Phobos will crash into Mars

The two moons of Mars are Phobos and Deimos.
These moons of Mars may well be captured asteroids from the main asteroid belt located between Mars and Jupiter.
Both satellites orbit very close to their planet, a few thousand miles of it, 9 377 km for Phobos and Deimos 23 460 km.
These two moons are linked to in March by the forces of tides and show always the same face to their planet, as does the Moon from Earth.
Because Phobos orbits Mars in 7:39, faster than Mars rotates on itself (24H36), the tidal forces are decreasing its orbital radius in a slow but steady pace of a few cm per year.
Since its orbit is below synchronous altitude in 20 to 40 million years, it is possible that Phobos crashes or crashes on the Martian surface.

NB: The names of its moons are an allusion to a Greek verse, "The God of war arrives, flanked by his two satellites (thugs) fear and terror" phobos is Greek for "fear", and Deimos 'terror'.

Image: Phobos is a highly irregular measures 27 × 21.6 × 18.8 km, it is also one of the smallest moons in the solar system. We see its crater Stickney feature, the bottom right of the photograph.

Phobos and Deimos are very similar to C-type asteroids , i.e. carbonaceous asteroids. Scientists still do not understand how the planet Mars could gravitationally capture both asteroids and bring in the equatorial plane of the red planet. The image below shows against the very irregularly shaped Phobos observed by the Mars Express spacecraft of the European Space Agency at a flyover March 7, 2010. You can see many intersecting paths and a series of craters that are aligned much of the surface of the moon of Mars. Phobos looks like a conglomeration of debris in orbit and its mass is not enough important for gravity to have transformed into a sphere. The Russian Space Agency (RosKosmos) declared the PHOBOS-GRUNT mission as the first priority of its space science program to explore Phobos. PHOBOS-GRUNT mission is a technology demonstrator designed to test the ability to land and take off from Phobos. The mission will perform in situ observations from April 2013 for over a year. It will collect samples to be returned to Earth for analysis in July 2014.