Scientists re-create on Earth the sublimation of Mars’s winter mantle of dry ice
Click for original image.
Scientists have successfully re-created on Earth the process on Mars that creates the unique “spider” formations seen in the the Martian south pole region, produced when the winter mantle of dry ice begins to sublimate away into a gas.
The study confirms several formation processes described by what’s called the Kieffer model: Sunlight heats the soil when it shines through transparent slabs of carbon dioxide ice that built up on the Martian surface each winter. Being darker than the ice above it, the soil absorbs the heat and causes the ice closest to it to turn directly into carbon dioxide gas — without turning to liquid first — in a process called sublimation (the same process that sends clouds of “smoke” billowing up from dry ice). As the gas builds in pressure, the Martian ice cracks, allowing the gas to escape. As it seeps upward, the gas takes with it a stream of dark dust and sand from the soil that lands on the surface of the ice.
At the south pole, the ground below the mantle is stable enough that each winter the trapped CO2 gas follows the same path to the same points where the dry ice cracks, slowly creating “tributaries” that combine to form the spider formations.
The picture to the right, cropped, reduced, and sharpened to post here, comes from figure 9 of the paper [pdf]. It shows the lab-created spiders formed by this simulated process, thereby confirming this hypothesis about how the spiders form.
Click for original image.
Scientists have successfully re-created on Earth the process on Mars that creates the unique “spider” formations seen in the the Martian south pole region, produced when the winter mantle of dry ice begins to sublimate away into a gas.
The study confirms several formation processes described by what’s called the Kieffer model: Sunlight heats the soil when it shines through transparent slabs of carbon dioxide ice that built up on the Martian surface each winter. Being darker than the ice above it, the soil absorbs the heat and causes the ice closest to it to turn directly into carbon dioxide gas — without turning to liquid first — in a process called sublimation (the same process that sends clouds of “smoke” billowing up from dry ice). As the gas builds in pressure, the Martian ice cracks, allowing the gas to escape. As it seeps upward, the gas takes with it a stream of dark dust and sand from the soil that lands on the surface of the ice.
At the south pole, the ground below the mantle is stable enough that each winter the trapped CO2 gas follows the same path to the same points where the dry ice cracks, slowly creating “tributaries” that combine to form the spider formations.
The picture to the right, cropped, reduced, and sharpened to post here, comes from figure 9 of the paper [pdf]. It shows the lab-created spiders formed by this simulated process, thereby confirming this hypothesis about how the spiders form.
