Venus may have been a temperate planet harboring liquid water for 2-3 billion years, while a dramatic transformation that began more than 700 million years ago floated about 80% of the planet. The study, presented today at the Michael Wayne Institute for Space Sciences Godard Joint EPSC-DPS 201
40 years ago, NASA's Pioneer Venus mission found harrowing hints that the planet's "twisted sister" to Earth may have once had water on a shallow ocean. To see if Venus may have ever had a stable climate capable of holding liquid water, Dr. Wei and his colleague Anthony Del Genio have created a series of five simulations suggesting different levels of water coverage.
In all five scenarios, they found that Venus was able to maintain stable temperatures between a maximum of about 50 degrees Celsius and a minimum of about 20 degrees Celsius for about three billion years. Today, Venus may even maintain a temperate climate if there were no series of events that caused the release or "burst" of carbon dioxide stored on the planet's rocks about 700-750 million years ago.
"Our hypothesis is that Venus may have had a stable climate for billions of years. It is possible that closely the global resurrection event may be responsible for transforming it from the Earth-like climate to the hellish hot house we see today. "said Way.
Three of the five scenarios examined by Way and Del Genio accepted the topography of Venus as we see it today and considered the deep ocean an average of 310 meters, a shallow layer of water averaging 10 meters and a small amount of water locked in the soil. For comparison, they also included a scenario with Earth's topography and a 310-meter ocean and finally a world completely covered by an 158-meter-deep ocean.
To simulate environmental conditions 4.2 billion years ago, 715 million years ago today researchers have adapted a 3-D model of general circulation to account for the increase in solar radiation as our Sun warms throughout life as well as changing atmospheric compositions.
Although many researchers believe that Venus is beyond the inner boundary of the habitable zone of the solar system and is too close to the sun to hold liquid water, a new study suggests that this may not be the case.
"At the moment, Venus has almost twice the solar radiation that we have on Earth. However, in all the scenarios we have modeled, we have found that Venus can still maintain surface temperatures subject to liquid water, "said Way.
At 4.2 billion years, shortly after its formation, Venus would to end the period of rapid cooling, and its atmosphere would be dominated by carbon dioxide, if the planet evolved in a similar manner to Earth over the next 3 billion years, carbon dioxide would be pulled out of silicate rocks and confined to the surface. an era modeled before 715 million years ago, the atmosphere would probably be dominated by nitrogen with traces of carbon dioxide and methane – similar to today on Earth – and these conditions could remain stable to this day
The cause of the nausea that led to the dramatic transformation of Venus, is a mystery, though probably related to the volcanic activity of the planet.One possibility is large amounts of magma blowing out, releasing carbon dioxide from molten rocks in the atmosphere. The magma hardens before it reaches the surface and this creates a barrier which means that the gas cannot be reabsorbed. The presence of large amounts of carbon dioxide caused the escape of the greenhouse effect, which led to the burning 462 degrees average temperatures found today on Venus.
"Something happened on Venus where a huge amount of gas released into the atmosphere and couldn't be swallowed up again by the rocks. There are some examples of large-scale extinguishing on Earth, such as the creation of the Siberian traps 500 million years ago, which is associated with mass extinction, but nothing on this scale. transformed Venus, "said the Road.
There are still two major unknowns that need to be addressed before the question of whether Venus was habitable can be fully answered. The first relates to how quickly Venus cools initially and whether it is able to condense liquid water to its surface. The second is unknown whether the global resurgence event was a single event or just the latest in a series of events that go back billions of years to Venus history.
"We need more Ece missions to Venus investigate and understand more fully its history and evolution, "said Way." However, our models show that there is a real opportunity Venus have been habitable and radically different from Venus, which we see today. This opens all kinds of consequences for exoplanets found in the "Venus zone", which may actually host liquid water and a temperate climate. "
New research sheds light on the possibility of Venus's past life
The Europlanetary Society
Is Venus habitable? (2019, September 22)
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