Extreme sister of the Earth. Past and Future of the Morning Star
Venus, being the brightest planet in the earth's firmament, deservedly bears the name of the beautiful goddess of love of the ancient Romans. But at the same time, it was one of the most annoying disappointments of scientists at the dawn of the space age. The hypothetical tropical paradise actually turned out to be a clear model of meteorological conditions in the biblical hell.
Below under the cut, we will try to figure out what space and geological processes have predetermined such a big difference between Venus and her sister Earth. And also, what actions of mankind in the future can return the status of a tropical paradise to the "morning star".
For the first time, direct data on the physical conditions on Venus were obtained from the flight path of the American station Mariner 2, back in 1962. AMS confirmed the theory of extreme conditions at the Morning Star, namely the practical absence of a magnetic field, a very hot atmosphere (up to + 500 ° C) and extremely long sunny days - up to 120 Earth days. Later, the planet became the object of close attention of the Soviet space program, which unofficially secured the status of “Russian patrimony” for Venus. The trend began in the 18th century, the Russian scientist Mikhail Lomonosov, who actually discovered the atmosphere of the planet.
“When Venus came out of the Sun, when its front edge began to approach the solar edge and was (as you can easily see with an eye) about a tenth of Venus’s diameter, then a worm appeared on the edge of the Sun, which became more distinct as the Venus came closer to the speech. Soon, this pimple was lost, and Venus was suddenly without an edge. " May 26, 1761
In the 60s, it was assumed that the atmospheric pressure on the surface of Venus ranges from 10-20 atmospheres, so the first Soviet landing stations (Venus 3, 4, 5 and 6) were crushed even at altitudes of 25-30 km. And only the Venus 7 station , created with the expectation of “survivability” at 540 ° C and a pressure of 150 atmospheres, was able for the first time in history to make a soft landing on the surface of another planet in the 70th year. Data on the conditions in the atmosphere of Venus have been radically revised. The pressure is estimated at 90 atmospheres and the temperature at 480 ° C. The “descendants” of this station - Venus 9 and 10, already in the 75th year will transmit the first panorama of the surface of another planet in history.
AMS Venus 9 landing test flight test
Panoramic shots of the surface of Venus. Correspondingly, the landing stations Venus 9, 10, 13 and 14. Venus 11 and 12 also landed and worked normally for more than 100 minutes, but they could not transmit the images.
The atmosphere of Venus, along with the Soviet stations, was studied by the American stations Pioneer-Venus 1 and 2 The measurements estimated the chemical composition of the atmosphere as 97% CO2, 2% Nitrogen and 0.1% oxygen. The diameter of the planet is 12104 km, the mass is 81.2% of the earth. “Powerful cloudiness” covering the surface from sunlight, turned out to be a porous haze of 80% sulfuric acid, extending at heights of 50-70km and reflecting up to 75% of the sunlight received by the planet.
Animation of the rotation of the cloud layer of the planetmaking a complete revolution in 4 earth days. Despite such a “global hurricane” in the upper atmosphere, wind gusts on the planet’s surface do not exceed several meters per second. On the right is the atmospheric circulation scheme of the planet.
In the 90s, using the Magellan spacecraft (NASA), a detailed radio mapping of almost the entire surface of Venus was carried out. Thanks to these data, as well as the work of the European probe "Venus Express", it became clear that the planet does not have plate tectonics, its surface is not older than 500 million years, and obviously it has lost a huge amount of water in the relatively recent past. This was evidenced by the large ratio of deuterium to water molecules recorded by Venus Express in the upper atmosphere.
Venus Express(ESA), twin sister of the Martian apparatus “Mars Express”, during the flight of the poles of Venus in 2012
On Earth, plate tectonics (causing the well-known “continental drift”) is an important cooling mechanism of our planet. The upper layer of the earth's mantle - the asthenosphere, due to the specifics of its structure and the influence of the earth's hydrosphere, has a lower degree of viscosity than the mantle, due to which lithospheric plates glide over the surface of the planet. Such a peculiar active “cooling system” creates a temperature difference between the mantle layers, greatly simplifying convection and heat transfer from the bowels to the surface. Already, in turn, in the center of our planet there is an iron-nickel core heated to 5700 ° C due to the decay of radioactive elements (the densest compounds in the formation of the planets descend to the center of the celestial body). Between it and the mantle is a shell of molten material rich in metals, due to convective processes, actively transferring heat from a solid core to the lower layers of the mantle. The convective motion in the molten shell in a compartment with the fast rotation of our planet (dynamo effect) creates a powerful magnetic field that protects our planet from solar radiation and prevents the Earth’s atmosphere from losing hydrogen and oxygen ions.
An interesting passage from the tectonics of plates of the Earth, clearly explaining their nature
The absence of active plate tectonics on Venus allows us to assume that heat transfer by the upper layers of the mantle of Venus is limited. There is no significant temperature difference between its layers, therefore a relatively uniform “overheating” of the inner regions of Venus occurs on the geological time scales. Presumably this happened 500 million years ago, when the planet got rid of excess heat through global tectonic activity that updated the entire surface of the planet. Indirectly, this is indicated by the fact that the planet does not have a magnetic field, although even the modern period of rotation is more than sufficient to generate a significant magnetic field, provided that convective processes in the liquid core are carried out (which is also supposedly absent from the planet).
It is worth mentioning that Venus has a so-called “false” magnetic field generated by the interaction of the solar wind and the planet’s ionosphere.
Such a difference in the composition of the atmosphere and the internal structure of both planets was most likely predetermined shortly after the appearance of both “sisters” from the gas-dust disk.
The internal structure of the Earth and Venus
According to the generally accepted hypothesis, the Earth at the dawn of its existence experienced a catastrophic collision with a large planet the size of Mars, which led to the appearance of our satellite - the Moon. This event was not at all exclusive to our star system of that time. The surroundings of modern planets were literally flooded with large planetoids, now and then colliding with planets and arcs with a friend. At about the same time, a similar collision of Mars with a planetoid 2000 km in diameter led to the appearance of a gigantic northern plain. Mercury, in turn, has a “too” massive iron core for the terrestrial planets, and allegedly suffered a collision with a large planetoid or a planet that deprived it of up to half the mass.
Simulation of an ancient collision of the Earth with the planet Teia
For Earth, a collision with the planet Teia had no lethal consequences. The planet collided with the Earth tangentially, in the direction of the daily rotation of the Earth, which gave it an additional rotation moment of about 5 hours, the inclination of the axis of rotation changed by 23.44 °. Up to 1.3% of the Earth’s mass was thrown into orbit at an altitude of 60,000 km, on which the present Moon has been formed over the course of a century. The longevity of the axial “stabilizer” of our planet was ensured by the fact that the Moon rotated in the same direction as the Earth, but much more slowly. Because of this, the tidal interactions of both bodies gradually moved the moon away from us, while simultaneously reducing the Earth's day. Today, these values have reached 385,000 km and 24 hours respectively.
The extremely slow diurnal rotation of Venus is very difficult to explain only by the tidal effects of the Sun and the Earth. Usually, during the formation of planets, especially large ones, the energy released during the accretion of matter partially passes into the energy of axial rotation. The daily rotation of almost all planets except Venus and Mercury is within 25 hours. Moreover, Venus rotates in the direction opposite to the axial rotation of the remaining planets. The exception is Uranus, which in antiquity supposedly survived a collision with a planetoid that literally sent the planet to a “knockdown” - Uranus, as you know, rotates lying on its side. To solve the riddle of such a slow diurnal rotation of Venus, the hypothesis of a giant collision was also put forward, which most likely fell tangentially in the direction opposite to the direction of rotation of the planet.
Huge clubs of fragments thrown into orbit of the planet could form a rather large satellite, comparable in size to the moon. However, since the satellite rotated in a retrograde orbit (in the direction opposite to the rotation of the planet), the tidal interaction of both bodies led to inhibition as the satellite itself and to a slowdown in the rotation of Venus. In the end, the satellite crossed the Roche limit, where the planet’s gravitational forces destroyed the satellite, and debris hit Venus. According to another model, the blow fell at such an angle that Venus literally turned upside down, having lost almost the entire moment of axial rotation.
A similar process is happening today between Mars and its satellite - Phobos. Since the red planet rotates more slowly than Phobos, the latter gradually loses its orbital moment, and is supposed to fall on Mars over the next 11 million years.
The extremely slow rotation of Venus does not allow anything to linger (in a geologically long time) in its orbit. According to one hypothesis, the “culprit” of such a meeting could be Mercury, which supposedly lost most of its mass from a collision with a planet mass with Venus . This hypothesis more easily explains two points at once - where did the “excess” mass of Mercury go and where did the planetoid colliding with Venus “disappear”. The first formed, together with the debris of Venus, a large satellite, which then fell to the planet, and Mercury, having lost its orbital moment from the impact, moved to a lower orbit.
Mercury has a disproportionately large iron-nickel core relative to the mass of the planet. It also, due to the tidal influence of the Sun, generates the magnetic field of the planet, which is 100 times weaker than the Earth
The slow diurnal rotation of Venus led to overheating of the ancient Venusian oceans, the existence of which was confirmed by the Venus Express, and intensified the decomposition by the ultraviolet rays of the sun of water molecules into hydrogen ions and oxygen. Due to the extremely weak ancient magnetic field of the planet, hydrogen left the planet (dissipation), and the solar wind, freely reaching the planet’s atmosphere, only enhanced the effect by blowing light elements into space. Oxygen was bound to surface rocks, but even now its absolute mass in the atmosphere of Venus is inferior to the terrestrial atmosphere only three times. Saturation of the atmosphere of Venus with water vapor only increased the greenhouse effect, which already increased due to the atmosphere consisting of CO2. Such positive feedback in a geologically short time greatly heated the atmosphere of the planet. The hydrosphere has evaporated plate tectonics ceased, and processes that were not quite understood today led to a halt in convective processes in the core of the planet. Venus has lost the already weak magnetic field, if it ever had a planet.
A modern map of Venus, compiled from the work of the orbital radars of the Pioneer-Venus , Venus 15, 16 and Magellan stations. About 4 billion years ago, the Earth received from the young sun only 70% of the energy that it receives today. Therefore, unlike Venus, the greenhouse effect given then by CO2 and methane (of biogenic origin) contained in the atmosphere played rather a positive role, preventing the ancient oceans from freezing. In turn, the fast daily rotation of our planet did not allow these oceans to overheat.
Subsequently, the level of greenhouse gases steadily fell in parallel with the increase in energy received by the Earth from the Sun. To date, almost all of the primary CO2 has been processed into carbonate deposits and biomass. The hydrosphere of the planet was eventually preserved, and with it the plate tectonics. Despite the faster rotation of the planet (4 times faster than today) and more active convection processes in the core and mantle in antiquity, the current magnetic field of the Earth is about twice as powerful as its ancient predecessor .
The Taming of the Shrew
Hypothetical view of terraformed Venus Because of the extremely difficult climatic and geological conditions on the planet, it is proposed to use a combined approach for its development: 1. To carry out an accurate bombardment of the planet, preferably with iron asteroids, to reduce the duration of a sunny day, as well as to “clear” the atmosphere of sulfuric acid vapor . Bombardment is carried out precisely by a large number of medium-sized asteroids, in order to avoid destruction of the planet's crust.
2. Installation of a huge screen at the Lagrange point L 1 of the planet, which prevents sunlight from reaching Venus, which will lead to cooling of the atmosphere and the loss of all CO2 in the form of “dry ice”. The second option involves only lowering the temperature to an acceptable level, for delivering large amounts of water to the surface - at a pressure of 90 bar, the water does not boil to a temperature of 300 ° C.
After cooling the planet, such a shield could be divided into several elements and rotate around the Lagrange point L 1 in such a way as not to prevent sunlight from reaching the atmosphere of the planet. In the early stages of terraforming, such characteristics of the shield could control the amount of solar radiation reaching Venus and at the same time generate a huge amount of energy (when assembling the screen from photovoltaic converters).
3. After water is delivered to Venus, most likely by bombardment by comets (they will require several tens of thousands, or about 100,000 comets the size of the core of Halley’s comet), it will be necessary to maintain high atmospheric pressure until the temperature of the atmosphere drops to the optimum, sufficient for the next step.
The second option involves first cooling the planet to an acceptable temperature, and only then carry out a cometary bombardment, which would simultaneously solve two problems - water delivery and promotion of the planet.
4. One way or another, for human life on the surface of the planet, you will have to get rid of 99% of the mass of its very dense atmosphere (which is 4.85x10 ^ 17t!). For these purposes (possibly in addition to artificial purifiers of the atmosphere) hyperextremophiles are well suited - the simplest archaea (or their future artificial modification), which can comfortably exist up to temperatures of 100 ° C. They can split the planet’s atmosphere into carbonate deposits (1.35x10 ^ 17t) and free oxygen (3.5x10 ^ 17t). If we deliver 3.85 x 10 ^ 16 tons of hydrogen to Venus and combine it with all this "excess" oxygen, we will get enormous masses of water that make up 1/3 of the mass of the Earth's oceans!
5. To protect these oceans and future life from streams of solar radiation, an artificial magnetic field of the planet will be created, one of the options involves placing cables from a superconductor along the equator of Venus.
6. The last stage, most likely, will consist in the subsequent cooling of the planet, the final “adjustment” of physical characteristics, the composition of the Venusian atmosphere and the creation of the biosphere, and artificial life can make a significant contribution to any of the 6 stages of terraforming.
Estimated map of the Venusian hydrosphere after completion of terraforming processes
All of the above requires a much more advanced level of science and technology, knowledge of the fundamental principles of planetary planetology, geology and genetics, inaccessible in our time. It is possible that today's assumptions about the methods of terraforming the planets will seem somewhat naive to our descendants, or, conversely, some points will turn out to be prophetic.
You and I can only hope that a man in some age will cancel the harsh sentence imposed by his mother by the nature of this “Goddess of Beauty”.
If you are interested in the subject of Venus research, then I advise you to familiarize yourself with the following works: A
NEW EPOCH IN A STUDY OF
Venus Venus or the first 60 kpx from another planet
Space Odyssey: Earth - Venus - Halley's comet (in the USSR they could write great)
Book about Venus