CRISM instrument.

CRISM detects light in visible and infrared wavelengths and acts as a mineral mapper for the agency. In visible light, the instrument can pick features of iron, while in infrared, it can detect the presence of carbonate, sulfate, hydroxyl, and water incorporated in mineral crystals.

"Each rock has a specific fingerprint, and you can identify that with reflections of light," Sheridan Ackiss, the lead author of the study, said in the statement.

After scouring through the data, they identified three distinct combinations of minerals in the region, all of which have been associated with volcanoes present in glacial environments. The mineral combinations included gypsum, polyhydrated sulfates and a mixture of smectite-zeolite-iron.

"We now have two sets of data, minerals, and morphology, that say there had to have been ice on Mars at some point in time," Ackiss added. "And it was probably relatively late in Mars' history."

While further research into ancient Martian volcanism could bolster this case, it is worth noting that the presence of icy cold climate doesn’t affect the possibility of ancient microbial life on the red planet.

“Even if Mars was a cold and icy wasteland, these volcanic eruptions interacting with ice sheets could have created a little happy place for microbes to exist," Horgan concluded. "This is the kind of place you'd want to go to understand how life would've survived on Mars during that time."

The study titled "Mineralogic evidence for subglacial volcanism in the Sisyphi Montes region of Mars" was published in the journal Icarus.