The surface of Mars is dotted with tiny geometric shapes that look just like a honeycomb, and scientists are marveling at the sight. NASA's Curiosity rover has discovered a vast field of these honeycomb-like patterns while climbing through a Martian valley nicknamed "Valle Grande." Each hexagon-shaped pattern measures roughly 1.5 to 3 inches (4 to 8 centimeters) across, about the size of a large grape. The polygons stretch as far as the rover can see in every direction, covering the ground like an endless mosaic.
The discovery was made on June 19 and 20, during the 4,930th and 4,931st Martian days of the mission. Curiosity captured a 360-degree panorama showing the patterns continuing across the terrain and even climbing the sides of a nearby butte called "Miraflores." That formation rises 20 feet (6 meters) above the surrounding landscape and is capped by a thick layer of sand.
Curiosity has seen small clusters of similar geometric shapes before, but nothing approaching this scale. "We've seen a lot of fascinating landscapes through Curiosity's eyes, but this sea of polygons took our breath away," said Ashwin Vasavada, the mission's project scientist at NASA's Jet Propulsion Laboratory in Southern California. "We measured their shapes and chemistry carefully and are hopeful there are clues in the data as to how these features formed."
Scientists are now working to understand what created these patterns. Some polygonal shapes on Mars began as cracks in ancient mud that dried up billions of years ago. But other processes can create similar honeycomb appearances, including repeated cycles of warming and cooling that fracture the ground, or compression that forces water out of buried sediment. Researchers hope the new data will reveal which process, or combination of processes, shaped Valle Grande.
This discovery is just the latest surprise from a rover that has been exploring Mars for 14 years now. Curiosity landed on August 5, 2012, and has transformed scientists' understanding of ancient Mars. Along the way, it has found sulfur crystals, reflective meteorites, and many other unusual features. Most importantly, Curiosity has shown that Mars once had water, useful chemistry, and nutrients that could have supported microbial life.
Billions of years ago, lakes and streams covered the lower foothills of Mount Sharp, a mountain that rises 3 miles (5 kilometers) into the Martian sky and that Curiosity has been climbing since 2014. The rover has detected carbon-based molecules believed to be precursors to RNA and DNA, the molecules that carry genetic information in all living things on Earth. Scientists cannot yet tell whether those molecules came from living organisms or from natural geologic processes, but their presence confirms that ancient Mars contained the basic chemical ingredients for life.