Active lava flows on Venus raise the stakes for future exploration

The Sif Mons area with the active volcanic region highlighted in red

IRSPS – Università d’Annunzio: [email protected]​t

Recent lava flows spotted on Venus suggest the planet could be much more geologically active than first thought, possibly as active as Earth.

The geological processes producing these flows, first spotted in the 1990s by the Magellan spacecraft, are likely to still be active and will be important areas to observe in upcoming missions to Venus.

Venus was once thought to be a “dead” planet, with possible geological activity long having ceased. But recent reanalysis of Magellan data has found compelling evidence that the activity is ongoing, such as a volcanic vent that changed shape over a period of eight months. However, it has been unclear how widespread this activity might be, with little direct evidence.

Davide Sulcanese at D’Annunzio University in Chieti, Italy, and his colleagues have now reanalysed Magellan radar data, looking at two different areas on Venus’s surface: the northern volcano Sif Mons and a plain in the east known as Niobe Planitia.

They found variations in brightness from the reflected radar signal over time, which suggests there are areas of material that have expanded, most likely from moving lava flows.

To confirm this explanation, Sulcanese and his team had to rule out others, such as atmospheric interference or the spacecraft accidentally changing its intended observation angle, as Magellan only captured the same area once every eight months.

Once the researchers had confirmed the flows’ volcanic nature, they then worked out their properties, such as how quickly lava was being produced. The team’s lower estimates, of 3.78 and 5.67 cubic kilometres per year for Sif Mons and Niobe Planitia, respectively, are roughly the same as the average volcano on Earth.

Sulcanese and his team also used these figures to estimate the total volcanic activity on Venus. “According to this estimate, Venus could be far more volcanically active than expected,” says Sulcanese, being the same order of magnitude as Earth’s total rate of volcanic activity.

These areas will be important to look at for planned missions to Venus, such as NASA’s VERITAS and the European Space Agency’s EnVision, which are both aiming to launch in the early 2030s. “It’s probable that [these areas] will still be active in the early 2030s,” says Sulcanese. “Geologically speaking, 30 years is like a few seconds for the activity of volcanic fissions.”

“This paper does strengthen the case for current volcanic activity,” says Philippa Mason at Imperial College London, who is also a member of the EnVision team. Known sites of geological activity, like the ones identified by Sulcanese and his team, could be imaged at least three times during EnVision’s observation cycle, she says, which will give us a much more detailed look at Venus’s interior and surface geological processes than Magellan.

“We still don’t know today how these processes work,” says Sulcanese. “Do we have some kind of one tectonic plate planet, or some sort of microplates, or something not like the plates we have on Earth? By studying this volcanic activity, we can better understand.”

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