If you had the opportunity to go backin time for 3 billion years and land on any planet in our solar system, then which place would you choose? Earth, with its barren continents and atmosphere unsuitable for breathing? Or maybe Mars froze through? What about Venus?
Venus now seems to be a hell of incarnation. The temperature of its surface, just think, 464 degrees Celsius. However, three billion years ago, this planet was arguably the most suitable habitat within the solar system, or at least the second after Earth. This hypothesis has been in the scientific community for a long time, but thanks to new climate models created by scientists from the Goddard Institute for Space Research, we have serious reasons to believe in it.
These models show that about 2 billion yearsback Venus could actually be a resort planet. Moderate terrestrial climate, acceptable temperature, liquid oceans of water. In fact, an ideal place, except for the increased level of radiation compared to the current level on Earth by about 40 percent. These models are built taking into account the difference in the speed of rotation of Venus.
“If Venus rotated faster in the past, thenmost likely the planet remained as lifeless as it is now, ”says Michael Wei, lead author of a new study published on the pages of the journal Geophysical Research Letters.
“But, with the right speed of rotation, the temperature on Venus would be very similar to Earth. And that’s what impresses me the most! ”
Level of suitability for living on Earth and Marsconstantly changing throughout the history of the solar system. Geological evidence indicates that Mars was once more moist in the distant past, but whether it was an ocean of liquid water or whether it was constantly covered with ice caps - this issue remains a subject of much debate. The land, in turn, went through the stage of degeneration from the greenhouse greenhouse to the ice and vice versa. All this time, oxygen was accumulating in her atmosphere, which made her more and more suitable for living complex life forms.
But what about Venus? Our closest neighbor and his level of habitability quite undeservedly attracted less attention from scientists, compared with Mars. Our little interest in this planet is very likely connected with what Venus is facing us now: a lifeless world, with an impenetrably dense atmosphere, toxic thunderclouds and atmospheric pressure are 100 times higher than on Earth. When the planet and its atmosphere can transform one space probe after another into molten goulash within a few seconds, it is understandable why people are very skeptical in its favor and decide to turn their attention to something else.
However, even if Venus is so strange andterrible today, this does not mean that she was always like that. The fact is that absolutely the entire surface of this planet has changed as a result of prolonged volcanic activity about 700 million years ago. And we do not know what it was before this time. Measuring the ratio of hydrogen isotopes in the atmosphere of Venus shows that there was once a lot more water on the planet. Perhaps there were so many that were enough for whole oceans.
“If we take a world similar to Venus, slowly rotating and located in a system of stars like the Sun, then this world is quite suitable for the existence of life, especially in the oceans.”
Therefore, trying to answer the question of whetherWhether Venus was once inhabited, Wei and his colleagues compiled information from a general topographic database collected using the Magellan spacecraft with data on estimates of water reserves and solar radiation levels typical of Venus in the past. All this information was loaded into global climate models similar to those used to model and study climate change on Earth.
The results were veryintriguing. Despite the fact that the ancient Venus received about 2.9 billion years ago much more sunlight than modern Earth, Wei's models showed that the average temperature on its surface was only 11 degrees Celsius. About 715 million years ago, the temperature rose by only 4 degrees. In other words, for more than 2 billion years, the temperature on the surface of the planet was suitable for the existence of life.
According to new research, powerful "electric winds" on Venus could cause evaporation of water from the planet’s atmosphere
However, there is one “but”. These figures are completely dependent on the past of Venus, according to which it has similar topographic and orbital characteristics of the "current version" of the planet. When Wei reconfigured his models, but made Venus 2.9 billion years old more like modern Earth, its surface temperature rose sharply.
“We wanted to see how a change in topography could affect the climate of this world,” says Wei.
“It turned out that the effect is very serious.”
The scientist notes that the reason for this may be changes in the amount of the reflex surface of Venus, as well as a shift in atmospheric dynamics.
Another interesting observation is related torotation of Venus. In the original computer models of Venus, 2.9 billion years old, Wei set the velocity of rotation equal to the current 243 Earth days. As soon as its circulation period was reduced to 16 days, the planet immediately "turned into a double boiler." This is due to areas of special circulation of the atmosphere of Venus on both sides of the equator.
“The earth has several areas of circulation,since our planet is spinning fast. However, if it spins slowly, then there will be only two areas: one in the north and one in the south. And this will greatly change the whole atmospheric dynamics, ”says Wei.
If Venus spins slowly, then rightunder the heliographic place of the star (that is, exactly that point on the surface where the sun's rays fall) huge greenhouse clouds will form. This will actually turn Venus into one giant solar reflector. If Venus spins faster, this effect will not occur.
This study does not provide a clear answer tothe question is whether Venus was once inhabited. However, it does provide an idea of the scenario in which it could be. It is worth noting that the speed of rotation of the planet with time can dramatically change. For example, our Earth slows down due to the gravity of the moon. Some scientists suggest that Venus spun much faster in the past. However, finding this out is an extremely difficult task. The most suitable solution is observing compact and Venus-like planets.
If we assume that Venus was indeed a habitable planet several billion years ago, then it is worth considering what kind of disaster led to what Venus is now?
“We need to collect and verify more data before we can say more,” says Wei.
The scientist adds that worlds like Venus should not be considered a priori as uninhabited.
“If we talk about the habitable zone of the star, then Venus is usually considered beyond,” says the scientist.
“For modern Venus, this observation is true. However, if a world similar to Venus would be located at the sun-like star and at the same time possess a lower rotation speed, then this world would definitely be suitable for the existence of life, especially in the oceans, if there were any. ”
Scientists believe that the current Venus cancontain many secrets about the nature of life on Earth. We learned from meteorites that there was a transfer of material between Mars and the Earth, which in turn made astrobiologists wonder if the Red Planet could “sow” Earth with life. If a similar opinion holds true for Venus, then this planet also needs to be added to the list of potential incubators of earthly life. Surprisingly, we still do not know if there are meteorites from Venus on Earth. First of all, because we still had no opportunity to analyze the Venusian breed and compare it with the earth.
In general, we cannot immediately deny the possibility that this acid bath, which Venus is now, could be the birthplace of our oldest ancestors.
“It is entirely possible that life in the solar system began with Venus and then moved to Earth. Or maybe the other way around, ”says Wei.