NASA's Curiosity rover has been scouring Mars for signs of life for 11 years, and scientists recently said the car-sized robot discovered an unusual "polygonal mud block puzzle" in 2021, proving that Mars had Earth-like conditions 3.6 billion years ago that allowed microbes to survive.
The Curiosity rover discovered mysterious mud cracks in the bed of an ancient lake in Mount Sharp.
The Curiosity rover has reportedly discovered mysterious soil cracks in the bed of an ancient lake, suggesting that Mars once had a seasonal dry-wet cycle similar to Earth's.
This cycle is essential to facilitate the formation of carbon-based "polymers," which are known as organic compounds and even the constituent elements of DNA.
Lead author William Rapin of the French Institute of Astrophysics and Planetology said this is "the first conclusive evidence" we have seen that the ancient climate of Mars had this regular, Earth-like cycle of dry and wet.
These peculiar cracks suggest that Mars once had a seasonal dry-wet cycle that allowed microbes to survive.
What's more, he says, the dry-wet cycle is helpful, and even necessary, for the evolution of molecules that could lead to life.
Curiosity launched in 2011 from Cape Canaveral in Florida, USA, on a two-year mission that aims to gather information on whether Mars can support life.
Two years ago, the rover climbed the 4,828-meter-high Sharp Mountain and found cracks in the soil.
The cracks were discovered on the site of an ancient lake, sandwiched between a layer of sediments rich in clay and a layer of sulfites with a higher salt content.
The contrasting sedimentary layers suggest that there was a dry-wet cycle, as clay is usually produced in humid environments, while sulfites usually form after water dries up.
Scientists believe that unusual cracks were also formed in this process, changing from a dry "T-junction" to a hexagonal shape due to the influence of water.
In addition, long chains of carbon-based molecules known as "polymers" may have formed, which are known to be the chemical constituent elements of life.
In 2017, a similar crack was found on a nearby rock known as the "Old Bubble."
Mars was much cooler 3.6 billion years ago than it is now, favoring the flow of liquid water.
It's unclear why these cycles stopped, but some scientists believe that Mars was much cooler then than it is now, favoring the flow of liquid water.
Ashwin Vasavada of NASA's Jet Propulsion Laboratory (JPL) in Southern California said the paper expands on the variety of Curiosity discoveries.
He said that in 11 years, the rover has found a lot of evidence that ancient Mars may have bred microbial life. Now, the mission has uncovered evidence of conditions that may have contributed to the origin of life.
Unlike Earth, Mars does not have any tectonic plates, which means that ancient sediments are not buried far below the surface, but are fairly well preserved on the surface.
Therefore, scientists believe that more in-depth research can be carried out on the prehistoric biology and geology of Mars.
Lapin said we are very fortunate to have a planet like Mars near Earth, which still retains memories of the natural processes that may have led to the birth of life.
Text/Nandu reporter Chen Lin