NASA’s Perseverance rover, which landed on Mars nearly two years ago, has released treasure troves of data, key observations and long-awaited geological findings from its first moves across the Martian surface.
Four papers, published Thursday in the journal science AND Advances in science, report new details of the planet’s geologic history gleaned from Mars’ Jezero crater, the site of an ancient meteor impact where the rover touched down just north of the Martian equator. The planet was once home to vast amounts of lava flows and rocks that, with the presence of water, could have supported ancient life.
Kathryn Stack Morgan, deputy project scientist for the Mars 2020 Perseverance Rover mission, says that while one Martian region does not necessarily reflect the astrobiology of the entire planet, Perseverance’s findings provide evidence to connect what scientists have learned there to other regions. The new discoveries also challenge what people know about habitable environments, because it’s possible that any life that arose from Mars’ primordial soup would look completely different from anything we’re familiar with.
Here are five rock solid moments from Perseverance’s escapades exploring what was once an ancient Martian lake, as detailed in these documents.
The surface of Mars is sprinkled with various rocks.
Rocks are some of the best holders of climate and habitability, but scientists weren’t sure Mars had the range of rocks that exist on Earth. “Prior to the landing, there was a lot of speculation about whether the crater floor rocks were sedimentary,” says Stack Morgan, who co-authored the paper. “As much as we liked sedimentary rocks for their astrobiological potential, we really hoped to find diversity.”
And they found it sooner rather than later: One of Perseverance’s most exciting discoveries revealed that the floor of Jezero Crater is home to a significant amount of igneous rock, stones that can only form from the cooling and solidification of liquid molten magma . Basically, volcanic activity may have been a more important process on that part of Mars than scientists previously thought.
Was Mars a Slow Cooler?
A study found that the igneous rocks found on Perseverance are composed of coarse-grained olivine, a common rock-forming mineral that is also abundant on Earth. Olivine is one of the first minerals to crystallize from magma, but on our planet, these grains are smaller and glassier than the coarse Martian stuff. Researchers hypothesize that this finding could mean that Mars has cooled rather slowly, deep underground.
While the rover also found evidence of large amounts of olivine on the surface, its presence may signal that the mineral is equally widespread in other regions beyond Jezero Crater. In such a case, the researchers note that this olivine-enriched soil can be explained by lava flows on Mars that are thicker than on Earth.
Martian rocks have the right stuff for life.
Although NASA has yet to detect life on the Red Planet, researchers found evidence that the planet may have been more habitable during the late Noachian period, from about 4.1 billion to 3.5 billion years ago. Two of the four studies describe how magma-produced rocks on Mars have been altered by water. But why is water flowing through rocks a big deal?
On Earth, when water and certain igneous rocks interact with each other, the reaction can yield a variety of nutrients, including H2 or CH4, potential energy sources for life. This creates a diverse biome, a utopia ripe for microbial life. Because of the Persistence expedition, scientists discovered that rocks on the crater floor appear to contain salt minerals such as sulfates, perchlorates, and carbonates, signs that liquid water flowed through these rocks. These rocks also contain simple organic molecules, which could have helped preserve habitable environments.
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Although the igneous rocks they found were discovered in an active volcanic area—not an environment that humans would consider conducive to existence—the study notes that there is evidence that the rocks experienced water at some point in its history and may have once all ingredients to support ancient life. “It really opens up the possibilities out there in terms of the kinds of habitable environments that once existed on Mars,” says Stack Morgan.
Welcome to the underground layers.
While some researchers focused on the uppermost crust of the crater, one team decided to examine the ground beneath the rover, using an instrument called the Radar Imager for the Mars Underwater Experiment (RIMFAX). Their paper chronicles the first eight months of the mission, during which RIMFAX received a continuous radar image of the Martian subsurface. The radar revealed new properties of the bedrock about 50 meters below the surface of Jezero: The internal morphology of the crater can be categorized as either a magmatic layer, formed by igneous rocks undergoing chemical changes in mass, or a sedimentary layer, the impurities of commonly formed in aquatic environments on Earth. .
According to one of the studies, the presence of these buried structures is “consistent with a history of long-lived magmatic activity and a history of multiple water episodes,” effectively supporting the theory that water once flowed freely on Mars.
Mars samples will arrive in the early 2030s.
One of the most important aspects of the Persistence mission is its capacity to return the Mars sample. The rover was built to collect about 35 rock and soil samples to be transported back to Earth for detailed laboratory analysis. This will be a complex, multi-year mission: scientists likely won’t have the samples until the early 2030s. In addition to allowing us to look at the history of the Martian surface, one study notes that the returned samples could also provide insight into the role that Mars’ magnetic field played in its evolution.
On Earth, our geological history is driven by dates and events in the past. But because scientists’ time scale for Mars is largely relative and can only be estimated relative to the age of rocks from the Moon, geologists can have a hard time trying to use this method to date the surface. “We can look at the surface of Mars and say, well, we think this thing is older than that thing,” says Stack Morgan. “But we don’t actually know when these events happened.”
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But by analyzing the returned samples, scientists can begin to determine precise ages and dates and truly revolutionize the geological time scale of Mars, says Stack Morgan. But there is still a lot to do until then.
“It was an incredible first year of the mission,” she says. “This is just the beginning for this whole effort and [we] I hope everyone is really excited about it as we are.”