Oxygen is detected in the atmosphere of Venus – 11/10/2023 – Science

Oxygen makes up about 21% of Earth’s air, with the rest of our atmosphere mainly made up of nitrogen. And most living beings — including people, as we know well — need oxygen to survive.

Earth’s neighboring planet, Venus, offers a quite different story. Its thick, noxious atmosphere is dominated by carbon dioxide —96.5%— with smaller amounts of nitrogen and trace gases. Oxygen is practically absent. In fact, because Venus receives much less scientific attention than other planets such as Mars, direct detection of its oxygen has been difficult.

Using an instrument aboard the Sofia air observatory — a Boeing 747SP aircraft modified to carry an infrared telescope in a joint project between NASA and the German Aerospace Center — scientists have now detected atomic oxygen in a thin layer between two other layers of the Venusian atmosphere. .

They noted that this atomic oxygen, which consists of a single oxygen atom, differs from molecular oxygen, which has two oxygen atoms and is breathable.

Researchers directly detected oxygen for the first time on the Sun-facing side of Venus — where it is actually produced in the atmosphere — and also detected it on the side facing away from the Sun, where it had previously been spotted by a ground-based telescope in Hawaii. . Venus rotates much more slowly than Earth.

“The atmosphere of Venus is very dense. The composition is also very different from Earth,” said German Aerospace Center physicist Heinz-Wilhelm Hübers, lead author of the study published in the journal Nature Communications.

The thick atmosphere on the second planet from the Sun traps heat in a runaway greenhouse effect.

“Venus is not hospitable, at least to the organisms we know from Earth,” Hübers added.

Oxygen is produced on the dayside of the planet by ultraviolet radiation from the Sun, which breaks down atmospheric carbon dioxide and carbon monoxide into oxygen atoms and other chemicals, researchers said. Some of the oxygen is then transported by winds to the night side of Venus.

“This detection of atomic oxygen on Venus is direct proof of the action of photochemistry — triggered by solar UV radiation — and the transport of its products by the winds of Venus’ atmosphere,” said astrophysicist and co-author of the study, Helmut Wiesemeyer, from the Institute Max Planck of Radio Astronomy, in Germany.

“On Earth, our life-protecting stratospheric ozone layer represents a well-known example of this photochemistry,” Wiesemeyer added.

On Venus, there is a layer of clouds containing sulfuric acid at a height of about 40 miles (65 km) above the planetary surface, with hurricane-force winds blowing in the opposite direction to the planet’s rotation. About 75 miles (120 km) above the surface, strong winds blow in the same direction as the planet’s rotation.

Oxygen was found concentrated between these two fierce layers, at an altitude of about 60 miles (100 km). Oxygen temperatures ranged from about minus 184 degrees Fahrenheit (minus 120°C) on the day side of the planet to minus 256 degrees Fahrenheit (-160°C) on the night side.

Previously used methods to detect Venusian oxygen on the dayside were indirect, based on measurements of other molecules in combination with photochemical models.

Venus, with a diameter of about 7,500 miles (12,000 km), is slightly smaller than Earth. In our solar system, Earth resides comfortably in the “habitable zone” around the sun — the distance considered neither too close nor too far from a star to support life, with Venus near the inner edge and Mars near the outer edge.

“We are still at the beginning of understanding the evolution of Venus and why it is so different from Earth,” Hübers said.