We have a planet near us that looks very much like our own. Venus and Earth are about the same size and formed from the same materials around the same star. Indeed, an alien astronomer observing these two planets from another star system at a distance of a few light-years from us would not see the difference between Venus and Earth. But if you know something about the conditions on the surface of Venus, you realize that it is not like the Earth at all. The temperature is like in a self-cleaning furnace, the atmosphere is made of carbon dioxide, sulfuric acid clouds. Not a heavenly place, to put it mildly. How is it that two planets so similar in composition and size, located next to each other in the same star system, turned out to be so different? This question concerns more and more planetary scientists. It motivates people to create concepts of missions to explore Venus. If scientists can understand why Venus has become what it is, it will bring more clarity to another interesting question: how unique our planet is. Is the Earth a rule? Or an exception?
Has there ever been a blue Venus?
Modern ideas about the past of Venus show a rather bright picture - some time ago there was much more water on the planet than it has now. It is possible that there were whole oceans. But as the Sun got brighter and hotter, the temperature on the planet rose, and so did the existence of water - it just vanished. Vaporized water filled the atmosphere of Venus. The planet became ill with the greenhouse effect and still cannot recover from it. Whether there have ever been tectonic processes on Venus, similar to what happens on Earth - it is unknown. For these processes, water is of key importance. And even if they were there, the greenhouse effect could stop them. But the end of tectonic processes does not mean the end of geological activity: significant reserves of the internal heat of the planet continue to heat magma, and it comes to the surface in the form of huge lava flows.
The age of the Venus surface is about 700 million years. The surface is, of course, very old, but it is still younger than that of Mars, Mercury or the Moon, whose surface age exceeds several billion years.
Exploring planet number two
Looking at the Venus of the past as a world rich in water is just a hypothesis. Planet scientists do not know what caused such radical changes in surface conditions. People, in general, know less about Venus than about other inner planets of the solar system. That's why it sets challenging and unique challenges for researchers. In the 21st century, two missions were organized to Venus.
"The Venus Express of the European Space Agency has been successfully operating for 8 years: from 2006 to 2014. The Japanese Space Agency's apparatus, called Akatsuki (or PLANET-C), also visited our neighbor, and although it faced some difficulties, it still operates in orbit. Between the 60s and 80s, 35 missions were sent to the planet! NASA's "Mariner-2" mission was the first in which it was possible to make a flight near Venus. This happened in 1962. The Soviet device "Venus-9" became the first device that managed to transfer images of a planet surface. And the first sounds from the surface were received from the Venus 13 spacecraft. The last mission of NASA to study Venus - the device "Magellan" - was launched in 1989. After 5 years, the device was thrown into the atmosphere, but before that, he was able to map with the help of radar almost the entire surface of Venus.
Return to Venus
Over the past few years, NASA has made several mission proposals to Venus. The last mission chosen is to send an octocopter to Titan, Saturn's satellite. But for our hot neighbor, too, something has been planned. The project is called VICI (Venus In situ Composition Investigations) and involves the study of Venus with the help of a landing gear. Scientists want to determine the composition of rocks and minerals in this harsh world. the formation of Earth-like planets near our stars. And Venus under the eternally shining sun will help us understand the fate of the Earth.