Of all the planets in the solar system, Venus has the most volcanoes. Much of the planet is covered by volcanic deposits less than 300 million years old, and volcanic activity played a key role in its history. While the precise timeline of Venus’ volcanic past is still under debate and some data suggest the planet may still have active volcanoes, the evidence remains inconclusive.
So far, researchers have had difficulty determining whether there are active volcanoes on Venus for several reasons. The planet’s atmosphere is corrosive and has high pressures and temperatures—over 450°C (842°F)—that make it inhospitable to the types of spacecraft that can last years on Mars or the Moon. Meanwhile, thick clouds of acid sulfur dioxide limits visible observation of the planet’s surface, so researchers have turned to other remote measurements, including radar collected by NASA’s Magellan spacecraft, to map it.
According D’Incecco et al. , a new methodology could finally help solve the mysteries of volcanic activity on Venus. As applied in a recent study, this approach combines geological mapping of cooled lava flows from previous eruptions with additional radar data from the Magellan mission. Specifically, it relies on measurements of the planet’s radar emissivity – a measure of how its surface interacts and emits microwave radiation.
Different parts of the surface of Venus have different emissivity levels that correspond to different rock properties, providing clues to their composition. In particular, recent research suggests that radar emissivity can be used to determine the degree of chemical weathering experienced by lava flows after they erupt and come into contact with the hostile atmosphere. This wear occurs over weeks or months, so emissivity can potentially help identify recent lava flows.
The authors combined radar emissivity measurements with geological mapping to compare three Venusian volcanoes: Maat Mons, Ozza Mons, and Sapas Mons. The findings suggest that some lava flows at Maat Mons may be relatively young.
Looking ahead, the same approach could be applied to additional data from Magellan to further explore Venus’ volcanism. The methodology may also be important for future Venus missions that will provide high-resolution radar emissivity measurements, including the European Space Agency’s EnVision mission and NASA’s Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy (VERITAS) mission.
Coupled with information from additional future missions, including NASA’s DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gas, Chemistry and Imaging) mission and the Venera-D mission, the new strategy may finally help reveal which, if any, Venus’ volcanoes are still active, as well as providing new insights into the planet’s volcanic past.