Atomic oxygen is produced during daytime on Venus by photosynthesis of carbon dioxide and carbon monoxide.
Atomic oxygen is a major species in the mesosphere and thermosphere of Venus. It peaks in the transition region between the two dominant atmospheric circulation systems, the retrograde super-rotational flow below 70 km and the antisolar flow above 120 km. However, past and current detection methods are indirect and based on measurements of other molecules in combination with photochemical models. Hubers and many others. Direct detection of atomic oxygen both day and night by measuring its ground-state shift at 4.74 THz. Image credit: Mattias Malmer / NASA.
Venus is known to rotate so slowly that one day on Venus is equivalent to 243 Earth days.
Atomic oxygen, a major species in the mesosphere and thermosphere of Venus, is produced during the planet’s daytime by the breakdown of carbon dioxide and carbon monoxide and then transported at night.
Atomic oxygen is important for the photochemistry and energy balance of the Venusian atmosphere, but it has not yet been directly observed during the Venusian daytime.
Nighttime detections have previously been limited to observations of the Venusian nightglow, dimming of light emitted by the planetary atmosphere.
In a new study, Dr. Heinz-Wilhelm Hübers, a researcher at the Deutsches Zentrum für Luft-und Raumfahrt and Humboldt-Universität zu Berlin, and his colleagues used Germany to study a total of 17 points on the day and night sides of Venus. NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) Astronomical Receiver at Terahertz Frequencies (UPGRADE) in-flight Array Spectrometer.
„Observations were carried out in the early evenings of November 10, 11 and 13, 2021,” they said.
„In total, 17 phases have been measured on Venus: seven during the day, nine at night and one on Terminator.”
The researchers detected atomic oxygen at all observed points and found that it was concentrated at an altitude of about 100 km.
The measurements were based on the atomic oxygen ground state microstructure at 4.74 terahertz.
They found variations in column densities, with maximum densities recorded during daytime.
„The mean temperature of the Venus continuum brightness is 246 K, which is 65-70 km above the cloud layer,” they reported.
„The temperature of atomic oxygen is approximately 156 K during the day and approximately 115 K at night, corresponding to an altitude of 100 km.”
„Future observations, particularly near the antisolar and subsolar points but at all solar zenith angles, will provide a more detailed picture of this strange region and support future space missions to Venus such as NASA’s DAVINCI mission or ESA’s ENVISION mission,” they added.
„Along with measurements of atomic oxygen in the atmospheres of Earth and Mars, these data may help improve our understanding of how and why the atmospheres of Venus and Earth differ.”
The Findings Published in the magazine Natural communication.
_____
HW. Hubers and many others. 2023. Direct detection of atomic oxygen during the day and night of Venus. Not Common 14, 6812; doi: 10.1038/s41467-023-42389-x