The best evidence for active volcanism on Earth’s neighbouring planet, Venus, has been acquired by the European Space Agency (ESA)’s Venus Express spacecraft.
Being almost the same size as Earth and possessing a composition that’s also similar, it’s long been thought that the second planet from the Sun has an internal heat source, which has possibly come about due to radioactive heating. Seeing as this heat has to escape somehow, it’s thought that it may be belched out by volcanic eruptions on Venus’ surface.
Whether the mountainous peaks on the planet’s surface – discovered by radar observations made by previous spacecraft – are still volcanically active today has been a hot topic in planetary science for a long time. Now it seems that Venus Express is pointing towards a volcanically energetic world, according to the results that the mission has yielded in its eight-year study of the planet, which ended last year.
Using the near-infrared channel of the spacecraft’s monitoring camera to map out Venus’ thermal emission, localised changes in the surface brightness, evident in images taken a few days apart, were spotted by an international team of planetary scientists led by Eugene Shalygin from the Max Planck Institute for the Solar System Research in Germany.
The region that has caught their attention is the Ganiki Chasma rift zone, an area already considered to be one of the most recently geologically active locations on the planet. Ganiki Chasma is likely have formed from the fracturing of the terrain that’s often associated with the upwelling of hot magma below the crust. This molten material later spills out onto the surface to create a lava field. The Ganiki Chasma rift zone lies close to the volcanoes Ozza Mons and Maat Mons.
“We have now seen several events where a spot on the surface suddenly gets much hotter and then cools down again,” says Shalygin. “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.”
Venus has an extremely thick atmosphere that’s capable of blocking out a spacecraft’s view of its surface. Nevertheless, Shalygin and his team are impressed with Venus Express’ efforts in obtaining the new set of results, which have revealed a particularly interesting hotspot. The area known simply as ‘Object A’ swelters at an impressive temperature of 830 degrees Celsius (1526 degrees Fahrenheit), much higher than the global average of 480 degrees Celsius (896 degrees Fahrenheit).
“It looks like we can finally include Venus in the small club of volcanically active Solar System bodies,” says Håkan Svedhem, ESA’s Venus Express project scientist. “Our study shows that Venus, our nearest neighbour, is still active and changing in the present day – it is an important step in our quest to understand the different evolutionary histories of Earth and Venus.”