Venus has similar geological activity to Earth’s

The colored overlay in the left image shows the heat patterns derived from surface brightness data collected by the visible and infrared thermal imaging spectrometer (VIRTIS) aboard Venus Express. Temperature variations due to topography (which has been exaggerated in the image) were removed. The brightness signals the composition of the minerals that have been changed due to lava flow. Red-orange is the warmest area and purple is the coolest. The warmest area is situated on the summit, which stands about 2.5 kilometers above the plains, and on the bright flows that originate there. Idunn Mons has a diameter of about 200 kilometers. Not unexpectedIt has long been recognized that there are simply not enough craters on Venus and that some process, probably volcanic, is wiping the planet’s surface clean. The biggest question is whether the process happens quickly or slowly.The results from Venus Express suggest slowly, with smaller, more frequent eruptions.In 2008, Jörn Helbert and Nils Müller, Institute of Planetary Research, German Aerospace Center, Berlin—both of whom are co-authors on this new work—published a map of the variation of infrared emissivity across the southern hemisphere of Venus.JPL scientist Sue Smrekar and her colleagues then targeted three regions that geologically resemble Hawaii, well known for its active volcanism. The two groups could show that the regions on Venus have higher emissivities than their surroundings, indicating different rock compositions.On Earth, lava flows react rapidly with oxygen and other elements in the atmosphere, changing their composition. On Venus, the process should be similar, though more intense because of the hotter, denser atmosphere, which is chiefly made of carbon dioxide.The researchers interpret the fact that the lava flows appear to have different compositions from their surroundings as being evidence of a lack of surface weathering, indicating that the flows erupted relatively recently.They estimate that the flows are possibly as geologically recent as 2500000 years—and likely much less, possibly even currently active. “This is a significant result,” says ESA Venus Express project scientist HÃ¥kan Svedhem."There are some intriguing models of how Venus could have completely covered itself in kilometers of volcanic lava in a short time, but they require that the interior of Venus behaves very differently from Earth. If volcanism is more gradual, this implies that the interior may behave more like Earth, though without plate tectonics ,” says Smrekar.Paul Guinnessy