Chapter 1: Venus's Atmospheric Secrets

The Venusian Hemispherical Globes illustrate the northern and southern hemispheres of Venus, captured through over ten years of radar surveys, culminating in the NASA Magellan mission from 1990 to 1994.

Recent studies have unveiled a groundbreaking discovery: highly reactive oxygen atoms have been identified in both the daylight and nighttime regions of Venus's atmosphere. This revelation suggests that Venus may have once boasted a more hospitable atmosphere, possibly even containing liquid water on its surface. However, the planet has undergone significant transformations, primarily due to the runaway greenhouse effect that has turned it into the harsh environment we recognize today. Currently, Venus is enveloped in a thick, noxious atmosphere predominantly composed of carbon dioxide, with sulfuric acid clouds creating a hostile sauna-like environment. The surface temperatures can reach an astonishing 450 degrees Celsius (842 degrees Fahrenheit), coupled with crushing atmospheric pressure.

Visualize Venus as the rebellious sibling of Earth. Although it shares similarities in size and composition, that’s where the parallels end. One may wonder why Venus garners less attention than Mars. The answer lies in its extreme conditions, which pose significant challenges for exploration. In contrast, Mars has a more accommodating atmosphere and the intriguing possibility of harboring life. However, recent hints regarding the presence of the organic compound phosphine in Venus's clouds have sparked renewed interest in studying this enigmatic planet.

In a separate study enhancing our understanding of Venus's atmospheric evolution, astronomers have confirmed the direct detection of atomic oxygen on both the daylight and nighttime sides. Unlike the molecular oxygen (O2) we breathe, which consists of bonded oxygen atoms, atomic oxygen comprises single, free-floating oxygen atoms, making it highly reactive.

The latest observations were made using NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), a modified Boeing 747 equipped with an 8.9-foot infrared telescope. A team of German astrophysicists analyzed data from SOFIA, focusing on 17 atmospheric locations on Venus during both day and night. Their results confirmed the presence of molecular oxygen, a gas formed from non-bonded oxygen atoms, across all examined regions.

“Furthermore, measuring the altitude distribution of atomic oxygen in Venus's atmosphere is crucial for improving our understanding of its chemistry and physics, especially in comparison to Earth,” said Heinz-Wilhelm Hübers, the lead researcher of the study.

While oxygen has previously been detected on the nightside of Venus, this marks the first time it has been observed in sunlit areas. Scientists propose that molecular oxygen accumulates as sunlight breaks down carbon dioxide and carbon monoxide molecules, which are then transported to the nighttime side by high-altitude winds, where they react with other elements.

Nevertheless, this does not imply that astronauts could simply breathe on Venus as they do on Earth. The molecular oxygen present on Venus differs significantly from breathable oxygen on our planet. While Earth's breathable oxygen consists of two bonded atoms (O2), the oxygen on Venus exists as individual, reactive atoms. Attempting to inhale it would lead to severe reactions with lung tissues, preventing oxygen from entering the bloodstream.