The moons of Mars were once habitable

NASA: Venus was habitable until disaster millions of years ago

  • Nasa researchers suspect that life could have been possible on Venus millions of years ago.
  • Their models suggest that the planet once had a mild climate, with liquid water and even oceans.
  • This could still be the case today, but a still puzzling catastrophe occurred that radically changed the fate of Venus and turned it into a hothouse hell.
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Given that Venus bears the name of the Roman goddess of love and beauty, it is an extremely uncomfortable planet from a human point of view. The surface of Venus has the hottest average temperature of all planets in the entire solar system, it is covered with volcanoes and the atmosphere consists mainly of carbon dioxide - a heat hell that one would rather not visit. However, this has not always been the case.

Data from Venus probes and model simulations have been suggesting for a number of years that Venus might once have had a life-friendly and even Earth-like climate. But a catastrophe about 700 million years ago abruptly ended this state of affairs. Today there are extreme temperatures averaging more than 450 degrees Celsius on Venus and it has a very dense, cloudy atmosphere. So far it was unclear whether our neighboring planet could only have been a twin of the earth in the climate, or whether there was also liquid water on the prehistoric Venus - a basic requirement for the creation and maintenance of life.

Life on Venus could have been possible for three billion years

To check whether the climate on Venus millions of years ago was mild enough for liquid water, Michael Way of the Goddard Institute for Space Studies at NASA and his colleagues simulated various scenarios in a model.

To do this, the researchers assumed four variants of the planet's surface: a Venus with today's surface but deep oceans in its depressions, a Venus with shallow water surfaces, a Venus with a surface similar to that of the earth and a Venus completely covered with water. The NASA scientists exposed their model planets to the incidence of radiation as it existed or still exists 4.2 billion years ago, 715 million years ago and today at the height of Venus' orbit. They also simulated different atmospheres.

It turned out that Venus could have been a livable planet with a mild climate for up to three billion years. In all the scenarios tested by the researchers, the temperature on our neighboring planet was between 20 and 50 degrees Celsius - although it is closer to the sun than the earth.

Catastrophic greenhouse effect could have turned Venus into a glowing hell

"Venus currently receives twice as much solar radiation as the earth," says Way in a statement on the study that was recently presented at a meeting of the European Planetary Science Congress. “But in spite of this, we found in all scenarios that the temperatures could still be suitable for liquid water today.” Although the planet is just within the habitable zone of the solar system, theoretically it would still have been a climatic twin of the earth today can.

But it is not. Around 700 million years ago, the fate of Venus suddenly changed. In a comparatively short time, an enormous amount of CO2 and water vapor was released, which triggered a massive greenhouse effect. As a result, Venus heated up extremely strongly and became the hostile planet it is today. “Something happened on Venus that released a gigantic amount of gases into the atmosphere and could not be taken up again by the rock. That completely changed Venus, ”says Way.

The cause that led to the dramatic transformation of Venus remains a mystery to this day. Way and his colleagues suspect that a volcanic eruption on almost the entire planet could have been the trigger for the catastrophic greenhouse effect. One possibility is that large amounts of magma gushed into the air and carbon dioxide was released into the atmosphere from molten rock. The magma solidified before it reached the surface, creating a barrier through which the gas could no longer be reabsorbed. The large amount of carbon dioxide released then triggered a runaway greenhouse effect that resulted in today's searing average temperatures on the planet's surface.

Like Venus in the past, other exoplanets in the habitable zone could be life-friendly

“Our hypothesis is that Venus had a stable climate for billions of years. It is possible that the near-global surface renewal event is responsible for the transformation from an Earth-like climate to the hellish greenhouse we know today, ”says Way. On earth there are also examples of outgassing with far-reaching consequences, such as the formation of the Siberian trap 500 million years ago, which led to the worst mass extinction in earth's history. However, these events were not as extensive as they were on Venus.

Also Read: Astrophysicist Explains What Is Most Likely To Lead To The Demise Of The Earth

If the NASA researchers are correct, that doesn't just mean that Venus could once have been habitable. It could also mean that planets like Venus - which many researchers believe is beyond the inner limit of the habitable zone of our solar system - are not too close to the sun to harbor liquid water.

"Our models show a realistic possibility that Venus might once have been habitable and radically different from the Venus we know today," says Way. This could also have an impact on the assessment of exoplanets that are in the habitable zone. "It is quite possible that these planets also have liquid water and a temperate climate."