Obscured by a hazy atmosphere 100 times thicker than Earth's, Venus is a notoriously difficult world to study. Ground temperatures on Venus exceed 450°C (842°F)—enough to melt lead and to have quickly degraded the Soviet robotic landers last placed there 40 years ago. Yet orbiting spacecraft have successfully mapped this planet with cloud-piercing radar, as well as identified constituent surface materials via narrow bands of infrared light that escape the Venusian atmosphere. Those investigations have revealed unmistakable volcanic structures and solidified lava flows, although there remains no definitive evidence as to whether volcanic eruptions still occur. Now, a new study suggests that such evidence is already in hand and points to Venus as the only other volcanically active planet in the solar system. See also: Atmosphere; Radar; Venus; Volcano
For this study, researchers exposed the mineral olivine in a laboratory to high temperature conditions such as those pervading Venus. Olivine forms underground, and after being spewed out on the surface by lava flows, the mineral chemically reacts with atmospheric gases to form different minerals, such as hematite and magnetite. The researchers wanted to gauge how fast olivine would transform in this way on Venus, as well as what the infrared signature of this change would look like. The scientists could then use this information to infer the age of lava flows on Venus that bear the infrared signature of olivine. See also: Infrared radiation; Magnetite; Mineral; Olivine
Under laboratory conditions, the olivine became coated by other minerals within weeks. The infrared signature of olivine also weakened over this short time period. This finding suggests that observations of olivine on Venus from orbit are indicative of very young lava flows. The researchers compared their data to observations previously gathered by the Venus Express orbiter, which confirmed that the orbiter had indeed identified olivine's signature. These results strongly suggest that lava continues to break out onto the surface of Venus, and thus, the planet remains geologically active. Although Venus Express stopped monitoring Venus in 2014, the hope is that future spacecraft equipped with appropriate sensors could follow up on this finding with supporting evidence that the volcanoes of Venus have not gone dormant. See also: Venus Express