Why is there almost no water on Venus? New research offers an explanation

Using computer simulations, scientists discovered that hydrogen atoms can escape Venus’ atmosphere through a process called dissociative recombination. As a result, Venus is losing – day after day – about twice as much water as previous estimates indicated.

Venus is really dry. If you spread all the water on Earth across its surface, our planet would be underwater for about two miles. However, if you did the same thing on Venus, the water would not rise more than three centimeters. But Venus wasn’t always so dry.

Scientists suspect that Venus absorbed an amount of water equivalent to what Earth absorbed during its formation billions of years ago. But at a certain point things went wrong. Clouds of carbon dioxide in Venus’ atmosphere caused a powerful greenhouse effect, eventually raising the temperature on the planet’s surface to 500 degrees Celsius. In the process, all of Venus’ water evaporated into vapor and most of it disappeared into space. However, this evaporation cannot explain why Venus dried out and continued to lose water.

Searching for an explanation, a research team led by Michael Chaffin and Erin Kanji used computer models to understand Venus as a vast chemical laboratory. They zoomed in on the various interactions that occur in the planet’s atmosphere. According to researchers, HCO+ (a Molecular ion The presence of one hydrogen atom, one carbon atom, and one oxygen atom) in Venus’ atmosphere may be the reason for the water escaping.

Later task

HCO+ is constantly produced in Venus’ atmosphere, but individual ions do not survive for long. When they collide with electrons in the atmosphere, they split, causing hydrogen atoms to escape into space. In this way, Venus is deprived of one of the two elements of water (the other is oxygen).

The research team calculated that Venus could only become so dry if the planet had more HCO+ in its atmosphere than expected. The bad thing is that scientists have never observed HCO+ around Venus. According to Chavin and Kanji, this is because the right tools for this are never available.

Although several space probes have traveled to Venus, none of them have equipment on board that can detect HCO+, even though HCO+ should actually be one of the most abundant ions in Venus’ atmosphere. Even NASA’s next DAVINCI mission, scheduled to launch at the end of this decade, will not be able to detect HCO+. So we have to wait for a later mission.