The salty crust is what made the mud cracks resistant to erosion, preserving them for billions of years. ChemCam, Curiosity’s precision laser instrument, confirmed a hardy crust of sulfates along the cracks’ edges, which isn’t too surprising given the proximity of the sulfate region. The hexagonal cracks in the transitional zone kept forming even as new sediment was deposited, indicating that the wet-dry conditions continued over long periods of time.
Those junctions are evidence that Old Soaker’s mud formed and dried out once, while the recurring exposures to water that created the Pontours mud caused the T-shaped junctions to soften and become Y-shaped, eventually forming a hexagonal pattern. The transitional zone between them offers a record of a period when long dry spells became prevalent and the lakes and rivers that once filled the crater began to recede.Īs mud dries out, it shrinks and fractures into T-shaped junctions – which are what Curiosity discovered previously at “ Old Soaker,” a collection of mud cracks lower down on Mount Sharp. The minerals prevalent in each area reflect different eras in Gale Crater’s history. While clay minerals usually form in water, sulfates tend to form as water dries up. The rover spotted the mud cracks in 2021 after drilling a sample from a rock target nicknamed “Pontours,” found within a transitional zone between a clay-rich layer and one higher up that is enriched with salty minerals called sulfates.
#NASA IMAGES FROM MARS ROVER DOWNLOAD#
Download image ›Ĭuriosity is gradually ascending the sedimentary layers of Mount Sharp, which stands 3 miles (5 kilometers) high in Gale Crater. Curiosity Views Mud Cracks in the Clay-Sulfate Transition Region: A close-up of the panorama taken by Curiosity’s Mastcam at “Pontours” reveals hexagonal patterns – outlined in red in the same image, right – that suggest these mud cracks formed after many wet-dry cycles occurring over years.
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