Curiosity rover discovers vast 'sea of polygons' on Mars, revealing clues to ancient watery past

In mid-June, as NASA's Curiosity rover climbed into a Martian valley called Valle Grande, its cameras captured something that stopped the mission team in their tracks: a landscape carpeted with geometric rock patterns, honeycomb-like formations stretching to the horizon in every direction. The rover had seen polygonal fractures before—small patches scattered across the Martian surface. But this was different. This was vast.

The patterns, which scientists call polygonal fractures, appeared in a 360-degree panorama taken on June 19 and 20. They wrapped around a 20-foot-tall rock formation the team had nicknamed Miraflores, and they extended as far as the rover's instruments could measure. Ashwin Vasavada, the project scientist overseeing Curiosity's work, described the moment with genuine wonder: the sheer scale of what they were seeing suggested something significant about how Mars' surface had been shaped over billions of years.

What makes these patterns important is not their beauty, though they are striking. It is what they might reveal about Mars' past. Scientists have several theories about how such formations develop. Some polygonal patterns form when mud dries and cracks, much like the parched earth you might see in a dried riverbed on Earth. Others emerge from repeated cycles of heating and cooling, or from the compression of buried sediment that forces water out of the rock layers. Each mechanism tells a different story about the conditions that existed when the patterns formed.

Curiosity has been gathering evidence about Mars' ancient environment since it landed in August 2012. The rover has found sulphur crystals, meteorites, and chemical signatures that point to a very different world than the cold, dry desert that exists today. Most significantly, the rover has confirmed that billions of years ago, the lower slopes of Mount Sharp—the massive peak at the center of Gale Crater where Curiosity operates—were dotted with lakes and streams. Water flowed across the surface. The ground held moisture.

Since beginning its climb up Mount Sharp in 2014, Curiosity has detected carbon-based molecules in the rock layers it has sampled—compounds that form the backbone of RNA and DNA. These are not signs of life itself, at least not definitively. Scientists cannot yet say whether these molecules were created by living organisms or through purely chemical processes. But their presence matters. It means that ancient Mars possessed the chemical building blocks and the environmental conditions—liquid water, organic compounds, chemical energy—that life as we understand it would need to emerge and persist.

The discovery of this vast field of polygonal fractures adds another piece to that picture. If these patterns formed through the drying of ancient mud, they are a direct imprint of water that once saturated the Martian surface. If they formed through thermal cycling or sediment compression, they still speak to an active, dynamic geology shaped by processes that require moisture and movement. Either way, they reinforce what Curiosity has been telling us for over a decade: Mars was not always the barren world we see today. It was a place where water existed, where chemistry was complex, where the conditions for life—at least as we define it—were present.

The rover continues its slow climb up Mount Sharp, measuring and analyzing as it goes. Each discovery narrows the gap between what we know and what we still need to understand about whether Mars ever harbored life, and what happened to make it the world it is now.