From orbit, the surface of Mars reveals... a giant spider web.
These structures, forming an extensive network of ridges, were created when underground water flowed through rock fractures, depositing minerals that hardened over time. Subsequently, the wind eroded the less resistant areas, leaving this lattice pattern in relief. This process, well-known on Earth on a small scale, takes on impressive dimensions on Mars, with ridges reaching up to 6.5 feet (two meters) high.
Scientists believe ancient groundwater formed this ridged web pattern, called boxwork, captured by NASA's Mars Reconnaissance Orbiter.
Credit: NASA/JPL-Caltech/University of Arizona
Exploring this rugged terrain is a major challenge for the Curiosity rover. Engineers must carefully guide this SUV-sized vehicle through ridges sometimes as narrow as itself. Driving through sandy hollows requires special attention to avoid getting stuck, but the team always finds appropriate solutions, as mission officials explain.
The presence of these "boxwork" features on the slopes of Mount Sharp, a 3.1-mile (five-kilometer) high mountain, indicates that the water table was once high. This situation implies that conditions favorable to life, related to the presence of liquid water, could have been maintained over an extended period, long after the disappearance of surface rivers and lakes.
Close-up observations have confirmed that the dark lines on the ridges are fractures, reinforcing the idea of water circulation. Small rounded nodules, associated with past water activity, have been found on the sides of the ridges and in the hollows, with no direct link to the central fractures, raising questions about their formation.
Curiosity has analyzed several rock samples in this region. The instruments have detected clay minerals on the ridges and carbonates in the hollows, confirming the action of water. The mission continues with the exploration of sulfate-rich layers, which formed as Mars gradually dried out. These investigations will help reconstruct the planet's climatic evolution billions of years ago.