NASA’s Curiosity rover has encountered an extraordinary landscape while climbing through a Martian valley nicknamed “Valle Grande.” Images sent back by the rover show the ground covered with honeycomb-like patterns known as polygonal fractures, each measuring about 1.5 to 3 inches (4 to 8 centimeters) across.
Curiosity has seen small clusters of similar geometric shapes before, but never anything approaching the scale of the field now visible in Valle Grande.
A Sea of Polygons Across Mars
The full extent of the formations appears in a 360-degree panorama captured on June 19 and 20, during the 4,930th and 4,931st Martian days, or sols, of the mission. The polygons stretch across the terrain in every direction, continuing as far as the rover can see.
The patterns also climb the sides of a nearby butte nicknamed “Miraflores.” The formation rises 20 feet (6 meters) above the surrounding landscape and is capped by a thick layer of sand.
“We’ve seen a lot of fascinating landscapes through Curiosity’s eyes, but this sea of polygons took our breath away,” said the mission’s project scientist, Ashwin Vasavada of 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.”
What Created the Honeycomb Patterns?
Some polygonal formations previously examined by Curiosity clearly began as cracks in drying mud. However, several different processes can produce this kind of honeycomb appearance.
Repeated warming and cooling can fracture the ground into geometric shapes. Compression may also create similar patterns by forcing water out of sediment after the material becomes buried beneath the surface.
Scientists are now studying the newly discovered formations to determine which of these processes, or possibly a combination of them, shaped the landscape in Valle Grande.
Fourteen Years of Martian Surprises
The enormous polygon field is the latest in a long series of unexpected discoveries made by Curiosity since it landed on Mars 14 years ago, on Aug. 5, 2012.
During its journey, the rover has encountered sulfur crystals, reflective meteorites, and many other unusual geologic features. More importantly, Curiosity has transformed scientists’ understanding of ancient Mars by showing that the planet once possessed water, useful chemistry, and nutrients that could have supported microbial life.
Evidence of Mars’ Watery Past
Billions of years ago, lakes and streams were scattered across the lower foothills of Mount Sharp, a 3-mile-tall (5-kilometer-tall) mountain that Curiosity has been climbing since 2014.
The rover has found chemical traces left behind by this wetter period, including carbon-based molecules believed to be precursors to RNA and DNA, two nucleic acids that carry genetic information.
Scientists cannot determine whether those organic molecules were produced through biologic or geologic processes. Both explanations remain possible. Even so, the discovery confirmed once again that ancient Mars contained the chemical ingredients needed to support life.
Managed by Caltech in Pasadena, JPL built Curiosity and leads the mission on behalf of NASA’s Science Mission Directorate in Washington as part of the agency’s Mars Exploration Program portfolio.