Discovery of cracked mud on Mars has alien hunters excited about finding life on the Red Planet

Martian fighters get excited by cracked mud on the Red Planet.

A new paper suggests that the same conditions that caused the cracks may have favored microbial life.

Scientists aren’t sure how life on Earth originated, but a prevailing theory says persistent cycles of wet and dry conditions on land helped assemble the complex chemical building blocks needed to start life.

Found by NASA’s Curiosity Mars rover is exciting for the mission’s team, they suggest Mars has endured cycles of wet and dry conditions – believed to be favorable for life

This is why a patchwork of well-preserved ancient mud cracks found by NASA’s Curiosity Mars rover is exciting for the mission’s team.

The Nature article describes how the distinctive hexagonal pattern of these mud cracks is the first evidence of wet-dry cycles occurring on early Mars.

“These particular mud cracks form when wet-dry conditions occur repeatedly — perhaps seasonally,” said the paper’s lead author, William Rapin of France’s Institut de Recherche en Astrophysique et Planétologie.

Curiosity gradually rises to the sedimentary layers of Mount Sharp, which stands 5 kilometers high in the Gale crater.

The rover spotted the mud cracks in 2021 after drilling a rock target sample nicknamed “Pontours,” found in a transition zone between a clay-rich layer and an upper layer enriched with salty minerals called sulfates.

While clay minerals usually form in water, sulfates tend to form when water dries.

Scientists now say they’ve found “sufficient evidence” that ancient Mars may have supported microbial life

The minerals found in each area reflect different eras in Gale Crater’s history. The transition zone between them provides a record of a period when long dry spells prevailed and the lakes and rivers that once filled the crater began to recede.

As mud dries out, it shrinks and breaks into T-shaped intersections — which Curiosity previously discovered at “Old Soaker,” a collection of mud cracks lower on Mount Sharp.

Those nodes are evidence that the Old Soaker mud once formed and dried out, while the recurrent exposure to water that created the Pontours mud caused the T-shaped nodes to soften and become Y-shaped, eventually forming a hexagonal pattern.

The hexagonal cracks in the transition zone continued to form even as new sediment was deposited, indicating that wet-dry conditions persisted for long periods. ChemCam, Curiosity’s precision laser instrument, confirmed a strong crust of sulfates along the margins of the cracks, which isn’t too surprising given the proximity of the sulfate region. The salt crust made the mud cracks resistant to erosion, preserving them for billions of years.

“This is the first tangible evidence we’ve seen that the ancient Martian climate had such regular, Earth-like wet-dry cycles,” Rapin said. “But more importantly, wet-dry cycles are useful—perhaps even required—for molecular evolution that could lead to life.”

While water is essential to life, a careful balance is needed – not too much water, not too little. The kinds of conditions that sustain microbial life, for example those that allow for a long-lasting lake, are not the same as the conditions that scientists believe are necessary to promote chemical reactions that can lead to life.

An important product of those chemical reactions are long chains of carbon-based molecules called polymers — including nucleic acids, molecules considered to be the chemical building blocks of life as we know it.

Wet-dry cycles control the concentration of chemicals that fuel the fundamental reactions that lead to the formation of polymers.

“This paper expands on the kinds of discoveries Curiosity has made,” said the mission’s project scientist, Ashwin Vasavada of NASA’s Jet Propulsion Laboratory in Southern California.

“For 11 years, we’ve found ample evidence that ancient Mars could have supported microbial life. Now the mission has found evidence of conditions that may also have favored the emergence of life.”

The discovery of the Pontours mud cracks may have given scientists the first chance to study the remains of the cauldron of life. Earth’s tectonic plates are constantly recycling the surface, burying examples of its prebiotic history. Mars has no tectonic plates, so much older periods of the planet’s history have been preserved.

“We are fortunate to have a planet like Mars nearby that still retains a reminder of the natural processes that may have led to life,” Rapin said.

Curiosity was built by NASA’s Jet Propulsion Laboratory, which is operated by Caltech in Pasadena, California. JPL is leading the mission on behalf of NASA’s Science Mission Directorate in Washington.