Red dust colors Mars with its distinctive color, from the surface to the sky. But NASA's Perseverance rover saw another patch of color in the rusty reddish tones. On almost every site the robot visits, there is a mysterious purple layer.
The color forms a thin, smooth layer on some stones, and leaves a clump like paint on others. In other rocks, this layer appears as if it was partially frozen in a magenta color.
"The color hits rocks of all shapes and sizes, even small pebbles don't escape the purple color. But how exactly did this layer form? I don't have a good answer," said Ann Ollila, a geochemist at Los Alamos National Laboratory who presented the initial analysis. layer at the American Geophysical Union (AGU) conference.
Scientists are eager to know more about this layer. There's a lot to look forward to as they continue to do their analysis. The origins of the mysterious spots could help reveal clues to Mars' past, including whether Mars once harbored ancient life.
As quoted from National Geographic, when layers form, they can encode information about surrounding conditions in their chemical and mineral makeup, helping scientists reconstruct long-lost environments. They can also store more direct evidence of life. Scientists are eager to know more about this layer.
There's a lot to look forward to as they continue to do their analysis. The origins of the mysterious spots could help reveal clues to Mars' past, including whether Mars once harbored ancient life.
On Earth, microbes help create many similar layers of rock. Studying this type of crust could also help scientists better understand how other worlds operate.
"How universal are geological processes, and how do they change the planet?" asked Cassandra Marnocha, an environmental microbiologist at Niagara University, New York, United States.
Purple "Painting" Everywhere
The purple layer of Mars was found in the Jezero crater, in a pockmarked area 45 kilometers wide that was blown up by a meteorite impact billions of years ago that once housed an ancient lake.
Perseverance landed in the crater in February 2021 and since then, it has been roaming over it. At almost every stop along the rover's route, flashes of purple appear in the images it captures.
Ollila and his colleagues took a closer look at this layer using the SuperCam rover, which can shoot a laser at the rock to vaporize a small amount of material and refine its elemental composition.
Each laser shot also carved a small hole in the surface and emitted a flick-like sound. A microphone on the rover picks up the noise, allowing scientists to hear as the laser cuts through the coating and into the rock below. These sounds also reveal clues about some of the rock's properties, such as its hardness.
Preliminary results from this analysis suggest that this purple color appears to be a softer and chemically distinct layer from the underlying rock.
"The Mastcam-Z images suggest the layers may contain a type of iron oxide, and SuperCam analysis shows that they are enriched with hydrogen and sometimes magnesium," Ollila said.
The presence of hydrogen indicates that water played a role in the formation of the purple spots. Iron oxide also refers to the presence of water. Further study could unlock a wealth of information about the Red Planet's past when it was still wet, including how long water remained in Jezero crater and, possibly, the chemical nature of the lake itself.
"The presence of the purple layer could be an important part of the story," said Bradley Garczynski of Purdue University who also presented analysis of the purple layer on Mars at the AGU conference.
However, the location of the purple patch presents a bit of a mystery. The current Perseverance route does not intersect lake sediments, but rather rocks formed from cooling magma. How the rocks arrived at their current location at the bottom of the crater, and when and how the water came into contact, remains uncertain.
So far, the team has only analyzed a few samples, and they still face many challenges. SuperCam's different chemical readings and laser sound changes don't always seem to go hand in hand.
Separating the chemical signatures of the layers, underlying rocks, and dust that has always existed on the Martian surface is extremely complicated. And the strong Martian winds are a problem when scientists can hear the sound of lasers.
On Earth, such layers are often associated with the presence of life, which means they could be of great benefit to astrobiologists.
Rock nooks and crannies can create small shelters for microbes in harsh environments, or moisture in dry landscapes.
Some of these microbes help make coatings by metabolizing metals that are rubbed off the stone surface or dissolved in water. On Mars, coatings might even help preserve evidence of ancient microbes long after their deaths by preventing Mars' intense solar radiation from damaging fine organic structures.
The newly discovered coatings at Jezero lack the manganese needed to be considered a varnish, but that doesn't mean they can't be linked to ancient microbial life.
The team hopes to further decipher the chemical layers of the color and look for organic material associated with the Martian crust, which could hint at the presence of microbes.
Perseverance itself has drilled samples of Martian rock as they traverse the craters, sealing them in tubes that will be stored on the Martian surface for future missions to return to Earth.
Given that the purple layers are fragile, Ollila hopes some of them can withstand the sampling process so scientists can examine them more closely in the future.