Astronomers shed light on the mystery of missing water on Venus

Astronomers shed light on the mystery of missing water on Venus
Astronomers shed light on the mystery of missing water on Venus

VenusVenus is the second closest planet to our Sun. We usually talk about it as a twin of the Earth. The two planets indeed have very similar sizes and masses. But, they are actually very different from each other. Among all the things that set them apart is the fact that there is almost no water on Venus. Scientists have been searching for an explanation for a long time. And today, finally, planetary scientists from the University of Colorado in Boulder (United States) seem to have found one. They detail it in the review Nature.

Let us first remember that on Venus, there is approximately 100,000 times less water than on our Earth. To help us get an idea of ​​the situation, the researchers point out that if all the water on Earth were spread over the entire surface of our Planet, the layer of liquid would reach approximately three kilometers deep. The same operation on Venus would lead to a water depth of only… three centimeters!

An ion responsible for the absence of water on Venus

How is it possible ? Even though scientists believe that billions of years ago, when they formed, Venus and Earth must have received the same amount of water. First, because at a given moment, cloudsclouds of carbon dioxidecarbon dioxide (CO2) in L’atmosphereatmosphere of Venus activated a powerful greenhouse effect. Temperatures rose to an average of 470°C and all the water evaporated, most of it drifting into space.

Venus could have housed an ocean before becoming the hellish planet we know

However, according to the astronomersastronomersVenus appears even drier than it should under these circumstances. “It’s like a bottle of water that you empty. There are always a few droplets left inside. But not on Venus », say the researchers. And the culprit could well be an ion with the chemical formula HCO+. The formylium cation, composed of a atomatom ofhydrogenhydrogena carbon atom and an atom ofoxygenoxygen.

Understand the mechanisms that maintain water on the planets

Planetary scientists explain that in the upper planetary atmospheres, water mixes with CO2 to form this particular ion. The idea is that in the atmosphere of Venus, it doesn’t survive long. When electronselectrons cross HCO ions+in fact, a recombinationrecombination takes place – chemists speak of dissociative recombination – and the ions are divided into two. Everything releases hydrogen (H) atoms which move away until they escape into space. And without hydrogen, it is impossible to reform water (H2O).

Venus would have been habitable until a great upheaval 715 million years ago

The problem is that according to calculations by researchers at the University of Colorado, Venus should host significant volumesvolumes of HCO+. It should even be the most abundant ion in its atmosphere. But never before have scientists observed this ion around the one we call theEvening StarEvening Star ». “Because we haven’t yet pointed the right instruments at Venus”, assure planetologists. Even the mission of NASANASA DaVinci (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) will not be able to detect HCO+ in the atmosphere of Venus. But now that scientists know what to look for, the next missions to our second planet Solar systemSolar system could include a dedicated instrument. Because it must be remembered, water is essential to life. And understand the conditions that support the presence of liquid water in theUniverseUniverseis therefore crucial to our search for extraterrestrial life forms.

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