24 Feb. () –
Archival data from NASA supports that Venus may be losing heat due to geological activity in regions called coronas, possibly as early tectonic activity on Earth.
Earth and Venus are rocky planets of similar size and chemical composition, so they should lose their internal heat to space at about the same rate. It is well known how the Earth loses heat, but the mechanism of heat flow from Venus has been a mystery.
A study using data from three decades ago from NASA’s Magellan mission has taken a new look at how Venus cools and found that thin regions of the planet’s upper layer may provide an answer.
Our planet has a hot core that heats the surrounding mantle, which transports that heat to Earth’s rigid outer rocky layer, or lithosphere. The heat is then lost to space, cooling the upper region of the mantle. This mantle convection drives tectonic processes at the surface, keeping a mosaic of moving plates in motion. Venus lacks plate tectonics, so planetary science has long wondered how it loses heat and what processes shape its surface.
The study addresses this mystery from the observations that the Magellan spacecraft made in the early 1990s of almost circular geological features of Venus called coronae. By making new measurements of the corona visible in the Magellan images, the researchers concluded that coronae tend to be situated where the planet’s lithosphere is thinnest and most active.
“For a long time we have clung to the idea that the Venusian lithosphere is stagnant and thick, but our view is evolving,” he says. it’s a statement Suzanne Smrekar, a research scientist at NASA’s Jet Propulsion Laboratory, who led the study published in Nature Geoscience.
Just as a thin sheet releases more body heat than a thick duvet, a thin lithosphere allows more heat to escape from the planet’s interior through floating plumes of molten rock that rise to the outer layer. Normally, when heat flux increases, subsurface volcanic activity increases. So that, the coronae probably reveal places where active geology is shaping the surface of Venus today.
The researchers focused on 65 previously unstudied coronas, up to a few hundred kilometers in diameter. To calculate the thickness of the surrounding lithosphere, they measured the depth of the trenches and ridges surrounding each crown. They found that the ridges are closer together in areas where the lithosphere is more flexible or elastic. Using a computer model of how an elastic lithosphere bends, they determined that, on average, the lithosphere around each coronal is about 11 kilometers thick, much less than previous studies suggest. These regions have an estimated heat flux higher than the Earth average, suggesting that the coronas are geologically active..
“Although Venus does not have similar tectonics to Earth’s, these regions of thin lithosphere appear to be letting off significant amounts of heatsimilar to areas where new tectonic plates are forming on the Earth’s seafloor,” says Smrekar.
