Data from a small planet

Data from a small planet

(NASA / JPL-Caltech) On November 16, 2021, NASA Mars rover Curiosity photographed panoramic images of this scene on Mars twice, at approximately eight-hour intervals. Engineers combined the two scenes to produce this re-creation.

Copyright © 2022 Albuquerque Journal

Mars, the wet planet?

OK, scientists probably will not hang that handle on the fourth stone from the sun and the second smallest planet in the solar system now. But if they had been around 3.5 billion years ago, they might have considered it.

Information gathered by NASA’s Mars rover Curiosity shows that the planet was once a much wetter place than it is now. Analyzes of the Glen Torridon region in the Gale Crater, created by a meteor shower on Mars 3.7 billion years ago, indicate that the bedrock there was altered by groundwater.

“There is a block of evidence that when the crater was formed, Earth and Mars were equal in water and atmosphere,” said Patrick Gasda of the Los Alamos National Laboratory’s Space and Remote Sensing Group. “Mars underwent a climate change. All signs point to a hot, wet Mars in the past. Now Mars is cold and dry. What caused Mars to divert from Earth? If we could find out, we might be able to prevent this. . ”

Crater lakes, hot rocks

Curiosity’s mission was to discover if Mars ever had the right environmental conditions to support small life forms called microbes. The rover takes rock, soil and air samples for analysis on board. It looks for rocks formed in water and / or shows signs of organic matter.

Patrick Gasda, Los Alamos National Laboratory researcher, in a lab with the test unit for the ChemCam instrument used by Mars rover Curiosity to explore the role of water on Mars and the possibility that the planet could have supported life. )

Gasda, 37, is the lead author of a study recently published in a special issue of the Journal of Geophysical Research Planets, which describes what Curiosity found in the most chemically diverse part of the Gale Crater, which is 96 miles wide and contains a 3-mile-high mountain. of layered sediments called Mount Sharp.

“The Gale crater had a lake about 3.5 billion years ago,” Gasda said. “There could have been a deep lake there, or maybe just a few small or shallow lakes with small rivers in between. It would have been a friendly place for life – like bacterial life. But we have not found any evidence of life yet. “

He said the crater’s Glen Torridon region probably represents the last stages of a wet Mars.

“And we want to understand the sea sediments to give us a baseline for what happened just before Mars’ climate changed,” Gasda said.

Scientists believe that the lake in the Gale crater was formed by groundwater seeping in and rivers, fed by rain and melting snow, flowing in. Gravel, sand and silt came in with the river water.

For millions of years, these sediments continued to build up in the crater. Even after Mars began to dry up and rivers stopped flowing, the wind blew sand and dust into the crater, possibly filling it to the brim. But then the winds start to claw away at the sediment bowl, until what remains today is Mount Sharp.

“Erosion of wind could have taken about a billion years,” Gasda said. “The base (on Mount Sharp) occupies between one third and two thirds of the crater. It is large. It has been compared to (Tanzania’s) Mount Kilimanjaro.”

Each layer of sediment locked into the rock records a chapter that reveals the environment that created it. Curiosity reads these chapters and reports back to Earth using its ChemCam instrument, developed at Los Alamos and a French space laboratory.

ChemCam records chemistry and images from Curiosity’s four cameras to look for physical and chemical changes in rocks.

“We see rounded tubers that have a different color – darker tone – than the surrounding material,” said Gasda. “The water in a crater will react with rocks if it is there for a long time. It is the darker material that gets concentrations of water. That is how we know that this substance has formed in water.”

Curiosity also discovered large veins with strange chemistry, including dark veins with high iron and manganese and fluorine-rich lighter veins.

“We did not expect to find veins with chemistry like this in Glen Torridon,” said Gasda. “Our hypothesis for how these things formed was that the first (meteor) impact heated rocks near the crater, groundwater flowed through these rocks and this warm water probably extracted elements such as fluoride from these rocks.”

Heated water, or hydrothermal, systems would bring elements such as iron, nickel, sulfur and manganese to the surface of Mars, and microbes use these elements as an energy source.

NASA’s Curiosity Mars rover uses its mast camera in March 2020 to capture a scene on the planet’s surface. In the background is the top of Mount Sharp, a 30 km high mountain that rover has climbed since 2014. (NASA / JPL-Caltech / MSSS)

“We now believe that things like this happened all over Mars,” Gasda said. “Every time a major impact occurs, you would have hot water circulating. It is possible that all craters on Mars had similar circumstances. Mars could have been friendly to life across the planet.”

What is life?

Gasda holds a bachelor’s degree in chemistry from Ursinus College in Pennsylvania and a doctorate in geology from the University of Hawaii.

“I’ve been interested in everything to do with space and rocks since I was little, but I went to college to do chemistry,” he said. “I worked in the industry for a while but did not like it. Eventually, I came back to what I really wanted to do, which was geology and planetary science, in graduate school. ”

A child-like enthusiasm is still evident when he talks about exploring Mars. He thinks it’s crazy exciting that we land rovers on a planet that is further away from the earth than the earth is from the sun.

Curiosity was launched in November 2011 and landed on Mars in August 2012.

“Curiosity had its own camera and took pictures on the way down,” said Gasda. “It was looking for places that were flat so that it would have a good place to land.”

Originally, Curiosity’s assignment was set at two years. But two years came and went almost eight years ago and the rover continues to drive a truck.

Rovern’s goal was to discover the role of water on Mars and whether the planet could have provided life or not. So far, so good.

“Water was there and it would have been nice if there was life,” Gasda said. “We simply do not have a way to measure it.”

He said that perhaps the rover Perseverance, which landed on Mars in February 2021, could find a fossil that would prove that life once existed on the planet.

He’s not talking about something like Brontosaurus’ bones.

“The most realistic would be fossils of bacteria, tiny tiny spots,” he said. “You can look for concentrations of carbon, hydrogen, nitrogen, required for life as we know it.”

But what if there is life that we do not know.

“As far as we know, only the earth has life on it,” Gasda said. “But we do not know enough about life to be safe. We only have one example of a biosphere. If we could find another example of life, we could understand life more broadly.

“If we’re the only ones here, we should do a better job of protecting this life.”

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