giant Artist’s impression of the impact that would have spawned Phobos and Deimos. – Université Paris Diderot / Labex UnivEarthS
    • 07/05/2016 at 16:55
    • updated

Marseille team of scientists has just pierce mystery of the origins of the moons of Mars. Baptized Phobos (fear in Greek) and Deimos (terror), with reference to twin the god Ares had with the goddess Aphrodite, these two “heavenly bodies” revolve around Mars with two different orbits. So far, the origin of these two moons remained an enigma.

According to one theory, they would have formed simultaneously with Mars. A second scenario envisaged they would have been “captured” by Mars to make the satellites. In a third case, they would be born after a giant impact between Mars and planet embryos. The study conducted by Pierre Vernazza particular, researcher at the Marseille Astrophysics Laboratory (AML), reinforces the latter theory.



Dust Grains

By studying the composition asteroids, the young researcher of 37 years was able to demonstrate that the theory of the capture of asteroids is impossible because “no other celestial object has properties.” In addition, the “light signature” issued by Phobos and Deimos is incompatible with that of the “building blocks” of the red planet. In fact, these satellites, composed of very fine dust are like sponges, “with empty inside,” says Pierre Vernazza.

The study of LAM, which will be published in The Astrophysical Journal , was confirmed by the work of a Belgian-Franco-Japanese research team has developed a coherent story of the birth of these two moons. 100 to 800 million years after its birth, Mars was hit by a huge asteroid – about a third of its size. The collision would have caused a huge gas field.

On cooling, and under the effect of gravity, this gas would be turned into tiny dust grains measuring several tens of nanometers. Gradually, these grains are agglomerated to form a dozen small satellites and a huge moon. The latter would be settled on Mars under the effects of the attraction of the planet. In the end, only subsisted Phobos and Deimos, remote enough to withstand that force.



Timeline & # xe9; v & # xe9; events that would have given xe9 & #; & # xE0 birth, Phobos and Deimos.
Chronology of events that could have led to Phobos and Deimos. – Antony Trinh / Royal Observatory of Belgium

Soon as Philae

But why be interested in these celestial bodies so far? Because there is “four terrestrial planets in our solar system, said Pierre Vernazza (Mercury, Venus, Earth and Mars). And of those four, only two of them have moons: Earth and Mars. “Thus, by studying the conditions for the creation of these moons, scientists hope to learn a little about the birth of the solar system and therefore the Earth.

The next step in the discovery of two Martian moons will place in 2022. the Japanese Space agency (JAXA) has decided to launch an exploratory mission in March called Moons exploration (MMX) which will be responsible to bring samples of Phobos. Pierre Vernazza is one of the scientists working on the future explorer module that will act as Philae (aboard Rosetta) on the comet 67P. It will take as its return is not expected before 2027

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