Scientists have identified a mechanism for water loss Venus this could explain how the once water-rich world became completely dry.
In the newly discovered process involving a previously overlooked molecule high in Venus’ atmosphere, water escaped from Venus at twice the rate previously estimated. Because the faster loss of water means it takes less time for the planet’s water reservoir to evaporate, scientists say Venus may have had oceans — and potentially habitable conditions — for longer than previously thought. before the drying process begins.
“This will provide more time for possible life to arise,” co-author of the study Erin Kangyresearch scientist at the Laboratory for Atmospheric and Space Physics (LASP) in Colorado, writes in The conversation. “However, our results do not mean that the oceans or life were definitely present – answering that question will require much more science over many years.”
Previous studies have shown that both Venus and The Earth probably received similar amounts of water early in their history, mostly from steam-spewing volcanoes and icy comets that often bombarded the worlds. Assessments I guess Venus once had enough moisture to cover its surface in about 1.8 miles (3 kilometers) of water. However, Venus receives far more sunlight than Earth, and previous research has revealed that this sunlight likely vaporized the planet’s water reservoir by breaking atmospheric water molecules into hydrogen and oxygen atoms. Once freed, the light hydrogen escapes into space through a process known as hydrodynamic escapementleaving Venus without one of the two ingredients needed to form water.
The process explains how most of Venus’ water evaporated from its atmosphere, probably during the first billion years of the planet’s history. But that doesn’t account for the last 330 feet (100 meters) of water that was likely left behind after the escape process stopped soon after most of the hydrogen atoms left Venus, the researchers of the new study said.
“As an analogy, say I threw away the water in my water bottle. There will still be a few droplets left,” the study’s lead author Michael Chaffinresearcher at LASP, said in a statement. The remaining water could not have escaped Venus in the same way, but it must have been removed from the atmosphere relatively quickly to account for the hot, dry world we know today.
In the new study, the researchers suggest that the residual water is removed by a new mechanism known as HCO+ dissociative recombination (nicknamed DR). In this process, positively charged hydrogen, carbon and oxygen atoms combine with negatively charged electrons to produce carbon monoxide (CO) and hydrogen as a byproduct, after which the hydrogen escapes into space. Since water is the original source of Venus’ hydrogen reservoir, this process “effectively dries out the planet,” the researchers said. Computer models of reactions in Venus’ upper atmosphere show that this mechanism closes the gap between expected and observed water loss, according to the study, published Monday (May 6) in the journal Nature.
“One of the surprising conclusions from this work is that HCO+ should in fact be among the most abundant ions in the Venusian atmosphere,” Chaffin said in the statement.
However, scientists have never observed this molecule on Venus. Previous missions to the planet are not designed to detect it, but measure individual reactants that produce HCO+ in the atmosphere.
None of the three upcoming missions to Venus are designed to detect the molecule either. NASA’s VERITAS and Europe’s Envision mission, both scheduled to launch in 2031, lack the necessary scientific instruments to study the loss of hydrogen from the upper atmosphere of Venus, where the DR process takes place. NASA’s DAVINCI probe, also scheduled to launch in 2031, will collect measurements of the atmosphere’s pressure, temperature and winds, but only below 43 miles (70 kilometers).
Therefore, confirming the presence of HCO+ and determining this phase of Venus’ history will have to wait a long time.
