A Breakthrough Discovery: Oxygen Atoms Unveiled in Venus’ Dayside Atmosphere

For the first time, oxygen atoms have been identified in the dayside atmosphere of Venus, free from being part of larger molecules. This revelation not only marks a significant advancement in our understanding of Venus but also paves the way for future missions to the enigmatic planet.

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For the first time in history, the presence of oxygen atoms in Venus’ dayside atmosphere, independently existing without being bonded to larger molecules, has been confirmed. 

Previous observations had detected oxygen on Venus’ night side, but this latest study has unveiled a far more widespread distribution than ever before.

These findings represent a crucial step forward for the future exploration of Venus, now gaining increased attention from space agencies worldwide.

Oxygen’s Expected Presence

The abundance of oxygen in Venus’ atmosphere is not disputed. As the third most common element in the universe, its presence on Venus was expected even before the first spacecraft ventured near the planet.

 These early missions revealed an atmosphere saturated with carbon dioxide and carbon monoxide (CO₂ and CO), clearly indicating the role of oxygen in chemical reactions.

However, in planetary atmospheres, oxygen tends to form compounds by binding with other elements in the crust or atmosphere due to its highly reactive nature. Therefore, the existence of free atomic oxygen is by no means guaranteed. 

Yet, prior observations by the Venus Express satellite had already unveiled hints of atomic oxygen radiating on the planet’s night side. The most recent research not only confirms the prevalence of atomic oxygen but also provides valuable insights into the mechanisms responsible for its creation and distribution.

A Pioneering Study

Professor Heinz-Wilhelm Hübers and his colleagues from the German Aerospace Center employed the Stratospheric Observatory for Infrared Astronomy (SOFIA) to conduct a thorough examination of Venus’ upper atmosphere at 17 different locations. Astonishingly, they found atomic oxygen present in every location.

This free oxygen is produced through the action of sunlight on carbon dioxide (CO₂) and carbon monoxide (CO) molecules. Venus’ formidable winds transport these oxygen atoms to the night side, where they combine to form molecular oxygen (O₂), similar to the oxygen found in Earth’s atmosphere. 

These oxygen molecules then interact with other elements, contributing to the complex chemistry of Venus’ atmosphere. Despite this redistribution, the densities of atomic oxygen on the dayside exceed those on the night side by up to fivefold.

A Vital Role in Venus’ Atmosphere

The research team emphasizes that atomic oxygen plays a significant role in Venus’ atmospheric processes. When an oxygen atom collides with a carbon dioxide molecule, it imparts energy to the molecule, which is subsequently emitted as radiation at a wavelength of 15 micrometers. 

This radiative cooling mechanism is dominant in the upper layers of Venus’ atmosphere and is crucial in preventing the planet from becoming even hotter. Venus is already the hottest planet in the Solar System, and without this cooling process, its temperatures would be even more extreme.

The Concentration of Atomic Oxygen

Atomic oxygen is most concentrated at approximately 100 kilometers (60 miles) in Venus’ atmosphere. On Earth, this altitude is considered the boundary between the upper atmosphere and outer space due to the thinning of the atmosphere. However, Venus has a much denser atmosphere that extends much higher.

The highest concentrations of atomic oxygen are located between the two dominant atmospheric circulation patterns on Venus. One of these patterns occurs below 70 kilometers (43.5 miles), while the other is situated above 120 kilometers (74.6 miles). 

The peculiar rotation of Venus, where its day is longer than its year, results in high-altitude winds that move faster than the planet’s rotation. These unique atmospheric dynamics contribute to the distribution of atomic oxygen within the Venusian atmosphere.

Read the original article on Nature Communications.

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