2023-11-10 11:27:44
This will also interest you
[EN VIDÉO] Venus, the burning planet with a deadly atmosphere Meet our neighbor Venus. Nicknamed the Shepherd’s Star, the planet has always fascinated…
The second planet in our Solar System in distance from the Sun, Venus is the subject of numerous studies: despite notable similarities with the Earth, particularly in terms of their size and composition, the two planets have had very distinct histories.
When the Earth evolved into an environment conducive to the development of life, with mild temperatures and a relatively stable climate, VenusVenus, sometimes referred to as “Earth’s twin sister”, transformed itself into a very inhospitable planet. , with surface temperatures around 462°C and an atmosphere dominated by carbon dioxidecarbon dioxide so dense that the ground pressure there is 92 times greater than on Earth. Scientists are thus seeking to better understand the complex atmosphere of Venus in order to explain the mechanisms that led it to evolve so differently from Earth.
A hellish world difficult to fathom
Due to its relatively short distance from Earth, Venus was the first planet to be visited by a space probe (NASA’s Mariner 2 probe flew by Venus in 1962), and the first planet on which a lander landed. successfully landed (the Soviet Union’s Venera 7 probe touched down on Venus in 1970). However, its surface and atmosphere remain very difficult to study.
In its thick atmosphere dominated by carbon dioxide – which gives it a greenhouse effect so powerful that its surface temperature is on average higher than on the planet Mercury, closer to the Sun – sit thick cloudsclouds of sulfuric acidsulfuric acid, at altitudes between 45 and 70 kilometers. These clouds are very reflective, meaning they reflect most of the sunlight they receive back into space. The Venusian atmosphere is thus so opaque that it is impossible to see its surface in visible light (by comparison, the Earth’s surface is easily observable from space in the absence of clouds).
Very little information was thus collected on the planet before the invention of technologies allowing its observation in other domains of the electromagnetic spectrum — typically the radar, infraredinfrared and ultravioletultraviolet domains — making it possible to pierce through its thick clouds. And if the arrival of these technologies marked a real leap forward for the exploration of this sulphurous planet, scientists are still making new discoveries today, gradually adding new blocks of information helping to improve our understanding of it. understanding.
Fruit of the development of these new techniques, the Stratospheric Observatory for Infrared Astronomy (Sofia, acronym for Stratospheric Observatory for Infrared AstronomyStratospheric Observatory for Infrared Astronomy), resulting from a collaboration between the American and German space agencies, observes space in the infrared domain from a Boeing operating in the stratosphereterrestrial stratosphere, at a sufficiently high altitude so that its observations are not hampered by the atmosphere of our Planet. Thanks to the data collected by Sofia, a team of scientists announced that they had for the first time detected atomic oxygen (O) in the “day” side (lit by the Sun) of Venus. They publish their results in the journal Nature Communication.
Atomic oxygen, a marker of atmospheric dynamics
Although it is also present on Earth, atomic oxygen differs from the oxygen we breathe: we inhale dioxygen molecules (composed of two oxygen atoms), while what we call atomic oxygen corresponds to a single oxygen atom. It is a highly reactive compound that is constantly seeking to bind to other molecules. Although its presence in the Venusian atmosphere has long been suggested thanks to various atmospheric models, atomic oxygen had until now only been observed on the “night” side of the planet. The detection of atomic oxygen in the side illuminated by the Sun sheds new light on the atmospheric dynamics of Venus.
“The detection of atomic oxygen in the side illuminated by the Sun sheds new light on the atmospheric dynamics of Venus”
On Earth, atomic oxygen is relatively abundant at high altitudes of the atmosphere, where it is formed by the action of solar radiationsolar radiation on atmospheric molecules: photonsphotons coming from the Sun can “break” the molecules they meet, creating two new compounds. This phenomenon is called photodissociation. On Earth, atomic oxygen is thus formed by photodissociation of dioxygen.
According to the researchers, a similar process seems to operate in the atmosphere of Venus: under the action of solar radiation, the carbon dioxide molecules (composed of one carbon atom and two oxygen atoms) in its atmosphere are dissociated to create oxygen atoms and carbon monoxide moleculescarbon monoxide (made up of one carbon atom and one oxygen atom). Atomic oxygen thus seems to form in the illuminated side of Venus (where it has just been detected for the first time), before recombining with other molecules in the nocturnal nocturnal side.
But what intrigues the authors most are the altitudes at which atomic oxygen has been detected. According to their results, at all the points where atomic oxygen was observed (seven on the day side, nine on the night side and one at the terminator terminator which separates the illuminated and unilluminated sides of the planet), the concentration was maximum at an altitude of around 100 kilometers. It is right between two major Venusian atmospheric currents: the powerful super-rotating current, at an altitude less than 70 kilometers where powerful winds blow in the opposite direction of the planet’s rotation, and the subsolar-antisolar flow, at an altitude greater than 120 kilometers, where the wind blows from the sunny side towards the night side.
Venusian atomic oxygen thus represents a hitherto unexploited source of information for understanding the transition between these two major atmospheric currents. Researchers hope that future observations will provide more detailed data on the Venusian atmosphere, especially since understanding its dynamics is crucial for the smooth running of future missions to our neighbor.
1699616255
#Atomic #oxygen #detected #time #day #side #Venus
