Mars Water Indicates Habitability?

Arthur C. Clarke, writer of 2001: A Space Odyssey, predicted in 1971, “Whether or not there is life on Mars now, there will be by the end of this century.”

However, 2001 has come and gone and humans have yet to traverse the Martian landscape. There have been, however, substantial leaps in science to help bring us closer to detecting if the Red Plant has, in fact, held life and if it can someday be our home.

Brian Hynek, Associate Professor at the Department of Geological Sciences and Research Associate for Laboratory Atmospheric and Space Physics at the University of Colorado, is part of that ambitious, nomadic yearning. He’s been at it for two decades, first as an undergraduate student mapping potential landing sites on Mars for future missions; now he’s working on some of the last known deposits of salt lakes on the planet.

His most recent research mapped the digital terrain and makes a mineralogical analysis of the surface of Mars and indicated the dried up lakebed to be 3.6 billion years old.

“It looks like in the past there was a much thicker atmosphere that could support stable surface water and we’ve spent a lot of time over the years mapping out the ancient dried-up river valley systems in Mars,” explains Hynek, the lead author on the research.

The study examined a 18-square mile chloride salt deposit in Meridiani Planum, the location of NASA’s Opportunity rover. The carved terrain that once held chloride salt water has been discovered all over Mars due to multispectral orbital data or remote sensing data, according to Hynek. Using blue, green, and red wavelengths, the device can detect subtle curvatures and imbeds on the mineral surface.

However, discovering the lake itself was not as difficult as figuring out its age. Due to its small size, it was difficult for researchers to use traditional methods in placing a number to the terrain.

“It’s tough to try and reconstruct from remote sensing data what we know, but we do what we can,” admits Hynek. “For Mars we don’t actually have a rock in hand to radiometrically age them like what we do with rocks on earth. What we use instead is the density of impact craters on a surface.”

The location of the Opportunity Rover relative to the ancient lake and salt deposits. Since it’s about 100 miles away, there’s no chance this rover could drive to the past lake. However, the lake site is being considered as a landing site for a future mission. Photo courtesy of LASP/Bryan Hynek.

In essence, finding numerous deep craters would indicate a very old surface since it would have been hit by many comets and asteroids over the years. Since the deposit was so small, this traditional method was difficult.

Luckily, they found evidence of fluviolacustrine processes, implying an active hydrologic cycle. In other words, there seems to be remnants of an outflow into a big lava plane that has craters.

“We ultimately were able to get a pretty good crater age for when the lava was in place and the age of the lake was therefore younger,” explains Hynek. “Thankfully, it cut across a unit that was large enough to actually discern what the crater age was that the channel was from.”

Interestingly, 3.6 billion years ago is well past the time period when Mars is thought to have been warm enough to sustain large amounts of surface water planet-wide. Researchers were also able to estimate that the lake was about eight percent as salty as Earth’s oceans, which means it was quite hospitable for microbial life.

However, habitability was not the focus of research.

“Clearly this is evidence of water and a long-standing body of water, and anywhere on Earth where there is water, there is also life,” says Hynek. “It’s a logical jump to assume life, but we are still in the nascent stages to try and really uncover if Mars really had life.”

Hynek hopes to ultimately send a rover to Mars due to his research.

“We need ground troops now. Just like the other Mars rovers, [they] can tell us so much more of the local chemistry and habitability of the landing sites,” explains Hynek. “These salt deposits are candidates for upcoming missions where maybe the next rover would go by either NASA or European space agency.”

However, according to Hynek, it’s a long, convoluted process of multiple committee decisions and scientists offering input on where to send a land-rover on Mars. The ancient water basin is certainly under consideration since the goal is to look at potentially habitable environments and search for signs of past microbial life.

After all, we come from hunter-gatherers wandering on Earth. So, it’s no surprise the next place to wander to is Mars.

Feature photo, taken from the research paper, shows the salt deposits in green and the river valleys leading into the basin in blue. The overlaid colors and black lines are elevation data and the lake is estimated to have been 450 feet deep.