Thus, a new Nasa project gets off the ground which, among other things, will use powerful electronic computers to process the information transmitted by a revolutionary probe: Magellan. The radar on this probe can distinguish objects with dimensions of just 130 meters and the on-board instruments, by analyzing the intensity of the radar beam, will make it possible to discover the chemical and physical nature of the surface. But there's even more: by completing hundreds of orbits around Venus, Magellan will be able to observe the same point on the ground from different angles. The computers will then do the rest: combining the data supplied by an altimeter, they create beautiful relief images which give the impression of gliding along the surface of the planet. Launched on May 4, 1989, the probe reaches Venus 15 months later, in August 1990 and immediately begins to send back incredibly clear and beautiful pictures: the panoramas displayed are the dream of any geologist, because they show an extraordinarily young world, which might be said to be still "in its infancy". In fact, no formation is more than one billion years old and, on the contrary, most of them is only 400 million years old, just like the Earth. A great difference compared to the Moon, Mercury and Mars, the other "solid" bodies of the solar system, whose surfaces were created at least 3 billion years ago! So, our sister planet does not only have a fiery atmosphere, but also an exceptional interior fire: Magellan has shown us that more than 80% of its surface seems to have been formed by volcanic activity and that probably all the rocks are the end result of such activity. Today, this planet is probably just like the Earth was at its very beginnings, 4 billion years ago, when its liquid and fiery surface had just transformed into a solid body enveloped by heavy layers of volcanic gas. However, geologically speaking, the two planets are quite different: the large number of volcanoes on Venus are scattered everywhere instead of being concentrated at the edges of the large tectonic plates like on Earth. And their dimensions vary greatly: from a diameter of less than 3 kilometers (there are hundreds of thousands) to more than 200 kilometers (and there are hundreds of this type). Their cones rise about the solidified lava plains which lead us to imagine the possibility of large reservoirs of magma located just below the surface instead of at great depths, like on our planet. In addition to "normal" volcanoes, Venus also has other unusual formations. Some of these include the so-called "arachnoids", more or less circular shapes surrounded by complex spider's web fractures produced perhaps by the expansion or contraction of the crust. They may have been created by a "hot point", an upthrow of magma from the mantel of the planet based on the same powerful mechanism which, on the Earth, created the Hawaiian islands. Instead, one of the real enigmas shown in the pictures from Magellan is what appears to be river beds with lengths of up to hundreds of kilometers. Since water is not present, they were probably formed by a very fluid lava flow, and in some cases this is possible. But one of them is truly unusual: 1 800 meters wide, it extends for no less than 7 000 kilometers, more than the Nile, which with a length of 6 611 kilometers is the longest river on the Earth. Since Venus' extremely dense atmosphere tends to cool molten rock very rapidly (like on the Earth how water cools faster than air at the same temperature), geologists have calculated that even super hot lava could only flow a maximum of 2 000 kilometers before coming to a halt. So what liquid could have carved out that "super-channel" that has no comparisons on any other planet? One possible explanation is that various lava sources capable of continuous eruptions may be distributed along the entire path: this would create a kind of immense "linear volcano". Other scars, which are easier to decipher, can also be found on the surface of Venus. These were produced by the impact of those wandering bodies, meteorites, which were quite numerous in the first billion years of life of our solar system. Planets and satellites were literally bombarded and so much so that they are covered by millions of craters of all shapes and sizes. Venus is different. On the surface, Magellan was barely able to "track down" a thousand craters, and all with a diameter of at least 3 kilometers and limited depth. Why? The reason seems to be, on one hand, the same atmosphere that surrounds the planet: it is so dense that it acts like a shield against cosmic meteors, breaking up and destroying the smallest ones and slowing down the larger ones just like the water in our oceans. On the other hand, their scarcity is additional proof of how much the volcanoes molded the face of the planet, continuously reshaping it and swallowing up all traces of the remote past.
Thus, a new Nasa project gets off the ground which, among other things, will use powerful electronic computers to process the information transmitted by a revolutionary probe: Magellan. The radar on this probe can distinguish objects with dimensions of just 130 meters and the on-board instruments, by analyzing the intensity of the radar beam, will make it possible to discover the chemical and physical nature of the surface. But there's even more: by completing hundreds of orbits around Venus, Magellan will be able to observe the same point on the ground from different angles. The computers will then do the rest: combining the data supplied by an altimeter, they create beautiful relief images which give the impression of gliding along the surface of the planet. Launched on May 4, 1989, the probe reaches Venus 15 months later, in August 1990 and immediately begins to send back incredibly clear and beautiful pictures: the panoramas displayed are the dream of any geologist, because they show an extraordinarily young world, which might be said to be still "in its infancy". In fact, no formation is more than one billion years old and, on the contrary, most of them is only 400 million years old, just like the Earth. A great difference compared to the Moon, Mercury and Mars, the other "solid" bodies of the solar system, whose surfaces were created at least 3 billion years ago! So, our sister planet does not only have a fiery atmosphere, but also an exceptional interior fire: Magellan has shown us that more than 80% of its surface seems to have been formed by volcanic activity and that probably all the rocks are the end result of such activity. Today, this planet is probably just like the Earth was at its very beginnings, 4 billion years ago, when its liquid and fiery surface had just transformed into a solid body enveloped by heavy layers of volcanic gas. However, geologically speaking, the two planets are quite different: the large number of volcanoes on Venus are scattered everywhere instead of being concentrated at the edges of the large tectonic plates like on Earth. And their dimensions vary greatly: from a diameter of less than 3 kilometers (there are hundreds of thousands) to more than 200 kilometers (and there are hundreds of this type). Their cones rise about the solidified lava plains which lead us to imagine the possibility of large reservoirs of magma located just below the surface instead of at great depths, like on our planet. In addition to "normal" volcanoes, Venus also has other unusual formations. Some of these include the so-called "arachnoids", more or less circular shapes surrounded by complex spider's web fractures produced perhaps by the expansion or contraction of the crust. They may have been created by a "hot point", an upthrow of magma from the mantel of the planet based on the same powerful mechanism which, on the Earth, created the Hawaiian islands. Instead, one of the real enigmas shown in the pictures from Magellan is what appears to be river beds with lengths of up to hundreds of kilometers. Since water is not present, they were probably formed by a very fluid lava flow, and in some cases this is possible. But one of them is truly unusual: 1 800
