Oxygen Detected Directly in Venus’ Dayside Atmosphere : ScienceAlert

It is legal. Astronomers observing the atmosphere of Venus have directly detected clear signs of atomic oxygen during the day, hanging above the planet’s toxic clouds.

Atomic oxygen is known to exist in the planet’s atmosphere, according to theoretical models, and has been directly detected in the night sky of Venus; but the discovery during the day means that we have new insight into the dynamics of the Venusian atmosphere, and the circulation patterns there, said the team led by physicist Heinz-Wilhelm Hübers of the German Aerospace Center (DLR).

Venus is a planet that scientists are eager to learn more about. It is similar to Earth in many ways; but completely, completely different from others. Its hardness and composition are similar to Earth’s, but where Earth is green, lush, wet, and crawling with life, Venus is a pit of death. It is covered by dense, condensing clouds made up mostly of carbon dioxide, creating a greenhouse that results in an average temperature of around 464 degrees Celsius (867 Fahrenheit).

Those clouds drop acid rain on Venus, and the entire atmosphere orbits the planet at high speeds. Winds far below Venus’s cloud tops can gust about 700 kilometers (more than 400 miles) per hour. On Earth, the highest wind speed ever recorded was a hurricane of 407 kilometers (253 miles) per hour.

We don’t know if Venus and Earth ended up being very different from each other, but learning about our neighbor can help us figure that out. Did Venus ever get on the same path as Earth, and turn into the wrong place? Or was it the evil twin from the beginning?

Understanding the atmosphere of Venus can help us understand the difference between it and Earth. And one of the ways to do that is to follow oxygen.

Atomic oxygen is not the same as the oxygen you breathe. The last is molecular oxygen, or O2, which consists of two oxygen atoms bonded together. Atomic oxygen consists of single, isolated oxygen atoms, and it does not tend to stay for long, because it is very reactive and easily binds to other atoms. Here on Earth, it is abundant at high altitudes, where it is created by the photodissociation of molecular oxygen. Basically, solar photons split atmospheric O2.

A similar process is thought to have occurred on Venus. Venus’ atmosphere is primarily carbon dioxide; when light from the Sun hits this CO2, photodissociation splits molecules into atomic oxygen and carbon monoxide. Carbon monoxide is also subject to photodissociation.

When these atoms orbit Venus’ night sky, they recombine into carbon dioxide, a process that makes the planet’s night sky glow. Atomic oxygen has been observed as part of this process, but it had never been seen before in daylight.

Map of surfaces, temperature, and atomic oxygen density on Venus. (Hübers et al., Nat. Commun., 2023)

Hübers and his team studied data collected by the Stratospheric Observatory for Infrared Astronomy (SOFIA) flying high in the Earth’s atmosphere, in the terahertz wavelength range that crosses the microwave and far-infrared. On three separate occasions, the spacecraft flew by, collecting data on 17 locations on Venus: seven during the day, nine at night and one at the airport.

In all 17 locations, the team found atomic oxygen, reaching a height of 100 kilometers (62 miles). This corresponds to a height that sits directly between the two dominant patterns of atmospheric circulation on Venus: a strong circumpolar flow less than 70 km that rotates opposite the planet’s rotation, and a subsolar-to-antisolar flow in the atmosphere above 120. kilometers.

This means, the researchers say, that atomic oxygen represents a previously untapped resource for investigating this area of ​​atmospheric evolution on Venus.

“Future observations, especially near the antisolar and subsolar regions but also at all solar zenith angles, will provide a more detailed picture of this unusual region and support future space missions to Venus,” the researchers wrote.

“Along with measurements of atomic oxygen in the atmospheres of Earth and Mars, these data can help improve our understanding of how and why the Venus and Earth atmospheres are so different.”

The study was published in Natural Communication.