New findings from China’s Zhurong rover reshape our understanding of Martian water history
A vast ocean on the red planet
Recent discoveries from China’s Zhurong rover have provided compelling evidence that a massive ocean may have covered up to one-third of Mars around 3.7 billion years ago. The rover, which landed in the Utopia Planitia region in May 2021, has uncovered geological formations that strongly suggest the presence of an ancient shoreline. These findings offer critical insights into Mars’ past and its potential to have supported liquid water.
Tracing the Martian shoreline
Zhurong’s exploration of the southern part of Utopia Planitia, a vast plain in Mars’ northern hemisphere, has revealed several geological features consistent with past water activity, including:
- Coastal sediment deposits – Layered rock formations that resemble those found in dried-up lakes and shorelines on Earth.
- Troughs and channels – Structures that indicate ancient water flow, similar to river deltas or estuaries.
- Mud volcanoes – Evidence of subsurface water mixing with sediments and erupting to the surface, a process often seen in terrestrial coastal regions.
These findings align with previous orbital observations and reinforce the long-held hypothesis that a vast ocean once existed in Mars’ northern lowlands.
The rise and fall of a Martian sea
By analyzing both surface and orbital data, scientists have pieced together a timeline for this ancient ocean:
- Formation (~3.68 billion years ago) – The ocean likely emerged during a period when Mars had a thicker atmosphere and a stable climate, allowing liquid water to exist on the surface.
- Freezing and retreat (~3.5 billion years ago) – As Mars lost its atmosphere, temperatures dropped, causing the ocean to freeze and begin evaporating.
- Final disappearance (~3.42 billion years ago) – Over time, the remaining water either sublimated into space or was absorbed into the planet’s crust, leaving behind the barren landscape seen today.
This dramatic transformation highlights how Mars shifted from a once-wet world to the cold, dry desert we see now.
What this means for life on Mars
The presence of such a large body of water raises critical questions about Mars’ past habitability. Coastal environments, where land and water interact, are prime locations for the development of microbial life. If Mars once had an ocean, it may have also hosted conditions suitable for life billions of years ago.
Zhurong’s findings suggest that sedimentary layers in Utopia Planitia could contain preserved evidence of ancient life—if it ever existed. Further analysis of these formations will be crucial in the search for biosignatures.
The next steps in exploration
While these discoveries provide strong evidence for an ancient Martian ocean, definitive proof will require further exploration. Future missions aim to:
- Retrieve Martian rock samples – Bringing samples back to Earth for laboratory analysis will allow scientists to study sediment layers and search for chemical markers of past life.
- Analyze climate evolution – Understanding how and why Mars lost its water can offer insights into planetary climate change and habitability.
Zhurong’s discoveries mark a significant milestone in our exploration of Mars, shedding light on its complex history and bringing us closer to answering one of science’s most profound questions: Did life ever exist beyond Earth?
