It's time to fly to Venus

The space agencies have not given due attention to the most Earth-like planet in our solar system/Alexander Rudin

The article is published with the approval of Scientific American Israel and the Ort Israel network

Mars and Venus have been at the center of scientific and popular speculation since at least the beginning of the 20th century. And since the 60s, the countries active in space have sent robotic spacecraft to explore both worlds. But Mars has received far more attention. Every year since 2002 there have been at least two spacecraft actively collecting data on Mars.

This can be understood. Mars is much more hospitable than Venus, on whose surface the temperatures reach up to about 480 degrees Celsius, the pressure reaches 92 times that of the Earth and the sky is always covered with a thick mantle of sulfuric acid clouds. We have direct evidence that in the past water flowed and even accumulated on Mars. It is impossible to rule out the possibility that life once existed on it, and it is possible that it exists even today.

The planet Venus is much more similar to Earth in its dimensions (it is only 5% smaller than Earth), in its composition and the gravitational force acting on its surface, but the harsh environmental conditions do not leave much room for hope that life has ever existed there. But it is still worth studying Venus to learn why the planet got to this state, and how Earth can avoid a similar fate.

Venus can also help us understand the recently discovered planets outside the solar system. A surprising number of such planets reside close to their suns, which they orbit in very short cycles, up to a few days. Although so far most of these planets can be described as hot versions of the planets Jupiter and Neptune, improvement in measurement and observation instruments should allow astronomers to discover hot versions of Venus as well. If this does happen, our planetary sister could serve as a valuable point of comparison, which would allow us to interpret the observations on those distant worlds.

But Venus is also a fascinating world in its own right. Although it is similar in size and composition to the Earth, there is no evidence that it is operated by plate tectonics like the one that constantly recycles the Earth's crust. Even so, the surface of Venus is rich in volcanoes, lava flows and other evidence of tectonic activity. If tectonic activity is still occurring, and this is quite plausible, then its study may provide us with important information about the internal composition and dynamics of Venus.

The dynamics of Venus' atmosphere are equally fascinating. The planet rotates around its axis once every 243 days in the opposite direction to its rotation around the Sun, unlike any other planet. But the clouds orbit Venus in just four days, a phenomenon known as super-rotation. And in this fast swirl the entire atmosphere is actually involved, up to heights of 80 to 90 kilometers. The only unusual places are the poles, where spectacular eddies develop that constantly change shape. The movement of the atmosphere of Venus is therefore similar to a huge hurricane, on a planetary scale, with two "eyes", one at each pole. Scientists hope that studying the dynamics of Venus' atmosphere will help them understand how to predict and even control hurricanes on Earth.

In the eyes of the general public, the search for extraterrestrial life is perhaps the most important reason for planetary exploration. Does the hellish climate of Venus completely prevent any kind of biology? Surprisingly, some experts believe that the answer is negative. According to them, the aerosol particles common in the atmosphere of Venus may, in principle, support certain forms of life. All the essential ingredients are there: a moderate temperature regime at an altitude of 50 to 70 kilometers above the surface, liquid water and a rich chemical system. Only future studies will be able to determine whether this hypothesis, which sounds fanciful, is true or not.

And with all this scientific promise, and Venus' proximity to Earth, this planet has been comparatively little explored. In fact, the Venus Express spacecraft was launched to Venus in 2005, twenty years after the previous spacecraft. Only a tiny handful of spacecraft have been launched since then. For all these reasons, planetary scientists around the world believe the time has come for a new scientific mission to explore Venus, which will include orbiting spacecraft, landers and airborne platforms. We hope that the funding agencies will agree to this.

Alexander Rudin is a planetary scientist and lecturer at the Moscow Institute of Physics and Technology.