Is Venus -Thought to Be Dead- Geologically Active?

6a00d8341bf7f753ef01347fbda633970c "The geological history of Venus has long been a mystery," said Sue Smrekar, a scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Previous spacecraft gave us hints of volcanic activity, but we didn't know how long ago that occurred. Now we have strong evidence right at the surface for recent eruptions."

New observations reveal that volcanoes on Venus appeared to erupt between a few hundred years to 2.5 million years ago, which suggests the planet may still be geologically active, making Venus one of the few worlds in our solar system that has been volcanically active within the last 3 million years.

The evidence comes from the European Space Agency's Venus Express mission, which has been in orbit around the planet since April 2006. The science results were laid over topographic data from
NASA's Magellan spacecraft. Magellan radar-mapped 98 percent of the surface and collected high-
resolution gravity data while orbiting Venus from 1990 to 1994.

Scientists see compositional differences compared to the surrounding landscape in three volcanic
regions. Relatively young lava flows have been identified by the way they emit infrared radiation.
These observations suggest Venus is still capable of volcanic eruptions. The findings appear in the
April 8 edition of the journal Science.

The volcanic provinces, or hotspots, on which Smrekar and her team focused are geologically similar
to Hawaii. Scientists previously detected plumes of hot rising material deep under Venus' surface.
Those plumes are thought to have produced significant volcanic eruptions. Other data from the planet
suggest that volatile gases commonly spewed from volcanoes were breaking down in its atmosphere.

The rate of volcanism will help scientists determine how the interior of the planet works and how
gases emitted during eruptions affect climate.

Something is smoothing Venus' surface, because the planet has only about 1,000 craters, a relatively
small amount compared to other bodies in our solar system. Scientists think it may be the result of
volcanic activity and want to know if it happens quickly or slowly. The Venus Express results suggest
a gradual sequence of smaller volcanic eruptions as opposed to a cataclysmic volcanic episode that
resurfaces the entire planet with lava.

Smrekar and her team also discovered that several volcanic features in the regions they studied showevidence of minerals found in recent lava flows. These mineral processes correspond to the youngestvolcanic flows in each region, giving scientists additional support for the idea they formed duringrecent volcanic activity. On Earth, lava flows react rapidly with oxygen and other elements in theatmosphere when they erupt to the surface. On Venus, the process is similar, although it is more ntense and changes the outer layer more substantially.

Scientists call Venus Earth's sister planet because of similarities in size, mass, density and volume.Scientists deduce that both planets shared a common origin, forming at the same time about 4.5billion years ago. Venus also is the planet on which the runaway greenhouse effect was discovered.The planet is cloaked in a much less friendly atmosphere than that found on Earth. It is composedchiefly of carbon dioxide, which generates a surface temperature hot enough to melt lead, and asurface pressure 90 times greater than that on Earth.

The small group of worlds in our solar system known to be volcanically active today includes Earth
and Jupiter's moon Io. Crater counts on Mars also have suggested recent lava flows. Scientists are
studying evidence of another kind of active volcanism that involves ice-spewing volcanoes on other
moons in our solar system.

NASA sponsored Smrekar's research. The European Space Agency built and manages Venus Express. JPL is managed for NASA by the California Institute of Technology in Pasadena.

Casey Kazan via NASA/JPL


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