It forms the second geologic period of the Neoproterozoic Era, preceded by the Tonian Period and followed by the Ediacaran. How did Venus descend into this hellish state? And how did its sister planet, Earth, manage to survive? “ĭid you know the Earth was allegedly a frozen ice ball at one time ? see the Wikipedia article: The Cryogenian is a geologic period that lasted from 720 to 635 million years ago. From floating bases stationed high in Venus’ atmosphere, they hope to send down new generation probes to search for clues from a time when the planet was alive. They are now unveiling daring new strategies to reach down to its hostile surface. Scientists have come to see Venus as the alien planet “next door,” a laboratory for testing ideas about how planets evolve and the challenges they face in nurturing life. Its burned-out surface is a global fossil of volcanic destruction, shrouded in a dense, toxic atmosphere. It’s a planet knocked upside down and turned inside out. Today, Venus spins slowly in a backward direction. Speaking about Venus, I just watch this video ” Venus Death of a Planet ” it says the entire planet is marked by volcanos and we could eventually have floating cities 25 km above the surface ? The caption reads : ” Billions of years ago, our nearest planetary neighbor, Venus, may have harbored lakes, oceans, and life-giving habitats similar to those on the early Earth. Goncharov, Nobuyoshi Miyajima, Daisuke Yamazaki and Nicholas Holtgrewe, 8 December 2021, Earth and Planetary Science Letters. Reference: “Radiative thermal conductivity of single-crystal bridgmanite at the core-mantle boundary with implications for thermal evolution of the Earth” by Motohiko Murakami, Alexander F. Moreover, scientists need to clarify how the decay of radioactive elements in the Earth’s interior – one of the main sources of heat – affects the dynamics of the mantle. “We still don’t know enough about these kinds of events to pin down their timing.” To do that calls first for a better understanding of how mantle convection works in spatial and temporal terms. However, he cannot say how long it will take, for example, for convection currents in the mantle to stop. They suggest that Earth, like the other rocky planets Mercury and Mars, is cooling and becoming inactive much faster than expected,” Murakami explains. “Our results could give us a new perspective on the evolution of the Earth’s dynamics. But as soon as post-perovskite appears at the core-mantle boundary and begins to dominate, the cooling of the mantle might indeed accelerate even further, the researchers estimate, since this mineral conducts heat even more efficiently than bridgmanite. When it cools, bridgmanite turns into the mineral post-perovskite. Murakami and his colleagues have also shown that rapid cooling of the mantle will change the stable mineral phases at the core-mantle boundary. This may cause plate tectonics, which is kept going by the convective motions of the mantle, to decelerate faster than researchers were expecting based on previous heat conduction values. Greater heat flow, in turn, increases mantle convection and accelerates the cooling of the Earth. This suggests that the heat flow from the core into the mantle is also higher than previously thought. “This measurement system let us show that the thermal conductivity of bridgmanite is about 1.5 times higher than assumed,” Murakami says. Measuring device for determining the thermal conductivity of bridgmanite under high pressure and extreme temperature. For the measurements, they used a recently developed optical absorption measurement system in a diamond unit heated with a pulsed laser. Now, ETH Professor Motohiko Murakami and his colleagues from Carnegie Institution for Science have developed a sophisticated measuring system that enables them to measure the thermal conductivity of bridgmanite in the laboratory, under the pressure and temperature conditions that prevail inside the Earth. However, researchers have a hard time estimating how much heat this mineral conducts from the Earth’s core to the mantle because experimental verification is very difficult. The boundary layer is formed mainly of the mineral bridgmanite. The temperature gradient between the two layers is very steep, so there is potentially a lot of heat flowing here. This boundary layer is relevant because it is here that the viscous rock of the Earth’s mantle is in direct contact with the hot iron-nickel melt of the planet’s outer core. One possible answer may lie in the thermal conductivity of the minerals that form the boundary between the Earth’s core and mantle. Still unanswered, though, are the questions of how fast the Earth cooled and how long it might take for this ongoing cooling to bring the aforementioned heat-driven processes to a halt.
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