"Coronary topography" on Venus may solve one of the biggest mysteries of "Earth's twin"
Earth and Venus are rocky planets with roughly the same size and rock chemistry, so they should lose their internal heat to space at about the same rate.
And while we know very well how the Earth loses its heat, the mechanism of heat flow for Venus, which is described as the “Earth’s evil brother” or “Earth’s evil twin”, due to its very extreme weather, was a mystery to scientists.
So a study using three decades of data from NASA's Magellan mission took a new look at how Venus cooled, and found that thin regions of the planet's upper layer may provide the answer.
The scientists studied a feature hundreds of miles wide called a "crown" or "crown" on the planet's surface that was formed by the upwelling of material below.
Geological activity under the “spongy” outer envelope of Venus may lead to the renewal of the surface of our neighboring planet, which keeps its surface active and vital. This is the result of a new study conducted by scientists with NASA using data from the three-decade-long Magellan mission.
Our planet has a hot core that heats the surrounding mantle, which in turn carries this heat energy to the lithosphere, the solid outer layer of the Earth, where it can be lost to space.
At the same time, convection of material within the mantle drives tectonic processes at Earth's surface, keeping the mixture of continental and oceanic plates moving.
By contrast, our neighbor Venus has no plate tectonics, so how it loses heat and what processes shape its surface have been long-standing questions for planetary scientists.
In the new study, NASA researchers investigated this mystery using data on semi-circular geological features on the surface of Venus known as "coronal topography" that were observed by the Magellan spacecraft in the early 1990s.
By taking new measurements of the "coronal topography" visible in Magellan's images, the team concluded that these features tend to appear where Venus's lithosphere is at its thinnest and most active.
"For a long time we were locked into this idea that Venus's lithosphere is stagnant and thick, but our view is now evolving," said paper author and geophysicist Dr. Susan Smirkar of NASA's Jet Propulsion Laboratory in California.
As the team showed, the thinner lithosphere provides less insulation, allowing more heat to escape from Venus' interior from floating plumes of molten rock within the planet's mantle.
The enhanced convection flow usually corresponds to increased volcanic activity underground, so the "crown" is likely to reveal the locations where geological processes are shaping the surface of Venus.
The scientists focused on 65 previously unstudied "crowns" identified a few hundred miles away.
They estimated the thickness of the lithosphere at the location of each "crown" by measuring the depth of trenches and ridges around this feature and applying a model of how the elastic lithosphere bends.
Based on this, they suggested that the lithosphere surrounding each "crown" was an average of seven miles thick, much thinner than previous studies had suggested.
Furthermore, it has been estimated that these regions of Venus' surface have a much greater heat flux than the Earth's average, indicating that the "crown" is geologically active.
"While Venus does not have Earth-style tectonics, these regions of the thin lithosphere seem to allow large amounts of heat to pass through, similar to regions where new tectonic plates form on the seafloor," Dr. Smrekar said.
Dr Samrekar added: "What's interesting is that Venus provides a window into the past to help us better understand how Earth came to be over 2.5 billion years ago."
The full results of the study have been published in the journal Nature Geoscience.
Source : websites