Curiosity has discovered a ‘sea’ of mysterious polygons on Mars — scientists do not know how they came to be

Curiosity has already encountered similar geometric structures in Gale Crater, and some of them turned out to be ancient mud cracks associated with water. But at this new location, the team has seen such an extensive field for the first time. And crucially, scientists do not yet know exactly what created these polygons.

Details

The unusual site is located in a valley that the mission team has unofficially named Valle Grande, on the slopes of Mount Sharp in Gale Crater.

Curiosity captured a 360-degree panorama on 19 and 20 June 2026 – on the 4,930th and 4,931st Martian days of its mission. In the images, polygonal structures cover the surface in all directions and even wrap around the small, approximately 6-metre-high Miraflores hill.

Ashwin Vasavada, Curiosity’s science programme lead, described what they saw as a ‘sea of polygons’. He said that over the years, the rover had revealed many unusual landscapes to researchers, but the team had never before seen such a large number of these structures in one place.

NASA has not yet specified the exact area of the field. Therefore, this is not a proven giant expanse covering tens or hundreds of square kilometres, but rather an area that appears exceptionally vast from the rover’s vantage point.

The new landscape looks particularly strange up close.

The surface is criss-crossed by protruding lines that interconnect and divide the ground into distinct geometric cells. NASA estimates the typical size of these polygons to be approximately 4–8 centimetres. Panoramic images also reveal structures measuring around 5–10 centimetres.

This fundamentally distinguishes the discovery from the vast Martian polygons that can be observed from orbit.

Here, we are talking about centimetre-scale surface texture — which is precisely why a ground-based rover is particularly useful. Curiosity can drive right up close to such formations, photograph the details and analyse the chemical composition of the rocks.

The most intriguing theory regarding the origin of the ‘honeycombs’ involves water.

On Earth, similar polygonal cracks are a familiar sight in dried mud: wet sediment loses water, shrinks in volume and cracks into geometric fragments.

Curiosity has already found structures on Mars for which this explanation has been confirmed much more conclusively.

In 2023, researchers described centimetre-scale polygonal ridges in Gale Crater in the journal *Nature*. Their cracks were connected by characteristic Y-shaped junctions and were enriched with sulphates. Analysis showed that the sediment had likely become wet and dried out repeatedly, rather than having undergone a single drying episode.

The authors linked these structures to a transitional period approximately 3.8–3.6 billion years ago, when Mars’s climate may have included sustained cycles of wet and dry conditions — possibly even seasonal ones.

This is precisely why any new field of polygons in Gale Crater immediately raises the question: might there be another record of ancient water preserved here?

The answer remains unknown for now.

NASA specifically emphasises that similar geometries can arise for various reasons. Some polygons previously investigated by Curiosity were indeed mud cracks, but this explanation cannot automatically be applied to Valle Grande.

A polygonal surface may form as a result of repeated cycles of heating and cooling. Another possibility is the compaction of buried sediments, where pressure forces water out of them. Cracks may also form due to water loss or changes in minerals after the layer has already formed.

In other words, ‘honeycombs’ that look similar on the surface may have completely different geological histories.

To get to the bottom of this, scientists have measured the shape of the new polygons and are analysing their chemical composition. Vasawada hopes that it is precisely this combination of geometry and chemistry that will help us understand the formation mechanism.

Why this is important

This is not the first time Curiosity has discovered polygons on Mars.

NASA explicitly states that, in previous years, the rover has encountered small areas with similar geometric structures on several occasions. What makes Valle Grande distinctive is this: never before has the Curiosity team seen so many polygons in one place.

Therefore, the statement ‘the rover has discovered polygons on Mars for the first time’ would be incorrect.

It would be more accurate to say that this is the first time it has encountered such an extensive field of small polygonal cracks.

This explains both why the images aroused such interest amongst the team and why scientists are not yet in a hurry to declare the origin of the discovery as established.

If it is dried mud, the discovery could provide insights into Mars’s most recent wet periods

Gale Crater is of particular interest to scientists precisely because it has preserved a long geological history of changes in the Martian climate.

Curiosity has already uncovered plenty of evidence that lake and river conditions existed here billions of years ago. But gradually, Mars became colder and drier, and stable liquid water disappeared from the surface.

The age and origin of this new field are therefore of great significance.

If the Valle Grande polygons did indeed form as a result of the wet soil drying out repeatedly, they may preserve information about one of the stages in the transition from the wetter ancient Mars to the modern desert planet.

If, however, the cracks appeared much later — for example, as a result of temperature cycles or changes in already solidified rock — they would tell a completely different chapter of the story.

For now, scientists are unable to decide between these scenarios.

The 2023 findings have attracted particular interest not only amongst geologists.

Recurring ‘wet–dry–wet again’ cycles are considered potentially important for prebiotic chemistry. On Earth, such cycles are capable of concentrating substances and facilitating reactions in which small organic molecules combine to form more complex structures.

The authors of the study in *Nature* therefore suggested that the relevant conditions in the ancient Gale Crater may have been favourable for certain processes of chemical evolution preceding the emergence of life.

However, it does not follow from this that Curiosity has discovered life or even traces of it.

Nor can it yet be claimed that the new Valle Grande field existed under the same wet-dry conditions. First, the mechanism behind the formation of its cracks must be established.

Why is Mars capable of preserving such structures for billions of years?

On Earth, ancient surfaces are constantly reshaped by erosion, water and the movement of lithospheric plates.

Modern-day Mars lacks Earth’s system of plate tectonics and sustained flows of liquid water on the surface. Consequently, many ancient sedimentary structures are able to persist for exceptionally long periods.

This turns Gale Crater into a unique geological archive.

Layer by layer, Curiosity climbs Mount Sharp and examines rocks formed during different periods. Their minerals, texture and fractures allow us to reconstruct environmental changes that took place billions of years ago.

New sites may turn out to be the next page in this archive – but for now, scientists do not yet know exactly what is recorded on it.

The rover’s advantage is that researchers do not have to draw conclusions based solely on photographs taken from orbit.

Curiosity is situated right amongst the polygons and is able to compare different areas, measure their geometry and determine the chemical composition of the rocks.

It is precisely this data that should now reveal whether the new structures show signs of water exposure or arose as a result of some other process.

Therefore, for the time being, the ‘sea of polygons’ is more accurately regarded as a new geological mystery rather than definitive proof of an ancient, wet Mars.

What is known for certain so far is this: Curiosity has discovered in Valle Grande a cluster of small polygonal structures, several centimetres in size, the likes of which have not been seen before on this mission. Some similar formations on Mars were indeed created by water, but scientists are still trying to determine the mechanism behind the formation of this particular vast field.

Source

NASA announced the discovery on 29 July 2026. The field was discovered by the Curiosity rover in Valle Grande on the slopes of Mount Sharp in Gale Crater. The panorama was captured on 19–20 June 2026, on sol 4930 and 4931 of the mission. The typical size of individual polygonal structures is around 4–8 cm.

Main source: NASA Jet Propulsion Laboratory,“NASA’s Curiosity Mars Rover Discovers Field of Honeycomb Textures”, 29 July 2026.