(ORDO NEWS) — The USSR mission Venera-9 landed on Venus on October 22, 1975. The spacecraft lasted only 53 minutes in the harsh conditions of this planet.
However, he was able to transmit invaluable data on clouds, illumination, temperature and the chemical composition of the atmosphere, and also managed to make the first image in the history of mankind of the surface of another planet.
The atmosphere of Venus, the densest and hottest of the four terrestrial planets, is made up primarily of carbon dioxide, which has a pressure at the surface about 92 times the atmospheric pressure at sea level on Earth.
The average temperature of the planet is about 464 degrees Celsius. The planet is also enveloped in dense clouds of sulfuric acid.
One of the things Venus and Earth have in common is that Venus also releases internal heat into space. Geologists know that plate tectonics causes internal heat loss on the Earth. Heat radiates where the plates move apart. But little is known about the internal dynamics of Venus.
Researchers at the Jet Propulsion Laboratory (JPL) in Pasadena analyzed data collected by the Magellan spacecraft in the 1990s to calculate the thickness of the crust on Venus.
Their results show that, despite completely different characters, the Earth and Venus have a comparable heat flow and the same thickness of the lithosphere.
Earth has moving tectonic plates that slide, crash into each other, and separate, contributing to efficient heat loss.
Previous models suggested that Venus had either a lithospheric situation with a “stagnant lid” (a mostly immobile, cold lithosphere covering the entire planet) or an “episodic lid” (an unstable stagnant lid occasionally erupts with tectonic activity).
But more recent models and data analysis do not support these suggestions. Instead, the JPL researchers propose a “soft cap” model with active bowing of the lithosphere.
The researchers calculated the thickness of the lithosphere by measuring the curvature inside coronas – quasi-circular objects formed as a result of geological and volcanic activity.
Using Magellan altimetry data, they determined the average thickness of the lithosphere from 75 locations within 65 coronas: 11 ± 7 kilometers.
Based on this figure, they calculated the average heat flux from Venus, which exceeds the Earth’s average. However, its values are similar to those obtained in actively expanding tectonic areas.
The authors write: “Our analysis identifies likely areas of active expansion and suggests that Venus has a lithospheric thickness and global heat flow ranges similar to those of Earth.
Together with the geological history of the planet, our results support a soft-lid convective regime that relies on plumes, intrusive magmatism, and layering to increase heat flow.”
This is interesting because many researchers believe that plume-induced subduction is the cause of Earth’s plate tectonics, and thus Venus could have been Earth’s counterpart during the Archean period 4 to 2.5 billion years ago.
During that period, the Earth’s heat flux was about three times what it is today, and although the planet was covered in water, it was much hotter.
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