The Spiders of Mars! This phrase describes both David Bowie’s guidance group in the 1970s, and a peculiar function on Mars that has nothing else on earth. But we are here to discuss the latter, because scientists have experimental evidence of how it is formed.
In a paper published in Scientific Reports, researchers simulated the state of the Marspool and found a process that creates araneiforms, the spider-like feature seen in many orbiting observations of the Red Planet. The team tested the so-called Kieffer hypothesis for their formation consistent with incredible observations of the past decade. And now it can be faithfully recreated in the lab.
Mars is much cooler than Earth, and its atmosphere is composed mostly of carbon dioxide. In winter, at the poles, it freezes from the air on the ground and in spring it sublimes – it goes straight from solid to gas. What the team has seen is that this sublimation is not from bottom to bottom, but from bottom to top.
Sunlight penetrates the transparent ice and warms the ground beneath it. The ice layer will begin to sublimate closer to the site until the outer layer of ice cannot handle the pressure and cracks, creating the peculiar pattern in which the sandy / dusty material of Mars will be deposited as a plume.
‘This research provides the first set of empirical evidence for a surface process that could presumably alter the polar landscape on Mars. Kieffer’s hypothesis has been accepted for more than a decade, but until now it has been set in a purely theoretical context, ”said lead author Dr Lauren McKeown of the Open University.
“The experiments directly show that the spider patterns we observe on Mars’ orbit can be carved by the direct conversion of dry ice from solid to gas. This is exciting because we are beginning to understand more about how the surface of Mars is seasonal today. change. ”Dr McKeown continues.
The team took an ingenious approach to testing it. They used a vacuum chamber to recreate the very low Martian pressure. They hung a perforated block of dry ice (frozen carbon dioxide) on a mechanical arm and lowered it to simulated soils of grains of different sizes.
By being the warmer ground, the block became sublime, with the material being lifted by the freshly liberated gas in a plume through the middle hole of the block. After the block was removed, an araneiform structure was left on the ground. The finer the soil, the more branching the pattern.
“This innovative work supports the emerging theme that the current climate and weather on Mars have a significant impact not only on dynamic surface processes, but also for any future robotic and / or human exploration of the planet,” said co-author Dr Mary Bourke explains. , from Trinity College Dublin.
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