NASA aircraft detects atomic oxygen in Venus’ dayside atmosphere

Atomic oxygen has been directly detected in Venus' dayside atmosphere.

In November 2021, NASA's retired Stratospheric Observatory for Infrared Astronomy (SOFIA) looked into the atmosphere of this hellish world. 

SOFIA, a Boeing 747SP outfitted with a 2.5-meter diameter telescope, provided essential data that revealed distinct signs of atomic oxygen present above the planet's perilous cloud cover.

The discovery of the atomic oxygen

A team of researchers, led by Professor Heinz-Wilhelm Hübers of the German Aerospace Center, examined the data collected from the array spectrometer aboard SOFIA.

As per Science Alert, SOFIA data was used to look for oxygen in the upper atmosphere at 17 different sites. Notably, atomic oxygen was detected at all these locations. 

The most abundant atomic oxygen was detected at 62 miles (100 kilometers) above the planet's surface.

According to their findings, the presence of oxygen on the dayside of Venus is a result of a complex chain of chemical reactions. When carbon dioxide and carbon monoxide molecules in Venus' atmosphere are exposed to sunlight, they decompose. This reaction causes these molecules to break down, releasing oxygen atoms. These oxygen atoms, in turn, contribute to the creation of atomic oxygen in the atmosphere.

The unique atmospheric circulation patterns on Venus play a crucial role in this process. They transport the newly formed atomic oxygen from the planet's dayside to its nightside. 

In the past, scientists had detected the existence of atomic oxygen in the night airglow of the Venusian atmosphere.

Atomic oxygen is distinct from the oxygen living organisms normally breathe, which is molecular oxygen (O2) — made up of two bound oxygen atoms. Atomic oxygen, on the other hand, is made up of single, unattached oxygen atoms and has a minimal lifespan due to its strong reactivity.

Findings important for planning future missions to Venus

Venus is often referred to as Earth's evil twin due to the remarkable similarity in size between the two planets. Earth boasts a radius of 3,959 miles (6,371 kilometers), while Venus measures 3,060 miles (6,052 kilometers). 

The insights gained from this new study could further assist scientists in unraveling the mystery of why the Venusian atmosphere turned out to be so different than Earth's. 

For quite some time, it has been theorized that Venus transformed into a nightmarish world as a consequence of an intense "runaway greenhouse effect."

It has been long assumed that Venus might have once had oceans. However, the planet’s close proximity to the Sun played a pivotal role in transforming its planetary conditions.

The intense solar radiation led to the evaporation of these oceans. The water vapor discharged into the atmosphere was then exposed to the Sun's extreme ultraviolet (UV) radiation. This UV light had a severe effect on the water molecules, causing them to disintegrate into their basic constituents (hydrogen and oxygen).

Carbon dioxide (CO2) began to collect in the atmosphere over time, forming a thick layer of this greenhouse gas.

This buildup of heat-trapping CO2 created a powerful greenhouse effect, causing severe surface temperatures and transforming Venus into the hot, inhospitable world that we know today.

These findings mark a significant advancement in the ongoing efforts to plan future missions to Venus, which are now gaining prominence with various space agencies and even startups

"Future observations, especially near the antisolar and subsolar points but also at all solar zenith angles, will provide a more detailed picture of this peculiar region and support future space missions to Venus," mentioned the study. 

The findings have been reported in the journal Nature Communications.

Study abstract:

Atomic oxygen is a key species in the mesosphere and thermosphere of Venus. It peaks in the transition region between the two dominant atmospheric circulation patterns, the retrograde super-rotating zonal flow below 70 km and the subsolar to antisolar flow above 120 km altitude. However, past and current detection methods are indirect and based on measurements of other molecules in combination with photochemical models. Here, we show direct detection of atomic oxygen on the dayside as well as on the nightside of Venus by measuring its ground-state transition at 4.74 THz (63.2 µm). The atomic oxygen is concentrated at altitudes around 100 km with a maximum column density on the dayside where it is generated by photolysis of carbon dioxide and carbon monoxide. This method enables detailed investigations of the Venusian atmosphere in the region between the two atmospheric circulation patterns in support of future space missions to Venus.

Originally published on Interesting Engineering : Original article

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