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, chiefly 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 2 500 000 years - and likely much less, possibly even currently active. "This is a significant result," says Håkan Svedhem, ESA Venus Express Project Scientist.
Whilst the gradual resurfacing scenario might not be the most spectacular, it does make Venus look a little more Earth-like.
"There are some intriguing models of how Venus could have completely covered itself in kilometres 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 Dr Smrekar.
This is the volcanic peak, Idunn Mons, (at 46°S, 214.5°E) in Imdr Regio. The background image is radar data from NASA's Magellan mission. Bright areas are either rough or have an eastward facing slope, or both. Dark areas are smooth. The radar data is draped on the Magellan topography, shown with a vertical exageration of 30 times. The summit stands about 2.5 km above the plains and has a diameter of ~200 km. The colored overlay shows the emissivity derived from ESA's VIRTIS surface brightness data, taken from Venus Express. The high emissivity area (shown in red and yellow) is centered on the summit and the bright flows that originate there.
(Photo Credit: 2010 California Institute of Technology; NASA/JPL)
This figure shows the volcanic peak Idunn Mons (at 46°S, 214.5°E) in the Imdr Regio area of Venus. The topography derives from data obtained by NASA's Magellan spacecraft, with a vertical exaggeration of 30 times. Radar data (in brown) from Magellan has been draped on top of the topographic data. Bright areas are rough or have steep slopes. Dark areas are smooth.
The colored overlay shows the heat patterns derived from surface brightness data collected by the visible and infrared thermal imaging spectrometer (VIRTIS) aboard ESA's Venus Express spacecraft. Temperature variations due to topography 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 km above the plains, and on the bright flows that originate there. Idunn Mons has a diameter of about 200 km.
The VIRTIS data was collected from May 2006 to the end of 2007.
(Photo Credit: ESA/NASA/JPL)
Source: European Space Agency