Mars InSight photos: A timeline to landing on the Red Planet Instead, the fractures may have formed before the rock was exposed, by the hydraulic pressure of water in its cracks or they may be a result of thermal stress caused by the seasonal variations in temperature on the planet's surface. Internet speculation has raised the possibility that the small door-shaped cave may have been caused by a seismic "Marsquake" – two of the largest Marsquakes ever recorded, for example, happened late in 2021.īut Mangold is cool on the idea: "The whole mountain is seriously fractured, there's no need of big Marsquakes," he said. "These are fractures in two directions, creating an 'open box' with a door appearance – nothing artificial," Mangold said. Mangold, who studies geological data from the Curiosity and Perseverance rovers, agrees that the Martian "door" has been created naturally by the structure of the rock. Two of the largest quakes recorded on Mars happened at the Valles Marineris, a network of canyons, shown here in this color image. Several natural vertical fractures are also visible in the image, among them fractures caused by the way rocks weather on Mars and the small cave or "door" seems to have formed where the vertical fractures intersect with the strata, he said. Martian winds have eroded the strata since they've become exposed on the surface, and the images even show traces of them inside the "door," he said. "They were deposited perhaps 4 billion years ago under sedimentary conditions, possibly in a river (I'd need to see more of the outcrop to be sure) or a wind-blown dune." "These are silt beds, with harder sandy beds that stand out," he told Live Science in an email. Rocky layers called strata can be seen on the rock, dipping on the left and higher at the right. Hodgson, a vice president at the British geoscience firm Searcher, thinks the "door" is caused by erosion. (Image credit: NASA/JPL-Caltech/MSSS) Mars erodes Another intriguing sight on Mars: This photo shows a "mineral flower" alongside other diagenetic features on the surface of Mars captured by NASA's Curiosity rover on Feb.
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