In general, we struggle to understand what other worlds may be shaking, rattling, and erupting. Jupiter’s moon Io clearly has active volcanoes. Enceladus has geysers. We’ve seen these features doing their thing, but other worlds are more secretive in their geologic activity. Venus, for instance, may have active volcanoes, but if it does, they are hidden beneath a thick layer of clouds that makes direct imaging all but impossible.

Where direct imaging is impossible, radar can reflect back the necessary data to understand what is going on. Back in the 1990s, the Magellan spacecraft mapped most of Venus, and now Pierro D’Incecco and his collaborators have used not just the shape profiles recorded in these maps but also the reflectivity of the surface to try and understand how different volcanic flows are layered on one another and how they have aged. 

Different kinds of minerals absorb and reflect radar light in different ways and this quality is called radar emissivity. This information – the emissivity –  is recorded along with the shape of the surface being radar mapped. D’Incecco and his team’s work indicates that over time, the emissivity of lava rock changes as it is exposed to the caustic weather of Venus. 

In a new paper appearing in JGR Planets, they look at lava flows on Sapas and Ozza Montes and find that these flows have emissivities consistent with them being well-weathered by time, and they suggest that further study of other regions may be able to reveal ongoing volcanism. The catch is that we don’t know if we have all the data we need from Magellan. If we don’t, there is the hope of getting new and better data in the future when ESA’s EnVision mission and NASA’s VERITAS mission get to Venus in the future.

More Information

Is Venus Volcanically Active? New Approach Could Provide an Answer (Eos)

“The Geologically Supervised Spectral Investigation as a Key Methodology for Identifying Volcanically Active Areas on Venus,” P. D’Incecco et al., 2021 July 12, JGR Planets