Study adds to the evidence that Mars transformed from wet to a dry planet
NASA’s Perseverance rover has found surprising volcanic rocks in Mars’ Jezero Crater, which was once a lake, according to a study published in Science and Science Advances.
The discovery was a complete surprise as the researchers initially expected to find sedimentary rocks formed by mud and detritus laid down by the ancient lake.
Water plays a vital role in the formation of most sedimentary rocks, according to experts.
“Before landing, there was quite a debate whether the crater floor was igneous or sedimentary,” Roger Wiens from the Los Alamos National Laboratory told Down To Earth. He studied the red planet’s under-surface features.
Researchers from NASA and multiple institutions in the United States and Europe contributed to the study published August 25, 2022.
Igneous rocks act as time capsules, recording the geological history of the planet, the researchers stated.
However, they also found signs of the igneous rocks formed by the solidification of magma being transformed by water.
“These water-altered rocks indicate the presence of water. As we know, water is an essential ingredient for a habitable environment,” Wiens added.
The team zeroed in on four different rocks within the Jezero Crater for sample collection.
“The Perseverance rover collected rock samples, representing diverse rock types present on the crater floor,” Amy Williams, assistant professor of geology at the University of Florida, told DTE.
She is one of the study’s authors that found evidence for water’s impacts on the alteration of igneous rocks.
Perseverance’s apparatus drilled a few centimetres into the rocks and extracted core samples.
“Each core is about the size of a piece of blackboard chalk. They are collected with some of the most complex and sophisticated hardware ever created,” David L Shuster, Professor at the University of California, Berkeley, told DTE.
He collaborated with Williams for the study.
The rover relayed pictures of the samples to the research team. It is also equipped with tools to analyse the chemical composition of rocks.
The rocks in the Séítah formation — a rock unit on the crater floor — possessed carbonates, indicating that they were formed after the rock reacted with carbon dioxide-rich water.
The Máaz formation, another Martian rock, thought to have been formed by the deposition of water or wind, also showed signs of being altered by water.
The presence of salt deposits, including sulphates and perchlorates, hint at the interaction between rocks and water, Williams added.
Some rocks sported an exfoliation texture — a form of mechanical breakdown. Water could be involved in this process, she added.
Another related study on the Séítah formation, found that it contained the mineral olivine in abundance. The olive-coloured mineral is also present on Earth. The researchers speculate olivine to have formed from slowly cooling magma below the surface.
“They are 1-2 millimetres thick, indicating that they were formed in a large underground magma chamber, yet they are currently at the surface,” Wiens explained, adding that this was a major surprise.
The new findings highlight some of the similarities shared by Mars and Earth, researchers said.
“In many ways, the landforms, the rock types of mars are very similar to those on Earth,” Shuster explained. However, the environmental conditions on Mars now are incredibly different from Earth, he added.
The evidence indicates that Mars has transitioned from a wet planet into the dry and cold desert it is today.
“Our study of Mars is teaching us much about our planet and how fragile and potentially fleeting are the environmental conditions that we now enjoy on Earth,” he highlighted.
The researchers have so far collected eight core samples. The entire mission will gather about 35 core samples from within and outside the Jezero crater, Williams noted.
The team hopes to study these samples extensively when they reach Earth in 2033 through the Mars Sample Return Mission. They aim to estimate when the igneous rocks were formed on the planet.
Additionally, researchers will look for potential signatures left behind by living organisms.
“On Earth, microorganisms can live within igneous rocks and harness metabolic energy and water from those fluids that altered the rocks,” Williams said.
If there were microorganisms in the Jezero crater floor, they might have been able to leverage those same conditions, she added.
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