ESA's Venus Express spacecraft has found the best evidence yet of active lava flows on Venus. Earlier missions to Venus have shown that the surface bears the unmistakable scarring of fierce, ancient volcanic activity. However, prior to Venus express, no mission had been successful in directly imaging clues to contemporary volcanism. This quirk has baffled scientists for years, as it has long been assumed that Venus hosts an internal heat source, and that heat has to escape somehow.
Venus is often given the moniker "Earth's twin", owing to the fact that it possesses a similar mass and composition to our planet. In reality, the landscape of Venus is scarred and barren, cloaked in a thick, toxic atmosphere that has created a runaway greenhouse effect resulting in a surface temperature of 462° C (864° F).
Previous observations of Venus' atmosphere have obliquely hinted at the presence of active volcanism. For example, a spike in sulphur dioxide levels in Venus' upper atmosphere between 2006 and 2007 seemed to suggest a fierce but brief bout of volcanic activity, the after effects of which gradually subsided over the following five years.
One of the key impediments to our understanding of Venus is the dense nature of its atmosphere, which makes direct observation of the surface all but impossible. ESA's Venus Express was able to pierce the atmosphere and probe the surface of Earth's hellish twin by imaging in the infrared spectrum using its Venus Monitoring Camera (VMC).
Data returned from the VMC recorded a number of incidents in which the surface temporarily brightened and subsided over the period of just a few days along the Ganiki Chasma rift. The region sits close to the volcanoes Ozza Mons and Maat Mons, indicating that the events may have been volcanic in nature.
"We have now seen several events where a spot on the surface suddenly gets much hotter, and then cools down again," states Eugene Shalygin of the Max Planck Institute for Solar System Research, Germany, and lead author of the paper on the findings. "These four ‘hotspots’ are located in what are known from radar imagery to be tectonic rift zones, but this is the first time we have detected that they are hot and changing in temperature from day to day. It is the most tantalising evidence yet for active volcanism."
A paper regarding the findings is available in the journal Geophysical Research Letters.