Wave 'ripples' found on Mars prove it once had flowing liquid water, not just ice

The existence of water on Mars has long been a subject of curiosity and debate. A recently published study presents compelling evidence of ancient “wave ripples” in rocks that were shaped by Martian water and winds billions of years ago.

These ripples, imprinted on the Martian surface, speak to a time when shallow bodies of water were open to the Martian air.

Mysterious ripples on Mars

The importance of these ripples cannot be overemphasized as they provide clear evidence of the existence of a standing body of water on Mars approximately 3.7 billion years ago.

This profound discovery paints a picture of a time when the Martian climate was seemingly warm enough to support liquid bodies water, not just frozen ice fields, that were open to the air.

“The shape of the ripples could only have been formed under water that was open to the atmosphere and acted upon by wind,” observed Claire Mondro, a postdoctoral scholar from The California Institute of Technology (CalTech) and the study’s first author.

What the Mars ripples tell us

Dr. Michael Lamb, a geology professor at Caltech, painstakingly created computer models based on these ripples to estimate the size of the ancient Martian lake.

Lamb’s extensive experience in studying sediment, water, and atmosphere interactions on Earth lent credibility to this model.

The ripples, a mere 6 millimeters high and spaced 4 to 5 centimeters apart suggest the existence of a shallow lake, no deeper than about 2 meters (6.5 feet).

Mondro’s observations lend further weight to these inferences. “Extending the length of time that liquid water was present extends the possibilities for microbial habitability later into Mars’s history,” she pointed out.

Exploring the Martian surface

These marvelous ripples went unnoticed until NASA’s Curiosity rover documented them in 2022 during its expedition across the Gale Crater region of Mars, a region that was once home to wind-blown dunes.

A nearby band of rock, the Amapari Marker Band, hinted at the existence of another lake, approximately 6.5 feet (2 meters) deep, that formed slightly later in Mars’s history than the previous one.

Why do Mars ripples matter?

“The discovery of wave ripples is an important advance for Mars paleoclimate science,” noted John Grotzinger, the Harold Brown Professor of Geology at Caltech.

“The Curiosity rover discovered evidence for long-lived ancient lakes in 2014, and now, 10 years later, Curiosity has discovered ancient lakes that were free of ice, offering an important insight into the planet’s early climate,” added Grotzinger, a former project scientist for Curiosity’s Mars Science Laboratory (MSL) mission.

It seems we are just scratching the surface of understanding the red planet’s past, and with each discovery, we inch closer to unraveling the mysteries of Mars and its potential for supporting life.

Clues to Mars’ climate evolution

The discovery of these ancient ripples offers a crucial glimpse into Mars’s climate history, providing scientists with valuable data to reconstruct the environmental conditions that existed billions of years ago.

The presence of liquid water suggests that Mars once had a significantly thicker atmosphere that was capable of sustaining warmer temperatures.

Over time, the planet’s climate underwent drastic changes, leading to the loss of surface water and the thinning of its atmosphere.

Understanding these transitions is key to determining how long Mars could have supported habitable conditions and whether it might have once harbored microbial life.

Scientists believe that further exploration of ripple formations could shed light on the duration and stability of these ancient lakes, helping to piece together the timeline of Mars’ environmental shifts.

Implications for future Mars missions

The findings from Curiosity’s observations could play a pivotal role in shaping the objectives of upcoming Mars missions.

Future rovers and landers, equipped with more advanced instruments, may focus on analyzing ripple formations in greater detail, searching for chemical signatures that indicate past life-supporting conditions.

The Perseverance rover, currently exploring Jezero Crater, has already been tasked with collecting samples that might contain traces of ancient microbial activity.

These efforts align with NASA’s long-term goal of bringing Martian samples back to Earth for comprehensive laboratory analysis.

The ripple evidence on Mars is also encouraging for future crewed missions, as understanding past water sources could help identify potential locations for human exploration and resource utilization.

The full study was published in the journal Science Advances.

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