Curiosity Captures 11-Image Mars Panorama of 20-Foot Miraflores Butte

Q: If ancient mud cracks formed these strange polygons, what forced the water out of Mars' Valle Grande billions of years ago?

No one knows yet. If the Valle Grande polygons were ancient mud cracks, the water was most likely lost as Mars’ climate shifted from wetter conditions to the cold, thin-atmosphere world seen today, causing surface water to evaporate, freeze, or retreat underground. What Curiosity has found does not by itself identify a single trigger. NASA scientists say several processes could explain the honeycomb-like fractures: drying mud, repeated heating and cooling, or compression in buried sediments that physically squeezed water out. The “forced out” idea fits the burial scenario, where accumulating layers above wet sediment increased pressure and expelled pore water. The broader geological record at Gale Crater shows that billions of years ago the area hosted lakes and streams, and possibly an ancient seabed. In that setting, mud cracks would imply wet sediment later dried during recurring wet-dry cycles. Earlier Curiosity findings of hexagonal mud cracks elsewhere in Gale Crater have already been interpreted as evidence that water did not disappear all at once, but likely fluctuated over time as lakes shrank and returned. So the best current answer is that Valle Grande’s water may have been removed by drying linked to long-term climate change, or by later burial and compaction of sediment, or by some combination of both. Curiosity’s measurements of the polygons’ shape and chemistry are intended to distinguish between those possibilities.

2 articles · Updated · PetaPixel · Aug 4

11 Mastcam photos taken on June 11 were stitched into a 6,162-by-2,576 panorama showing the sand-capped “Miraflores” butte inside Gale Crater.
The roughly 20-foot butte appears to be an erosional remnant, left standing as surrounding rock wore away and deepened the valley Curiosity is climbing.
Thousands of 4-to-8-centimeter polygons surround the butte on terrain scientists think was once an ancient seabed, a pattern NASA says could hold clues to how the features formed.
Gale Crater’s lower Mount Sharp foothills preserve evidence of Mars’ watery past, where Curiosity has been ascending since 2014 and has already found organic chemistry linked to habitable conditions.