Rover finds offer a glimpse into the ancient landscape of the Red Planet

CU Boulder geologist Lisa Mayhew is among the scientists working to recreate the story of an ancient landscape that wouldn’t look out of place in Utah — only that terrain is on Mars, millions of miles from Earth.

Mayhew is a member of the science team for NASA’s Mars 2020 mission, led by the Jet Propulsion Laboratory in Southern California. In August, she and her colleagues published some of the first results from the Perseverance rover’s exploration of the Red Planet.

The results take a deep look at the Jezero crater. More than 3 billion years ago, a large asteroid struck Mars, forming this geological feature that stretches almost 30 miles and contains rolling sand dunes and rugged cliffs. With a suite of scientific instruments aboard the Perseverance rover, which is about the size of an SUV, researchers have begun to probe the landscape’s past – showing how igneous rock shaped the crater floor and how water reshaped the rocks over time , in which it was formidable lake probably filled this region.

“We have a lot of information from orbit that informs us what we think about the geology, mineralology and chemistry of Mars,” said Mayhew, a research associate in CU Boulder’s Department of Geological Sciences. “But getting a rover there is an incredibly valuable tool to make sure we really understand what’s happening.”

The new results are a coup for this intrepid machine. The more than 1 ton Perseverance landed on Mars on February 18, 2021. Since then, she and Mayhew have been busy. In more than 570 Martian days, or “sols,” the rover has explored almost 8 miles of the planet’s surface. The new studies focus on Perseverance’s first year, during which the rover surveyed geological formations and features along the crater floor, including two named Máaz and Séítah.

Mayhew, who had previously only studied rocks on Earth, sees the mission as a chance to expand her skills as a geologist and, at least indirectly, set her feet on another world.

“I realize sometimes how crazy it is that I’m doing what I’m doing,” she said. “I am truly grateful that I had the opportunity to be a part of this groundbreaking science.”

Written in rock

Jezero Crater may look dry and dusty today, but it would have been almost unrecognizable more than 3 billion years ago. Here, water pouring out of a bay fed a lake that grew and shrank over the eons.

Mayhew and her colleagues attempt to flesh out the timeline of this wetter past.

The team’s initial results are targeting two geological formations, specifically: Máaz, Navajo for “Mars,” a feature that appears to overlie the larger Séítah, Navajo for “in the sand.” To study this terrain, the researchers relied on several instruments on board the Perseverance, including SuperCam. This pivoting instrument sits on top of the rover and uses laser light to quantify elements and identify minerals present in different rocks.

Mayhew is the co-author of two articles, led by Ken Farley of the California Institute of Technology and Roger Wiens of Los Alamos National Laboratory, that describe Perseverance’s first year on Mars. The studies were published in the journals on August 25 Science and scientific advances. Other research teams simultaneously published additional findings from the mission.

The group’s findings point to a surprising origin of these formations: a body of hot, molten rock may have existed at the crater floor, which settled and cooled in several stages, possibly forming both Séítah and Máaz. Alternatively, Máaz may have formed when separate lava flows entered the crater.

“One idea is that this was a single body of rock formed by cooling magma underground,” Mayhew said. “But another model is that Máaz may have been separately formed by lava actively flowing on the surface of Mars.”

The project touches on a question that has motivated much of her decades-long career: how is life reflected in some of the most unlikely places on our planet?

In 2007 and 2008, Mayhew sailed on research cruises collecting rocks from the bottom of the Pacific and Atlantic to learn more about microbial life in hydrothermal systems. In 2015, she participated in an International Ocean Drilling Program research cruise that drilled underground in a hydrothermal system to access actively reacting rocks. At these sites, rocks react with water and produce chemicals like hydrogen gas — nutrients that support vibrant communities of microbes, which in turn can support more complex life like crustaceans and other invertebrates.

“My research has always been about how water changes rocks and how that process can support life,” Mayhew said.

return to earth

To find out if rocks at Jezero supported life billions of years ago, Mayhew and her colleagues need to look much more closely at these Martian boulders — under the microscope in laboratories on Earth.

During her mission, she explained, Perseverance uses a drill to excavate about 40 geological samples from Mars and store them in sealed vials. NASA is working with the European Space Agency (ESA) on separate missions that will travel to Mars to pick up 30 of these tubes and return them to Earth.

Mayhew is one of 15 scientists on the mission’s Return Sample Science Team. She and her colleagues work with other team members and the Perseverance staff to decide which stones the rover should collect. To date, the team has filled 13 of their sample tubes, 12 with rocks and one with an atmosphere sample, and plans to collect more rock samples soon. The team also sealed two “witness” tubes to collect dust and particles in the atmosphere, allowing researchers to measure contamination that might be present during the sampling process.

Mayhew said the transition from being a geologist on Earth to being a scientist working on an alien world has been difficult but rewarding.

“It felt like a big learning curve. I don’t have the background that a lot of people on the team have, particularly those who have worked on Rover missions since Opportunity and Spirit came along in the early 2000s,” Mayhew said. “I’m constantly trying to keep my ears open and learn from them.”

In March 2022, Perseverance left the crater floor for perhaps the mission’s most exciting terrain – the delta. Here the team will collect rocks that were deposited on the crater floor when water once flowed on Mars.

Perseverance and Mayhew show no sign of stopping: “It’s a hectic schedule and we need to keep moving.”