Settling the \'Life on Mars\' debate once and for all ?

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https://www.earth.com/news/mars-curiosity-rover-finds-sulfur-crystals-martian-rock-hints-at-possible-life/


Curiosity rover cracked open a rock and may have settled the 'life on Mars' debate

March 22, 2025

Imagine taking a leisurely Sunday drive, and you accidentally smash something on the road that turns out to be an unprecedented scientific revelation. Well, that’s exactly what happened to NASA’s Curiosity Mars rover on May 30, 2024 when it struck sulfur.

While working its usual Martian shift, the rover stumbled upon, rather drove over, a rock and cracked it wide open, revealing a sight never before seen on Mars – a dazzling display of yellow sulfur crystals.

This unexpected discovery was relayed to a team of astounded scientists, including Ashwin Vasavada, the Curiosity’s project scientist from NASA’s Jet Propulsion Laboratory in Southern California.

“Finding a field of stones made of pure sulfur is like finding an oasis in the desert. It shouldn’t be there, so now we have to explain it. Discovering strange and unexpected things is what makes planetary exploration so exciting,” Vasavada enthused.

Sweet sulfur surprise on Mars

The bright, odorless crystals found by Curiosity open a window into a new chapter of study.

Researchers want to know what factors created this elemental form and how it can exist alongside other deposits that speak to the planet’s watery past.

Since October 2023, Curiosity has been rambling about in a sulfate-rich region of Mars. Now, sulfates aren’t exactly Martian novelties.

These salts, formed as water evaporates, had been detected before, but only as constituents of sulfur-based minerals – mixtures of sulfur and other stuff. But this time, it was pure, elemental sulfur, a first of its kind.

What’s so peculiar about this elemental sulfur? Well, contrary to the stinkiness associated with hydrogen sulfide gas, elemental sulfur is odorless.

Its formation requires specific conditions not previously linked to this Martian location. Hence, the revelation of an entire field of bright, sulfur-laden rocks is indeed something to marvel at.

Sulfur as a signal for life on Mars

Sulfur is an important element for understanding the potential for life, both on Earth and beyond. Certain microorganisms on our planet depend on sulfur compounds as an energy source.

The presence of sulfur on Mars, even in forms discovered in earlier missions, has always raised questions about ancient habitats.

Water influences the formation of sulfates, and water stands out as a critical ingredient for biology.

Finding pure sulfur, though, points to specialized conditions that could expand possible scenarios for past microbial life on the Red Planet.

Sulfur compounds also reveal information about Mars’s potential hydrothermal systems, volcanic activities, or ancient lakes and seas – habitats that might have supported life.

They are involved in chemical reactions that produce energy, a survival mechanism for some Earth microbes in extreme environments like deep-sea hydrothermal vents.

The identification of sulfur on Mars raises questions about the planet’s historical habitability. It suggests a range of chemical environments that could have supported microbial life.

While sulfur alone doesn’t confirm the existence of life, its presence alongside other life-sustaining elements like carbon, hydrogen, nitrogen, oxygen, and phosphorus strengthens the case for past life on Mars.

Scaling Mount Sharp

Curiosity has climbed Mount Sharp for more than seven years, examining its layered formations.

Each layer represents a separate phase of the planet’s development, offering glimpses of ancient river networks, lake sediments, and shifting climates.

Data show that different types of minerals, including sulfates, appear in these layers, hinting at cycles of evaporation and chemical alteration that occurred when water was likely more plentiful.

Mars’ Gediz Vallis and sulfur crystals

A site drawing particular interest is the Gediz Vallis channel. Researchers suspect it was shaped by water-driven events and landslides that left a jumble of rocks at the bottom.

Findings suggest that both factors had a hand in the formation of these Martian landscapes (see the mage at the bottom of the page).

Becky Williams, a scientist with the Planetary Science Institute in Tucson, Arizona, and deputy principal investigator of Curiosity’s Mast Camera, has studied these processes.

“This was not a quiet period on Mars. There was an exciting amount of activity here. We’re looking at multiple flows down the channel, including energetic floods and boulder-rich flows,” she explained.

Drilling for more sulfur clues on Mars

Curiosity’s drill has stayed busy near the newly found sulfur field. On June 18, the rover created its 41st borehole in a rock called “Mammoth Lakes.”

That powdered sample is now under scrutiny. Researchers hope to see if the elemental sulfur sits alongside compounds that might reveal the chemical history of Mars.

Identifying the mixture of ingredients in the soil can shed light on previous hydrothermal processes, environmental conditions, or even the faint possibility of microbial life.

The article continues...

Panorama of Gediz Vallis region of Mars taken by Curiosity rover. Credit: NASA
Post Merged: March 24, 2025, 11:13:35 AMDid Mars harbour life? One of the strongest signs yet is spotted in a peculiar rock

https://www.nature.com/articles/d41586-025-00772-2?utm_source=Live+Audience&utm_campaign=0f2db24a66-nature-briefing-microbiology-20250320&utm_medium=email&utm_term=0_b27a691814-0f2db24a66-498702756

12 March 2025

The intriguing chemistry of a rock collected by the Perseverance rover could trace to microbial activity — or not.

NASA’s Perseverance rover has found possible hints of ancient life on Mars ― one of the strongest signs yet of Martian life, according to planetary scientists. Dark-rimmed ‘leopard spots’ in a rock studied by the rover last year could be the remains of Martian microbial activity, researchers said at a conference today.

Dark-rimmed ‘leopard spots’ in a rock studied by NASA’s Perseverance rover last year could be the remains of microbial activity on Mars. The rings aren’t a sure sign that microbes once thrived on the Red Planet; the only way to know for certain is to analyse a sample of the leopard-spotted rock here on Earth. Perseverance has a sample awaiting a ride off Mars for precisely that purpose. For now, the rings are being treated as ‘an intriguing signal’ of ancient Martian life, but far from a sure thing, said researchers at a conference yesterday.

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https://phys.org/news/2025-03-molecules-unprecedented-size-mars.html

March 24, 2025

Organic molecules of unprecedented size discovered on Mars

Scientists analyzing pulverized rock onboard NASA's Curiosity rover have found the largest organic compounds on the red planet to date. The finding, published Monday in the Proceedings of the National Academy of Sciences, suggests prebiotic chemistry may have advanced further on Mars than previously observed.

Curiosity's Sample Analysis at Mars (SAM) mini-lab and found the molecules decane, undecane, and dodecane. These compounds, which are made up of 10, 11, and 12 carbons, respectively, are thought to be the fragments of fatty acids that were preserved in the sample. Fatty acids are among the organic molecules that on Earth are chemical building blocks of life.

Living things produce fatty acids to help form cell membranes and perform various other functions. But fatty acids also can be made without life, through chemical reactions triggered by various geological processes, including the interaction of water with minerals in hydrothermal vents.

While there's no way to confirm the source of the molecules identified, finding them at all is exciting for Curiosity's science team for a couple of reasons.

Curiosity scientists had previously discovered small, simple organic molecules on Mars, but finding these larger compounds provides the first evidence that organic chemistry advanced toward the kind of complexity required for an origin of life on Mars.

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The new study also increases the chances that large organic molecules that can be made only in the presence of life, known as "biosignatures," could be preserved on Mars, allaying concerns that these compounds get destroyed after tens of millions of years of exposure to intense radiation and oxidation.

This finding bodes well for plans to bring samples from Mars to Earth to analyze them with the most sophisticated instruments available here, the scientists say.

"Our study proves that, even today, by analyzing Mars samples we could detect chemical signatures of past life, if it ever existed on Mars," said Caroline Freissinet, the lead study author and research scientist at the French National Center for Scientific Research in the Laboratory for Atmospheres, Observations, and Space in Guyancourt, France.

In 2015, Freissinet co-led a team that, in a first, conclusively identified Martian organic molecules in the same sample that was used for the current study. Nicknamed "Cumberland," the sample has been analyzed many times with SAM using different techniques.

Curiosity drilled the Cumberland sample in May 2013 from an area in Mars' Gale Crater called "Yellowknife Bay." Scientists were so intrigued by Yellowknife Bay, which looked like an ancient lakebed, they sent the rover there before heading in the opposite direction to its primary destination of Mount Sharp, which rises from the floor of the crater.

The detour was worth it: Cumberland turns out to be jam-packed with tantalizing chemical clues to Gale Crater's 3.7-billion-year past. Scientists have previously found the sample to be rich in clay minerals, which form in water. It has abundant sulfur, which can help preserve organic molecules.

Cumberland also has lots of nitrates, which on Earth are essential to the health of plants and animals, and methane made with a type of carbon that on Earth is associated with biological processes.

The article continues...


The long-chain organic molecules decane, undecane, and dodecane. These are the largest organic molecules discovered on Mars to date. They were detected in a drilled rock sample called "Cumberland" that was analyzed by the Sample Analysis at Mars lab inside the belly of NASA's Curiosity rover. The rover, whose selfie is on the right side of the image, has been exploring Gale Crater since 2012. An image of the Cumberland drill hole is faintly visible in the background of the molecule chains. Credit: NASA/Dan Gallagher