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Moons of Mars

Satellites of Mars

 Automatic translation  Automatic translation Updated June 01, 2013

Both moons of the planet are Phobos and Deimos (names pulled by the sons of the god Ares in antique Greece).
They orbit near the planet, in some thousand kilometers of this one. They are bound in Mars by the strengths of tides, always showing the same face in its direction. As Phobos orbits around Mars more quickly than turns the planet itself, the strengths of tides make decrease its orbital beam in a slow, but constant way, at the rate of 9 cm a year. In 20 in 40 million years, Phobos will crash on the Martian surface. Deimos, on the other hand, is taken away enough so that its orbit tends rather to go away, it in a infinitely slow way.


It is an allusion to a Greek verse, " The God of the war arrives, flanked by its two satellites (hired men) fear and terror " phobos mean in Greek 'fear', and Deimos 'terror'.




Deimos and Phobos is constituted by rocks rich in carbon and by ice (as the asteroids of type - C). Both are strewed with craters of impact as all the telluric objects of the solar system.
The orbit of Phobos is below the beam orbital synchronous. It gets up on the West, moves very quickly through the sky and goes to bed in the East, usually twice a day.
It is if near Mars where he cannot be observed over the horizon completely by the surface. Phobos is condemned because its orbit being below the synchronous height, the strengths of tides decrease gradually its orbital beam at the 1,8 meter rate by century.
In approximately 40 million years, it will break to form a ring around Mars or it will crash on its surface.

Phobos Lune de Mars
diameter 26,8×21×18,4 km
mass 1,070x1016kg
discovered in  august 20th 1877
discovered by Asaph Hall
distance of Mars 9 380 km



Deimos would be originally a primitive meteorite, because quite as Phobos, her composition differs from that of the Mars.
This moon would have formed in the external belt of asteroids between Mars and Jupiter, because its color and its density are close to asteroids of type C, common in this belt of asteroids.
It is a small rotating, very dark irregular body of shape there 30H18mn on its orbit in 23 460 km.
It is in synchronous rotation, presenting, quite as Phobos or the Moon, always the same in front of the planet.
Too close to Mars, he cannot any more be visible beyond the 82nd parallel.
Deimos seems smooth with its ground swamped with dust of regolith, no crater exceeds 3000 m of diameter.
The surface seems exempt of streak.
Considering his weak gravity 4.10-4g, due to his small size, a man would take off by jumping in 36 kph, what amounts to an escape speed of 10m/s.

Deimos Lune de Mars
diameter 15×12×10,4 km
mass 0,224x1016 kg
discovered in  august 17th 1877
discovered by Asaph Hall
distance of Mars 23 460 km

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