Mercury - a geologically active planet
The closest planet to the Sun is Mercury. Astronomers have spent many decades studying this planet, but there are still more questions than answers. On the other hand, a lot is also known about Mercury. For example, scientists know that the concentration of iron in the core of Mercury is higher than that of any other planet in the solar system. There are several possible explanations for this fact. The generally accepted theory suggests that initially the planet closest to the Sun had as many metals and silicates as an ordinary meteorite. At the same time, the mass of Mercury was 2.25 times greater than now.
But at the very beginning of its existence, Mercury collided with a certain large body, as a result of which most of the crust and mantle separated from the planet. Accordingly, the relative fraction of the core of Mercury has increased. This theory looks somewhat dubious after the elemental composition of the surface of Mercury was studied by the Messenger probe.
As it turned out, Mercury is rich in potassium. But this element should not be much on a planet that has experienced a major collision. In the course of a stroke sufficient to lose part of the crust and mantle, the planet should have become very hot, and potassium would simply have evaporated. Now scientists are trying to explain this fact. And while they are looking for an explanation, another feature of the planet has become clear: it turns out that it is still geologically active.
Astronomers have studied the latest images of the Messenger probe. The traces of recent tectonic processes are clearly visible in the photographs. And this indicates that geological processes are still taking place on Mercury.
"Messenger" (Mercury Surface, Space ENvironment, GEochemistry and Ranging - MESSENGER) - American automatic interplanetary station (AMS) for the study of Mercury . This probe transmitted a large amount of data to the Earth about the planet closest to the Sun. Before the “Messenger,” it was explored by yet another apparatus - “ Mariner-10". He flew around the planet in the 70s. Then managed to get photographs of almost half of the surface of Mercury. True, scientists did not receive data on the chemical composition or structure of the planet - this device was not equipped with the necessary instruments. The technologies of that time still did not allow the creation of relatively small probes with complex scientific instruments. In order to better study Mercury, NASA launched the “Messenger” in 2004.
This apparatus helped fill a number of gaps in the study of the planet. For example, in 2011 it turned out that the magnetic center is not located at all in the center of the planet, as, for example, the magnetic center of the Earth. It is shifted to the north, which causes the deformation of the magnetic field of Mercury. In addition, the Messenger discovered traces of volcanic activity. The presence of water ice in craters at the poles of the planet is also considered proven.
Thomas Watters from the Smithsonian Institution in Washington (USA) led the study of images of the planet, which were transmitted by the “Messenger” immediately before its destruction. At the end of 2014, the Messenger ran out of fuel , which made it impossible to correct the orbit. Gradually, the pericenter began to shift lower to the surface of Mercury. On April 30, 2015, the Messenger completed its mission, having crashed to the surface of the planet.
In the photographs, it was possible to consider the surface of Mercury in detail. In particular, scientists saw many faults that divide the flat regions of the planet into polygons. Previously, these faults were considered traces of the tectonic activity of the planet in its distant past. Planetologists believed that hundreds of millions of years ago, Mercury was cooling, its size was decreasing, and the surface was covered with bumps.
Messenger probe during assembly (source: NASA )
But it seems that these processes are happening now. The fact is that faults are also found in relatively young craters. If the planet was geologically dead hundreds of millions of years, then such traces simply could not appear. Therefore, Watters is convinced that even 50 million years ago, geological processes took place on Mercury. Most likely, they are happening now. True, this remains to be proved. Scientists hope to get new data from the BepiColombo probe. This probe goes to the first planet of our solar system two years later, in April 2018.
“The relative youth of the faults on the surface of Mercury means that this planet, like the Earth, is geologically active. Mercury continues to cool, and its surface is gradually changing, ”study participants write in their work.
If Mercury is truly a geologically active planet, then NASA can implement the project of landing on its surface a device equipped with a seismometer. This will help clarify the details of the activity of the bowels of Mercury. Scientists have yet to find out why the core of this small planet has not yet cooled down. The fact that the core is liquid proves the presence of a magnetic field on the planet.