Life on Mars?

Do you believe there was past life on Mars? Here’s what new NASA evidence indicates.

Dry, cold and barren. Mars doesn’t seem like a haven for life—at least not the kind humans are familiar with.

Scientists have wondered for decades if microbial life could have inhabited Mars in the distant past. One study, based on data collected by NASA’s Curiosity rover, is peeling back a layer of the mystery. Researchers measured the isotopic composition of carbon-rich minerals found in Gale Crater. This region is laced with dried rivers and gullies and was explored by the rover.

The findings Curiosity sent to Earth were not optimistic about the potential for life above ground. But that doesn’t rule out the possibility of an underground biosphere or even a surface biosphere that began and ended before the carbonates were formed.

This suggests two possible ways carbon-rich minerals could have form at Gale crater: a series of alternating wet and dry periods or salty-ice conditions. These two climate scenarios could be called ‘bleak’ and ‘bleaker’ when it comes to supporting life.

In an environment that swings from wet to dry, the region would shift from more habitable to less habitable. In the frigid temperatures near Mars’ equator, that environment would be hostile for life because most water would be frozen and inaccessible for chemistry or biology. Plus, what water was there was extremely salty, not pleasant for life.

This isn’t the first time scientists have theorized these climate scenarios for ancient Mars. Previous computer models have indicated these conditions before, but now they have isotopic evidence from Martian rocks.

Scientists have sought life on Mars since the first spacecraft touched down there in 1976. Mounting evidence from robotic explorers has shown the Red Planet to have been warmer and wetter, perhaps more than 3 billion years ago.

The Perseverance rover discovered a spotted rock with compelling signs of ancient dead Martian life, but a sample would need to be shipped to Earth for confirmation. A research team also reported evidence of a vast ocean of water below the planet’s surface. On Earth, where there’s water, there’s often life.

Scientists are interested in Mars’ carbon-rich rocks because they can hold clues about the environment in which they formed, such as the temperature and acidity of the water, and ingredients in the water and air.

The sampled rocks indicate lots of evaporation, suggesting a climate that could only support transient liquid water—that is, ice that melts when temperatures rise and the surface pressure is right.

The heavy isotope values in the rocks are much higher than what’s seen on Earth. They are the heaviest carbon and oxygen isotope values recorded for any Martian materials. Although evaporation can cause oxygen isotope changes on Earth, the changes in the Martian samples were two to three times greater.

But this doesn’t negate the possibility of life. Mars has a network of deep caves formed by ancient volcanic vents. Within the caves could be liquid water, traces of long-deceased bacteria or fungi, or perhaps even existing microbial life.

Caves can host complex ecosystems, including extremophiles that munch on rocks and convert the material into energy for life. So, many astrobiologists want to go spelunking on Mars. Would you like to join them?

 

https://www.msn.com/en-us/news/technology/past-life-on-mars-here-s-what-new-nasa-evidence-points-to/ar-AA1rWIgJ?ocid=hpmsn&cvid=5432d20e554e4f3ea664d26edcf277ee&ei=74