Martian ‘spiderwebs’ revealed: Curiosity rover uncovers signs of long-lost groundwater

These small, rounded nodules formed from minerals deposited as ancient groundwater slowly evaporated on Mars billions of years ago. NASA’s Curiosity rover photographed the pea-sized features on 21 August 2025 while examining boxwork rock formations. (Image: NASA)

NASA’s Curiosity rover is examining unusual boxwork ridges on Mars’ Mount Sharp that resemble spiderwebs from orbit. The formations likely formed through ancient groundwater activity, suggesting water may have lasted longer than previously thought. Mineral findings, including clays and carbonates, support this theory, while organic molecule testing continues. The discovery could reshape understanding of Mars’ climate history and its potential to have supported microbial life billions of years ago.

Did our AI summary help?

NASA says its Curiosity rover is studying strange spiderweb-like ridges on Mars, offering fresh clues about ancient groundwater and possible past life.

Boxwork Ridges on Mount Sharp

For six months, the rover explored boxwork formations. These low ridges rise three to six feet. Sandy hollows stretch between the crisscrossing rocky lines. From orbit, they resemble giant spiderweb patterns. Scientists think groundwater once moved through fractures. Minerals likely hardened certain rock sections underground. Wind later eroded softer surrounding material away.

The region lies high on Mount Sharp. The mountain rises three miles above Gale Crater. Each layer records a changing ancient climate. Higher slopes show water gradually disappearing over time. Occasional wet periods brought rivers and lakes. Eventually Mars became the cold desert seen today.

Seeing boxwork so high surprised mission scientists. Tina Seeger of Rice University explained implications. A higher groundwater table must have existed. That suggests water lasted longer than expected. Longer water presence improves microbial survival chances.

Rover Challenges and Groundwater Evidence

Driving across ridges tested rover operations carefully. The vehicle weighs about 899 kilograms. It must cross narrow ridge tops precisely. Ashley Stroupe from NASA Jet Propulsion Laboratory described the terrain challenges. Slippery sand fills the hollows below. Engineers constantly adjust driving paths remotely.

Earlier orbital images showed dark central fractures. In 2014, scientists proposed groundwater seepage there. Close inspection confirmed those dark lines exist. Curiosity also spotted bumpy nodules nearby. Nodules indicate mineral-rich groundwater activity previously. Strangely, nodules avoided central fracture zones. Researchers still debate why distribution differs.

Rock Samples and Sulfate Layer Plans

Curiosity drilled three samples last year. One came from a ridge top. Another came from hollow bedrock areas. A third preceded the ridge field. X-ray analysis detected clay within ridge material. Carbonate minerals appeared inside hollow samples. These minerals support groundwater formation theories.

Recently, a fourth sample underwent wet chemistry. Heated rock powder reacted with chemical reagents. This method helps detect organic carbon compounds. Such molecules matter for life formation.

In March, the rover will depart boxwork. The area belongs to a sulfate-rich layer. Sulfates formed as Martian waters evaporated. The team will explore this layer further. Scientists hope to clarify climate shifts billions ago.