Aug. 12, 2022
UCalgary scientist studies Mars’ geology for signs the planet could have once supported life
The rocks on the surface of Mars could offer revealing clues about whether the Red Planet was ever habitable enough to support life.
To find out, the Canadian Space Agency, as part of the NASA-led Mars Science Laboratory mission, is funding a three-year study by Dr. Benjamin Tutolo, PhD, associate professor in the Department of Geoscience in the Faculty of Science.
Tutolo will study Mars’ approximately 3½-billion-year-old geological record by examining layers of sediment now being explored by the Curiosity robotic rover as it takes rock and soil samples on Mars’ surface.
“Our goal is to place constraints on whether Mars was habitable,” Tutolo says. “And if Mars was habitable, then we can think about whether it actually did evolve life.”
Tutolo and his research team will use data being collected by Curiosity as it slowly climbs up Mount Sharp. The mountain is in the centre of Gale Crater where Curiosity landed about 10 years ago.
As of May 1, 2022, Curiosity has travelled a distance of 27.8 kilometres on the Martian surface, according to NASA.
The rover is equipped with multiple analyzers that can determine the chemistry and mineralogy of Mars’ rocks or soil surface. Its Canadian-made instrument, the Alpha Particle X-ray Spectrometer, has analyzed 1,211 samples and sent 2,659 results back to Earth.
To help interpret what Curiosity is seeing on Mars, Tutolo and his team will do experiments in his laboratory, run numerical models on a computer, and conduct field research in British Columbia.
The team includes University of Calgary collaborators in the Department of Geoscience: professor Dr. Steve Larter, PhD, and associate professor Dr. Rachel Lauer, PhD.
Other participants include a UCalgary undergraduate (working on a project this summer), a master’s student who’ll start this September, and a postdoctoral researcher soon to be hired.
Team examining geological transition recorded in rocks
The focus of the team’s research is to study the geological transition from the oldest lake sediments in the deepest part of Gale Crater — where Curiosity began its exploration — to younger layers of sediment deposited in the crater and which formed Mount Sharp around 3½ billion years.
Tutolo says the geological evidence shows that the oldest rocks in the crater are from a “fluviolacustrine environment,” a river-fed lake which contained liquid water.
In contrast, the younger sediments on Mount Sharp contain magnesium sulphate salts — like the Epsom salt product used to relax muscles and relieve pain. Such salts are extremely soluble, so precipitating them involves evaporating off nearly all the water in a solution to produce the salts.
“We think that it must have been drier on Mars in order to precipitate those minerals. What we’re exploring is how that transition is recorded in the rocks,” Tutolo says.
In addition, the UCalgary team is conducting field research at the Basque Lakes near Cache Creek, B.C. These magnesium sulphate lakes — which are rare on Earth — are actively precipitating the same sulphate minerals found on Mount Sharp on Mars.
Although the Basque Lakes teemed with brine shrimp during a research trip in June, Tutolo says the question for similar sulphate deposits on Mars is: “Is there a point where it gets so salty that nothing could live there?”
The team has some unique tools to aid their research, including an anaerobic chamber in Tutolo’s lab used to investigate chemical processes that happen completely in the absence of oxygen.
Mars is red because of all the iron present in its surface. Also, the planet’s atmosphere doesn’t have anywhere near the 20 per cent of oxygen present in Earth’s atmosphere.
So the anaerobic chamber enables the team to simulate conditions on Mars, by conducting experiments in anoxic (no oxygen) environments on iron-driven chemical reactions in the presence of water, Tutolo explains.
Understanding Mars’ geological history can shed light on Earth’s evolution
Interpreting the geological transition on Mars will help answer the question of whether the planet’s environment would have still been habitable in a climate that became much drier and colder.
If there’s a potential that life did evolve, would it be able to exist on Mars’ surface at that time and, if so, what would that evidence look like in the rocks?
The slight variations in Earth’s movement — wobbling on its axis and expanding or contracting the distance of its orbit around the sun — has produced alternating ice ages and “hot houses,” or greenhouse climates, Tutolo notes. Mars’ movement through space changes a bit more dramatically than Earth’s, so those cycles are enhanced on the Red Planet.
“There was probably a period of time when Mars was getting warm and having water again, and going back and forth [from warmer to colder],” he says.
Knowing more about the geological history of early Mars can shed light on the history of early Earth, where the geological record from that time isn’t accessible, Tutolo says.
That’s because Earth’s crust is affected by plate tectonics whereby, over the eons, the surface gets subsumed into the planet’s mantle as continent-sized slabs of rock collide. So, precious little of early Earth’s surface still exists.
“But on Mars, all of those rocks have been there since they were deposited, some 3½ billion years or more ago,” Tutolo says. “So we can see those rocks on Mars and understand how life evolved on our planet, going from totally abiotic, or without life at all, to what it is today.”