February 21, 2022
UChicago proposal to study why Mars dried out selected for Curiosity rover mission
NASA has selected University of Chicago associate professor of geophysical sciences, Edwin Kite, to join the Mars Curiosity rover mission as a participating scientist. Kite, along with fourth-year Ph.D. student Sasha Warren, hopes to expand the rover science team’s understanding of climate history on Mars.
In August of 2012, the largest and most capable rover ever sent to Mars began exploring Gale Crater equipped with 10 science instruments, including 17 cameras, a laser to vaporize rocks, a drill to collect samples, and an onboard sample-analysis suite. About the size of an SUV, Curiosity moves to targets, hunts for rocks, and measures the chemical fingerprints present in different rocks and soils to determine their composition and history, especially their past interactions with water. Curiosity has amassed a catalog of more than 832,000 raw images from which to understand the red planet.
“The rover can get up close and take ground-truth images that you can’t get from orbit,” said Kite, an expert in both the history of Mars and climates of other worlds. “Curiosity can get higher resolution images of the layers and the patterns of strata which you can’t see from orbit.”
“In fact, one element of the proposed work is to do ground truth, so compare the interpretations from orbit to the ground truth, and check if our interpretations from orbit are correct,” he said.
Kite and his students—some of whom will cycle onto the team when Warren graduates—aim to understand what the Martian climate was like billions of years ago, why Mars dried up, and the mechanism responsible for past habitability.
“As part of the science team, we will assist in the day-to-day rhythm of looking at data and deciding what to target next, sequencing the data collection, and recommending a drive direction,” Kite said.
By pairing the activity of the rover with satellite images, scientists have already made several key discoveries about Mars. For example, they learned that Gale Crater, which is dry today, was repeatedly flooded by liquid water. Additionally, they found that Mars’s ancient environment would have been habitable for Earth microbes.
Curiosity has detected organic matter entombed in the rocks as reduced carbon. “The story is ongoing as to whether that organic matter was produced by an ancient ecosystem or a non-biological process,” Kite said.
Previously, Kite and his colleagues cataloged ancient riverbeds and elevation models to conclude that significant river runoff persisted on Mars later into its history than previously thought. The hope now is to understand what kind of weather fed those rivers.
Kite and Warren will use their time gathering evidence of fractures, veins, and deformation features to distinguish between proposed explanations for water flow paths above and under the ground surface at the mound in the middle of Gale Crater that Curiosity is exploring.
“The rover science team can see a lot of evidence of liquid water, of complex mineral deposits associated with water, and ripples suggesting the direction of flowing water as well,” said Warren (they/their). Studying signatures of very salty water that has evaporated and layers of sulfate minerals may indicate if Gale Crater was hot and arid like Death Valley or gusty and snowy.
“One option is that Gale used to have a big, flat, dry lake called a playa in it, where water rises up underground from the subsurface,” they said. This would suggest that billions of years ago it was warm and watery for longer, and thus more favorable for life.
“The other option is wind blowing dust around and very occasionally snow that melts also forms these minerals,” they said, suggesting a very different case, where Mars was very cold and, for a shorter amount of time, wet.
But recreating climate history from images and elevations does not easily solve the puzzle.
“It’s a pretty complex area,” they said. “We are not sure even if the crater filled up and then eroded back to form the mountain, or if the mountain formed in a very dry environment.”
Now they can join the team directing Curiosity to seek requisite data to help tell the full climate story and necessary underpinning for understanding habitable conditions.