Why the discovery of an active volcano on Venus is important Story-level



VEnus had a lot going for him. About the same diameter and density as Earth, it orbits in the habitable zone of the solar system, just the right distance from the sun for liquid water to exist. But the planet’s biological prospects were destroyed long ago by a runaway greenhouse effect that left it with an atmosphere that is 95% carbon dioxide and 90 times Earth’s pressure, the equivalent of being a mile deep in the ocean. ocean. Venus’ surface temperatures hover around 475ºC (900ºF), or hot enough to melt lead.

But there is one fiery feature of Earth that Venus has long been thought to lack: volcanoes. Without the tectonic plates that drive eruptions on Earth, Venus is said to be a volcanically inactive place, having seen its last explosion perhaps a billion years ago. Or so it seemed. Now, however, a new paper in Science reveals modern volcanic activity on Venus, a discovery that may make scientists rethink how rocky planets like Earth form and even help us search for habitable worlds surrounding other stars.

The new findings are based on a fresh look at images captured of Venus by NASA. Magellan spacecraftwhich orbited the planet taking radar soundings of its surface between 1990 and 1994. Overall, Magellan mapped more than 40% of the face of Venus, capturing images that at the time, they were stored on DVD, and shipped to various astronomy laboratories in cardboard boxes. Magellan images are now available to researchers online. Robert Herrick, a planetary scientist at the University of Alaska, Fairbanks, and Scott Hensley, a senior research scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, seized on that fact to take a second look at images from 30 years ago.

The area that caught their attention is a region known as Alta Regio, near Venus’s equator, which is home to the planet’s two largest dormant volcanoes: Ozza Mons and Maat Mons. What the researchers were looking for was any sign that it might still there may be residual volcanic activity associated with the giant vents. The mere lack of plate tectonics wouldn’t necessarily rule it out: Venus is still rich in subsurface radioactive material that could provide the heat needed to produce an eruption.

Hensley and Herrick examined images taken eight months apart, between February 1991 and October 1991, and after about 200 hours of study, they hit the mark. A small circular vent associated with Maat Mons that, in the February image, measured 2.2 square meters. km (1 square mile), had doubled in size and was kidney-shaped in the October image. “The vent is almost full to the brim in the [second] image,” the researchers wrote in their paper. “We speculate that a lava lake formed during the 8-month interval between images.”

But “speculate” was a key word. During the two passes Magellan made over the Alta Regio region, he took his radar scans of the target vent from different angles. So it was always possible that the apparent change in the size and shape of the vent was just the result of a change in perspective. So the researchers ran hundreds of computer simulations of the twin images, trying to determine if it was possible to reproduce the change they had seen through simple changes in viewing angle. But the tests were empty.

“The simulation cannot reproduce the kidney shape of the vent,” Hensley and Herrick wrote. “We definitely concluded that ventilation has changed.”

Where there is one volcano, there should be more, perhaps many more. The researchers studied just 1.5% of the surface of Venus in their 200 hours of image comparison and plan to dive back into images from three decades ago to learn more. “While this is just one data point for an entire planet,” Hensley said in a statement released by NASA, “it confirms that there is modern geological activity. [on Venus].”

That has implications that go beyond just one planet in our own familiar solar system. More than 5,000 exoplanets they have been seen only in our galaxy and the really big discoveries are small, rocky worlds with a solid surface where life could take hold. Venus, Earth, and Mars check that box, and they all orbit in the habitable zone. But only Earth caught all the lucky breaks to become the garden world that it is. The better we understand how those planets form, the better we’ll know where else to look for life.

“There have been a lot of general scenarios put forward to explain why Earth and Venus are so different now,” Herrick wrote in an email to TIME, “including some that have Venus as habitable with something like plate tectonics for three years.” quarters of their history. In terms of general ideas, the evolution of Venus and Mars over time will shape our ideas about what controls where the habitable zone is around other stars in other solar systems.”

“Solve questions like [the evolution of Venus]”, Hensley added in an email to TIME, “will provide clues about the evolution of rocky planets in general and which ones may or may not be habitable”.

The search for life in the cosmos continues. The new finds from so close to home advance that effort at least one small step.

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