General information about Phobos

Phobos (Greek φόβος «fear") - one of two satellites of Mars. Was discovered by American astronomer Asaph Hall in 1877.

Phobos is located at a distance of 2.77 radius from the center of the planet Mars, and makes one revolution in 7 hours 39 minutes 14 seconds, that the faster rotation of Mars on its axis. As a result, the Martian sky, Phobos rises in the west and sets in the east.

Phobos rotates around its axis with the same period that around Mars, so it's always turned to the planet by the same party. Its orbit is inside the Roche limit, and the satellite did not go away just by his inner strength. Such an arrangement leads to an orbit that are broken rocks from Phobos, often leaving visible groove on the surface of the satellite. Tidal influence of Mars gradually slows the movement of Phobos, and in the future will lead to his downfall on Mars.

Dimensions of Phobos are 26,6 × 22,2 × 18,6 km, its surface is dotted with craters, the largest of which - Stickney - has a diameter of 9 km. Whether you hit that gave birth to him a little harder, Phobos likely simply to split. From the crater linked fault system and cracks.

shssledovanie Phobos

Phobos has been photographed in close-up by several spacecraft, whose main aim was to photograph Mars. The first was Mariner 9 in 1971, followed by Viking 1 in 1977, Mars Global Surveyor in 1998 and 2003, Mars Express in 2004 and the Mars Reconnaissance Orbiter in 2007 and 2008.

In 1988 he launched two automatic interplanetary station Phobos to study Mars and its satellites. One of the devices was lost 2 months after launch, the second successfully reached Mars and managed to fulfill part of the research program before contact with him anymore.

Another expedition to Phobos is scheduled for 2009 in the framework of the "Phobos-soil" of the Russian Space Agency.

Prediction of the two satellites

The assumption of the existence of two Martian satellites expressed shogann Kepler in 1610. It was based on the logic that if the Earth has one satellite, while Jupiter - four (known at that time), the number of satellites of planets with increasing distance from the Sun increases in geometric progression. By this logic, of Mars must have two satellites.

In the third part of Chapter 3 of "Gulliver's Travels" (1726) Jonathan Swift, which describes the flying island of Laputa, said that astronomers Laputa discovered two moons of Mars in orbit, equal to 3 and 5 Martian diameters c rotation period of 10 and 21.5 hours. In fact, Phobos and Deimos are located at a distance of 1.4 and 3.5 diameters from the center of the planet Mars, and their periods - 7.6 and 30.3 hours.