Mercury, the planet, had volcanoes that ceased their activity 3.5 billion years ago, much faster than the other planets. The scientists wanted to know how this was possible.
The journal of Geophysical Research Letters published an article where researchers explain the geological evolution of the planet, which may also count for the transformations of other rocky worlds from space.
The results of the study confirm the traditional model of global cooling and contraction and their role in volcanism.
Volcanoes and Space Geology
The volcanic activity can either be explosive or effusive. The first type is similar to the eruption of the Mount St. Helens from 1980, which produced bursts of debris and ash. The second type is quieter, with lava pouring slowly over the landscape, and it probably created the planetary crust.
The researchers use volcanic deposits to draw conclusions on the geological background of a planet. The planets from our solar system that are closer to the Sun are made from the same materials. However, the timeline of their evolution is different.
There are quite some differences between planets when it comes to cooling off. Venus stopped its volcanic activity hundreds of million years ago, while Mars just a few million years. The Earth is still active, as many volcanoes are still erupting today.
Mercury, the Unexplored Planet
The planet is one of the less explored objects in space because it’s very close to the Sun and the power of our star’s gravitation pulls everything from the orbit of the planet. Scientists don’t have any geological samples from the surface of the globe, and all the data we have comes from the MESSENGER’s flyby.
The NASA probe was launched in 2004 and delivered photographs of the surface of Mercury. The images showed caves resulted from asteroid bombardments and volcanism.
The scientists used a mathematical model to estimate the age of the volcanoes on the planet and discovered that the eruptions stopped 3.5 billion years ago.
The explanation may be that the size of Mercury allowed it to cool off faster than other planets. Moreover, its mantle is much thinner than its core, which permitted a rapid evacuation of heat.
Still, the scientists do not know for sure that this is the case with Mercury. A confirmation would come from a sample from the surface, but all will have to wait until the BepiColombo mission which will launch in 2017 and will reach the planet after seven years of flight.
The BepiColombo mission is initiated by a partnership between the European Space Agency and the Japanese space experts. The probe will analyze the craters and investigate their origins, it will study the magnetic field and its atmosphere, and it will test the theory of general relativity.
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