Venus Found to Have Earthlike Geology : Science: Scripps researcher reports that tectonic plates crash together--a phenomenon seen here.

Using recent data collected by the Magellan spacecraft, a Scripps Institution of Oceanography scientist says the geology of Venus may indeed be more like Earth than experts have believed, according to a report released today.

Until recently, scientists have been thwarted in their efforts to study Earth’s sister planet, which is similar to Earth in size, mass and distance from the sun.

But a window to the planet began to open when NASA sent up the Mariner 2 in 1962, the first spacecraft to visit the planet. The window was torn wide open, however, with the Magellan spacecraft, which has used cutting-edge radar imaging to penetrate Venus’ layer of clouds and unveil its surface.

The data from the Magellan spacecraft, fed back to scientists for almost two years, promises to change perceptions about the planet. With this information, some scientists now believe that a surface plate is sinking vertically into the planet’s interior. The process, called plate subduction, helps the planet cool as well as shapes its surface.

“What we are doing is figuring out one piece of the puzzle,” said David T. Sandwell, co-author of the report on Venus, published in today’s issue of the journal Science.

Here, the shape and structure of Earth’s surface has been molded by the sliding of enormous chunks called tectonic plates. In some areas of the globe, the plates collide, creating earthquakes and volcanoes.

The movement allows the planet to release heat, and the slow dance of the plates creates three different features on Earth. It can cause faults, where plates slide past one another, as with California’s San Andreas Fault. It can also cause spreading ridges, where new plates are created. And finally, the movement can cause the plates to crash together, with one going beneath the other.

Because of the similarities between Earth and Venus, experts have long tried to figure out whether Venus had the same sort of geology.

“People expected to see some type of tectonic plate activity on Venus that would allow the heat to get out,” said Sandwell, an associate professor of marine geophysics with UC San Diego’s Scripps Institution of Oceanography.

In fact, Sandwell and co-author Gerald Schubert, of UCLA’s department of earth and space sciences, found that the plates do crash together on Venus.

“It seems clear that the plate tectonics on Venus are different than on Earth, but this finding suggests there are some important features in common,” said David Grinspoon, an assistant professor of planetary science at the University of Colorado in Boulder.

The startling discovery rocks the foundation of what some scientists had believed.

When experts looked at data from Venus, based on the Pioneer radar map in 1980, “which wasn’t nearly as good as the Magellan map, we looked at that and asked, ‘Is there plate tectonics on Venus?’ ” Grinspoon said. “We said no. We couldn’t see any large, telltale land forms that are the signature of plate tectonics.”

But Sandwell and Schubert, with the benefit of the high-resolution Magellan data, were able to conduct a topographical analysis and detect the crucial land forms.

“What’s important about this is the potential for learning something about how planets evolve,” Grinspoon said. “What’s exciting about the study of Venus is that it is an incredibly earthlike planet in many respects. The Magellan mission has really laid the surface bare so we can make the first detailed comparisons between processes affecting Venus and Earth.”