Researchers may have discovered a missing ingredient in the chemical composition of Venus’s clouds that could explain their color and UV “mottling,” solving a long-standing mystery. What are the clouds of Venus made of? Scientists know that they consist mainly of drops of sulfuric acid with some water, chlorine and iron. In the thick and hostile atmosphere of Venus, their concentrations vary with altitude. But so far they have not been able to identify the missing component that could explain the cloud spots and lines that are only visible in the UV range.

Groundbreaking discovery in Venus research

In a published study Science DevelopmentsResearchers from the University of Cambridge have synthesized iron-containing sulphate minerals that are stable under the harsh chemical conditions in Venus’ clouds. Spectroscopic analysis has shown that the combination of two minerals, rhomboclase and acid iron sulfate, may explain the mysterious feature of UV absorption on our neighboring planet.

Search for answers

“The only available data on cloud composition was collected by probes, revealing strange properties of clouds that we cannot yet fully explain,” said Paul Rimmer of the Cavendish Laboratory and a co-author of the study. “Specifically, when examined in ultraviolet light, Venus clouds showed a special ultraviolet absorption pattern. What elements, compounds, or minerals are responsible for this observation?”

Formulated based on the chemistry of Venus’ atmosphere, the team synthesized a variety of iron-containing sulfate minerals at the Department of Earth Sciences’ Aqueous Geochemistry Laboratory. By suspending the synthesized materials in various concentrations of sulfuric acid and observing the chemical and mineralogical changes, the team narrowed the list of candidate minerals to rhomboclase and acid iron sulfate, whose spectroscopic properties were examined under specially designed light sources to mimic the spectrum. solar flares (Rimmer’s FlareLab; Cavendish Laboratory).

Researchers at Harvard University measured the ultraviolet absorption patterns of ferric iron in extremely acidic conditions in an attempt to simulate even more extreme Venus clouds. The scientists are part of the newly formed Origins Federation, which supports such collaborative projects.

“The patterns and level of absorption shown by the combination of these two mineral phases are consistent with the dark UV spots seen in Venusian clouds,” said co-author Clancy Zhijian Jiang from Cambridge’s Department of Earth Sciences. “Experiments aimed at this goal have revealed a complex chemical network in the atmosphere and shed light on the cycling of elements on the surface of Venus.”

Future exploration of Venus

“Venus is our closest neighbor, but it still remains a mystery,” Rimmer said. “We will have the chance to learn more about this planet in the coming years, thanks to future NASA and ESA missions that will study its atmosphere, clouds and surface. This research paves the way for future studies.”