An overlooked molecule could solve the Venus water mystery
- May 21, 2024
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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An overlooked molecule could solve the Venus water mystery
Sub: Science and tech
Sec: Space sector
Context:
- A recent study published in Nature examines why water disappeared from Venus.
About the study:
- More than four billion years ago, Venus had enough water to cover its surface with an ocean 3 km deep. Today, the planet only has enough for this ocean to be 3 cm deep.
What are the reasons for loss of water?
Hellish Atmosphere:
- The first is its hellish atmosphere which is a result of its carbon dioxide-rich composition, which causes a strong greenhouse effect.
- The planet’s surface is hotter than water’s boiling point, simmering at 450 degrees C. So water can only exist as vapor in Venus’ atmosphere.
Planet’s proximity to the Sun:
- The Sun’s heat and ultraviolet radiation combined to shred water molecules into their constituent hydrogen and oxygen atoms in Venus’s ionosphere — the upper region of the atmosphere, where charged atoms, molecules, and their electrons zoom around at high speeds.
- The two theories broadly blame thermal and non-thermal processes for the water loss.
- The thermal process refers to hydrodynamic escape. As the Sun heated Venus’s outer atmosphere, it expanded, allowing hydrogen gas to leak to space.
- This escape lasted until the outer atmosphere sufficiently cooled, by about 2.5 billion years ago.
HCO+ dissociative recombination reaction (DR):
- Scientists have known for a while that HCO+ molecules drive hydrogen escape on Mars.
- On Venus, the HCO+ dissociative recombination reaction (DR) occurs in bulk at an altitude of about 125 km, above the clouds made of sulphuric acid.
- HCO+ is created when a carbon monoxide molecule (CO) loses an electron while absorbing an hydrogen atom.
- DR is the reverse reaction: HCO+ absorbs an electron and breaks up into CO and a hydrogen atom. These energetic hydrogen atoms then escape into space.
- It was found that the reaction accelerated water decline once the hydrodynamic escape of hydrogen gas ended.
- HCO+ DR could have doubled the rate at which Venus lost water by hydrogen escape.
- The model predicted that the amount of water on Venus would have stayed roughly the same from nearly 2 billion years ago.
- As a non-thermal process, the HCO+ DR reaction would’ve gone on indefinitely and drained all the water.
- The thermal process was time-bound because the upper atmosphere returned to thermal equilibrium.
About Venus:
- Venus is the second planet from the Sun, and the sixth largest planet.
- It’s the hottest planet in our solar system.
- Venus is a cloud-swaddled planet named for a love goddess, and often called Earth’s twin.
What are various missions to Venus?
BepiColombo:
- BepiColombo is a joint mission of the European Space Agency and the Japan Aerospace Exploration Agency to the planet Mercury.
- The mission comprises two satellites launched together: the Mercury Planetary Orbiter and Mio.
- Scientists found a signature of carbon ions escaping Venus in data collected by the BepiColombo spacecraft.
NASA’s MAVEN:
- MAVEN is a NASA spacecraft orbiting Mars to study the loss of that planet’s atmospheric gasses to space, providing insight into the history of the planet’s climate and water.