Tremendous Mars Lake: Does Evidence of Life Hide Beneath Planet’s Surface?

Is the key to discovering evidence of life on Mars just beneath the surface? A group of planetary geologists believe watery, underground channels beneath a 92km crater on the planet may hold the answer.

After studying the McLaughlin Crater, and identifying sedimentary rock layers at its base containing clay and carbonate minerals, researchers were able to use images and data captured by NASA's Mars Reconnaissance Orbiter to make their hypothesis, Wired reported. The two minerals are formed on Earth by interacting with water, but analysis of the crater's topography showed a flat surface and no large inflow channels. Meaning any water that was present in the crater billions of years ago came from beneath the planet's surface.

"Taken together, the observations in McLaughlin Crater provide the best evidence for carbonate forming within a lake environment instead of being washed into a crater from outside," said lead author on the Nature Geoscience paper and Natural History Museum planetary scientist Joseph Michalski.

Scientists continue to wage a battle to prove the existence of life on Mars, making some remarkable strides in just the last year. In 2012, NASA's Curiosity Rover provided evidence of an ancient river on the planet and evidence of water in its soil, and analysis of a Mars meteorite displayed water levels 10 times greater than any other Earth-bound Mars sample, according to Wired. On the flip side of that coin though, the Curiosity Rover found no traces of methane - produced by biological activity on Earth - in atmospheric samples on Mars.

This is all a big part of the reason scientists believe much of the future of their research depends on going below Mars' surface.

"If Mars's climate was never stable, that would have been a challenge for life," Andrews-Hanna told Nature last year. "But as you go deeper in the subsurface, things become more stable."

Michalski and his team of researchers began looking at the biggest, deepest craters on Mars actually trying to disprove the existence of these lakes, but when he got to McLaughlin, the evidence was so overwhelming he couldn't deny it.

At 2.2km deep, McLaughlin presented the best chance to find evidence of water on Mars' surface for Michalski. With the added help of data collected from NASA's Thermal Emission Spectrometer and Imaging System the minerals were identified. Ancient water channels were also discovered about 500m above the crater's base, indicating a former lake surface. The McLaughlin crater was a lake between 3.7 billion and four billion years ago, the team now estimates.

But while the find McLaughlin upended Michalski's theory, it didn't convince him entirely that Mars was once covered with such "upwelled" lakes.

"We suggest that upwelling might have occurred but it was limited to only the deepest basins, and when it occurred, it produced sediments from alkaline fluids reflective of long transport distances in a basaltic crust," says Michalski in his research paper.

Rather than opening up the beginning of many discoveries of ancient life on Mars, the scientist posits that further findings may actually lead to more revelations about the origins of life on Earth.

"We don't know how life on Earth formed but it is conceivable that it originated underground, protected from harsh surface conditions that existed on early Earth," he said in a statement.

"Due to plate tectonics, however, the early geological record of Earth is poorly preserved so we may never know what processes led to life's origin and early evolution. Exploring these rocks on Mars, where the ancient geologic record is better preserved than on Earth, would be like finding a stack of pages that have been ripped out of Earth's geological history book. Whether the Martian geologic record contains life or not, analysis of these types of rocks would certainly teach us a tremendous amount about early chemical processes in the solar system."