Astronomers have found direct evidence of atomic oxygen floating above the toxic clouds of our “evil” neighboring planet.
In our solar system we find two strikingly similar planets: Earth and Venus. They are likely the same age, have similar sizes, and most likely consist of the same building blocks. However, these celestial bodies show significant differences. For example, Earth has clear blue skies and an oxygen-rich atmosphere. Meanwhile, Venus is surrounded by a dense cloud of carbon dioxide, nitrogen and various trace gases. But oxygen can also be found in the turbulent atmosphere of our “evil” twin sister, researchers have now shown.
Just to be clear: we’re talking about a different form of oxygen than that found on Earth. In the case of Venus, it is atomic oxygen. “Atomic oxygen consists of only one oxygen atom,” explains researcher Heinz-Wilhelm Hubers in a conversation with Scientias.nl Outside. “So this is different from molecular oxygen, which is made up of two oxygen atoms and which we need to breathe.”
The researchers detected this atomic oxygen using the terahertz spectrometer on board SOFIA (see box). After analyzing the data collected, they discovered clear signs of the presence of atomic oxygen on both sides of the planet day and night.
More about Sofia
SOFIA is an abbreviation for the Stratospheric Observatory for Infrared Astronomy. It is an observatory on board a modified Boeing 747SP aircraft used for astronomical observations in the infrared range. SOFIA rises into the stratosphere, where it rises above much of the water vapor in Earth’s atmosphere, giving it a clearer view of the universe.
The discovery is special. “Until now, atomic oxygen has not been observed on the dayside of Venus,” Hubers says. But according to models, it must exist and be generated under the influence of solar radiation. Our measurements confirm this prediction. Moreover, the results showed that the concentration of atomic oxygen decreases as solar radiation decreases. Dayside winds transport atomic oxygen to the nightside, where it then accumulates locally.
This means that atomic oxygen can be found on both sides of Venus day and night. This has now been measured directly for the first time. Although we know that atomic oxygen plays a crucial role in the photochemistry and energy balance of Venus’ atmosphere, it has never before been observed directly on the dayside of Venus. Previous night-side observations have been limited to studying Venus’ faint skyglow, a subtle emission of light through the planet’s atmosphere.
How does it arise?
How does atomic oxygen on Venus see daylight? This type of oxygen is produced on the day side of Venus by the decomposition of carbon dioxide (CO2) and carbon monoxide (CO) and is then transported to the night side. “Atomic oxygen is formed by photolysis,” Hubers explains when asked. “Solar radiation breaks down carbon dioxide molecules, and oxygen is released from these carbon dioxide molecules as atomic oxygen (this also happens to a much lesser extent with carbon dioxide).” The team examined 17 points on either side of the planet, and found that oxygen was detected at all locations, with its highest concentrations about 100 kilometers above the surface.
It is not surprising that it accumulates here. There are two strong air movements in the atmosphere of Venus: below an altitude of 70 km, hurricane-force winds blow opposite to the direction of Venus’ rotation, while above an altitude of 120 km, strong winds blow following the direction of its rotation. Between these conflicting air currents there is a layer of atomic oxygen. The temperature of atomic oxygen ranges from about -120°C on the day side to -160°C on the night side. Its concentration is about ten times lower than in the Earth’s atmosphere.
The discovery of atomic oxygen in the turbulent atmosphere of Venus is a major step forward. “Our measurements contribute to a deeper understanding of the photochemistry of the atmosphere of Venus,” Hubers explains. “In addition, they have shown that atomic oxygen can serve as a tracer of wind movements at an altitude of about 100 km. Existing models can also be confirmed and improved thanks to our measurements.”
At the same time, the study also expands our knowledge about our still-mysterious neighboring planet. “For example, we now better understand how much atomic oxygen is produced on the dayside of Venus and how that relates to radiation from the Sun shining on Venus,” Hubers says. So, we’re slowly starting to learn more about Venus, which is still less studied than our closest neighbor Mars.
Ultimately, researchers hope to learn how Venus and Earth, despite their strong similarities, took different and very different paths today. While we don’t know exactly how Venus and Earth took such divergent paths, research into our neighboring planet may provide us with insight. Was Venus on the same path as Earth and made a wrong turn somewhere? Or is he the evil twin of our planet from the beginning?
More about Venus
Venus shows similarities to Earth in many ways. Although the planet has almost the same size, structure, mass and density, as mentioned, the similarities end there. Venus is experiencing greatly enhanced greenhouse effect, as its thick atmosphere traps all the heat and its surface temperatures rise to 465 degrees Celsius. Furthermore, the planet is surrounded by a cloud cover filled with corrosive sulfuric acid. However, experts believe this was not always the case. Many scientists suspect that Venus was originally Earth-like and may have contained water. If this is true, the big question is what caused the planet to take such a different path at one time and become so far apart from Earth today.
Understanding Venus’ atmosphere can help us understand its contrasts with Earth. One way to achieve this is to follow oxygen pathways. “The levels of atomic oxygen in Earth’s atmosphere are very different from those on Venus,” Hubers says. “This is because on Earth, atomic oxygen is produced by the decomposition of molecular oxygen, which is essential for life. Research in the field of atomic oxygen can therefore contribute to a deeper understanding of the history of both atmospheres.”
In addition, hopes are also pinned on several upcoming space missions to Venus. In recent years, a few space probes have headed to Venus. But fortunately that will change soon. Not only will NASA be back, but the US agency will send at least two space probes to our closest neighbors, but the European Space Agency will also invite our “sister” for a visit. They promise to be exciting and interesting missions that will ultimately create a global picture of our sister planet and characterize it from top to bottom. In doing so, we will likely learn more about the still-mysterious planet Venus.
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