Venus鈥� beauty treatment? (Image: NASA/Sygma/Corbis)
Venus is leaking lava. Researchers have found oozing volcanoes on our closest planetary neighbour, a discovery that may help solve the planet鈥檚 deepest geological riddles.
Past observations revealed that Venus鈥� surface is 鈥渘ew鈥�, at least in geological terms. Because it doesn鈥檛 sport many craters, scientists think the planet has been paved over by upwelling lava within the last billion years. There have been hints of more recent volcanism, too: some terrain looks as young as a few hundred thousand years and we have seen changes in the amount of sulphur 鈥� an element produced by volcanoes 鈥� in the planet鈥檚 atmosphere. But no solid evidence of fresh lava.
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Until now. An international team has dug through data from the European Space Agency鈥檚 Venus Express probe, which orbited from 2006 until 2014, and found short-lived hot patches they attribute to lava lakes bubbling up along a geological rift.
鈥淏y chance we found this bright event, and by carefully analysing the region we found three more,鈥� says of the Max Planck Institute for Solar System Research in Gottingen, Germany.
Frequent flows
The thick Venusian atmosphere makes it tough to see what鈥檚 going on at the surface. The team used thermal imaging at wavelengths that can penetrate through the clouds, and then looked only at the clearest images they could get. Even those images were smeared out so that features smaller than 50 kilometres remained blurry.
They found blobs that grew hotter over a few days and then quickly cooled 鈥� as might be expected for lava flows quenched under the pressure of the atmosphere.
鈥淭his is such beautiful evidence for volcanism,鈥� says at Arizona State University. Venus, like Earth, has heat from its formation and from radioactive elements trapped inside, and must have had some way to release this. So the discovery isn鈥檛 a total shock, she says.
Although lava wasn鈥檛 unexpected, it wasn鈥檛 clear whether Venus spewed it in frequent trickles or catastrophic, global floods. The team鈥檚 findings suggest that some flows are little and often.
There鈥檚 also the question of whether Venus was ever habitable. Active volcanoes mean the planet has a 鈥渢iny little carbon cycle鈥�, Elkins-Tanton says, which churns between its atmosphere and its insides. We think the exchange of carbon is important for helping planets maintain a balanced climate. While Venus鈥檚 cycle clearly wasn鈥檛 enough to make it habitable, the fact that it鈥檚 there at all may imply that exoplanets like it, with just one tectonic plate, might be able to keep stable atmospheres.
Knowing the composition of the lava would help, Elkins-Tanton says. 鈥淲e鈥檙e a little way away from a Venus mission that would go sample the surface,鈥� she says. 鈥淏ut this gives us some good motivation.鈥�
Journal reference: , DOI: 10.1002/2015GL064088
