China’s Mars Zhurong rover finds an ocean shoreline on the Red Planet

The Chinese Mars rover Zhurong is adding an exciting twist to the story and history of water on Mars.

After landing in southern Utopia Planitia on Mars in May 2021, the now-defunct Zhurong rover went to work exploring the Martian surface, and its latest findings might just change the way we think about the Red Planet.

Bo Wu and a team of researchers from Hong Kong Polytechnic University believe they’ve found compelling evidence of an ocean shoreline for a massive body of water that once covered Mars’ northern lowlands.

What is the Zhurong Mars rover?

The Zhurong rover is China’s first foray into Martian exploration, landing successfully on Mars in May 2021 as part of the Tianwen-1 mission.

Weighing around 240 kilograms (530 lbs) — about the size of a small car — Zhurong is packed with scientific instruments, including navigation and topography cameras, a multispectral camera for analyzing surface materials, and a ground-penetrating radar that can probe up to 100 meters beneath the surface.

These tools allow Zhurong to capture detailed images, study the composition of rocks and soil, and investigate the planet’s subsurface structures.

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What sets Zhurong apart is its ability to study Mars both above and below ground. The ground-penetrating radar is particularly exciting because it helps scientists search for signs of water ice and understand the geological layers hidden beneath the surface

The rover also carries instruments to examine Mars’ magnetic field and atmospheric conditions, contributing valuable data to our understanding of the planet’s climate and potential for habitability.

Zhurong sees water-related features on Mars

For years, scientists have pondered the possibility of a vast ocean on Mars, especially during the Hesperian period about 3.7 billion years ago. Concrete proof, however, has been hard to come by.

Using a mix of Zhurong’s onboard cameras and ground-penetrating radar, plus remote sensing data from orbiting satellites, the team identified several intriguing water-related features around the rover’s landing area.

The Zhurong landing site (red cross) shown on the geologic map by Tanaka et al. Regions of different colors indicate different geologic units. The red box shows the study area, covering an area of ~ 1800 km × 800 km. The thick black line is the Deuteronilus contact indicating a possible shoreline across the region. The background map is a shaded relief of the MOLA topography.

Since touching down, Zhurong has traveled about 1.2 miles, studying the geology of its surroundings in search of signs of water or ice.

The features spotted include crater-like pitted cones, troughs, sediment channels, and mud volcano formations. If that sounds like the remnants of a beachfront, you’re onto something.

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According to Bo Wu and his colleagues, these formations are consistent with what you’d expect to find in a nearshore zone, suggesting this area was once a coastline.

Dating the Martian ocean

Based on the composition of surface deposits, the team estimates that the ocean likely existed around 3.68 billion years ago.

The water was heavily silted, forming the layering structure of the deposits,” study co-author Sergey Krasilnikov of the Hong Kong Polytechnic University told Reuters.

This silt-laden water would have created distinct sedimentary layers, much like those found in ancient seabeds on Earth.

Interestingly, the researchers propose that after forming, the ocean froze over for about 10,000 to 100,000 years — a mere blink in geological terms.

This freezing period etched out the coastline features observed today before the ocean eventually dried up roughly 260 million years later. Imagine a vast frozen ocean, sitting quietly on Mars, waiting for its turn to disappear.

Not everyone agrees

However, not everyone is jumping on the bandwagon.

Benjamin Cardenas of Pennsylvania State University points out that erosion over billions of years would likely have erased such delicate features. It’s a fair concern — Mars isn’t exactly a place where things stay preserved forever.

Wu acknowledges this skepticism but suggests that asteroid impacts might have resurfaced portions of the shoreline, making them detectable today.

Implications for Martian life

So, what does all this mean in the grand scheme of things? Well, the presence of an ancient ocean has profound implications for our understanding of Mars.

Water is a key ingredient for life as we know it. If Mars had oceans, could it have also hosted life? It’s a tantalizing thought that keeps scientists up at night.

NASA’s Insight Lander

Adding another layer to the mystery, NASA’s Insight lander found that a significant amount of water had seeped into Mars’s crust

“At least we have identified a place that should, in principle, be able to sustain life,” Michael Manga of the University of California, one of the study authors, said in a previous statement.

This underground water could have provided a stable environment for life to develop.

What’s next for Zhurong and Mars water?

But here’s the kicker: to get definitive answers, we need to bring Martian samples back to Earth for detailed analysis.

China’s Tianwen 3 Mars sample return mission aims to do just that by 2031, potentially beating NASA’s own sample return mission to the punch.

If all goes according to plan, we’ll have pieces of Mars right here on Earth in less than a decade.

As we await these missions, Zhurong continues to send valuable data, inching us closer to understanding the Red Planet’s watery past.

Could Mars have been teeming with life billions of years ago? It’s the million-dollar question. Only time — and more research — will tell.

The full study was published in the journal Scientific Reports.

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