The Mysterious Formation Of Martian Moons Solved, Shaped From A Giant Collision

The formation of the two Martian moons, Phobos and Deimos, remained a mystery for decades. This puzzle was unraveled with two independent and complementary studies that showed that the Martian moons were fashioned from a giant collision.

The research was printed in the journal Nature Geoscience on July 4, 2016. It was in collaboration with researchers from Universite Paris Diderot and Royal Observatory f Belgium, the CNRS, Universite de Rennes and the Japanese Institute ELSI, according to Science Daily.

In one study, the team of French, Belgian and Japanese researchers have tendered a complete and coherent scenario for the formation of Phobos and Deimos. They have been formed following a collision between Mars and a primordial body one-third its size, 100 to 800 million years after the existence of the planet Mars.

The researchers explained that the debris from this collision formed a very wide disk around Mars, which was made up of a dense inner part composed of matter infusion and a very thin outer part primarily of gas. Inside this disk was a moon one thousand times the size of Phobos, which has since vanished. The gravitational interactions produced in the outer disk by this massive star apparently acted as a catalyst for the gathering of debris to form other smaller, more distant moons.

In the second study, which complements the first study, the researchers from CNRS/AIX-Marseille Universite were able to rule out the possibility of a capture on the grounds of statistical arguments based on the compositional diversity of the asteroid belt. They also showed that the light signature emanated by Phobos and Deimos is incompatible with that of the primordial matter that formed Mars. This indicated support with the collision scenario. From the light signature, they inferred that the satellites are made of fine-grained dust.

These two independent studies, which reveal the theory of giant collision, could explain why the northern hemisphere of Mars has a lower elevation than the southern hemisphere. These involve the Borealis basin, which is probably the remains of a giant collision, such as the one that in fine gave birth to Phobos and Deimos. It also indicates why Mars has two satellites instead of a single one just like in the planet Earth, which was also formed by a giant collision.

The Martian moons, Phobos and Deimos, were discovered in 1877 by Asaph Hall. Phobos and Deimos are named after the characters in Greek mythology. Both characters accompanied their father Ares, god of war, into battle. Ares was referred to as Mars to the Romans.