Hidden beneath a thick atmosphere, volcanoes may still be erupting on the surface of Venus, a new study finds.
The findings, described in the journal Geophysical Review Letters, reveal that our nearest planetary neighbor could be far more active than previously thought.
Venus, our closest planetary companion, could provide insights of its own, but it's shrouded in thick clouds of sulfuric acid that block out visible light. And that's too bad, said study coauthor James Head, a planetary geoscientist at Brown University, because in many ways it would be the best planet to study to learn more about Earth and its history.
"Venus – in terms of its size, its density, position in the solar system (which is important in its formative years) – is literally the most Earth-like planet," Head said. "And I think that if we could see what was going on in the formative years of Earth, that would be really incredible."
Russian landers in the 1970s and '80s revealed features that looked somewhat familiar: plateaus, features that looked like mountain belts, but surprisingly few craters on the surface. The terrain indicated that the surface had been active, undergoing the kind of geophysical churn seen on Earth.
Venus, like Mars, had clearly had volcanic activity in the distant past – but could it have some today?
"People were thinking, 'Well, is it like the Earth, which is very active, or is it like the moon and Mars, which are like a bunch of craters?'" Head said.
Data from NASA's Magellan spacecraft, which entered Venusian orbit in 1990, seemed to say that Venus was geophysically dead. But if it had been inactive for a very long time, then it should be heavily cratered, which is clearly not the case.
To get at that question, the scientists turned to the European Space Agency's Venus Express spacecraft, using data from its Venus Monitoring Camera to look for bright spots that signaled local lava flows. They focused on the planet's rift zones, with the idea that any hot spots of geologic activity would be there.
Sure enough, the scientists found bright spots that indicate temperature spikes caused by flowing lava, a sign that Venus is still active. These spots don't cover the planet, but pop up only along the rift lines crossing the planet's surface.
The rift zones with these hot spots are somewhat reminiscent of the East African rift zone on Earth, Head said. While the dynamics on Venus are clearly very different than the ones on Earth today, Venus' current activity could hint at what Earth looked like before its tectonic plates were formed.
"That's why Venus is so important.... Maybe this is what the Earth looks like before plate tectonics got started," Head said. "Maybe we're looking at the beginning of plate tectonics on Venus."