Phobos 2 Phobos 2 Phobos 2 was the last space probe designed by the Soviet Union. It was designed to explore the moons of Mars, Phobos and Deimos. It was launched on 12 July 1988, and entered orbit on 29 January 1989. "Phobos 2" operated nominally throughout its cruise and Mars orbital insertion phases on 29 January 1989, gathering data on the Sun, interplanetary medium, Mars, and Phobos. "Phobos 2" investigated Mars surface and atmosphere and returned 37 images of Phobos with a resolution of up to 40 meters. Shortly before the final phase of the mission, during which the spacecraft was
Stability of the Solar System essentially the distance from sun to earth). These are now known as the Kirkwood gaps. Some asteroids were later discovered to orbit in these gaps, but their orbits are unstable and they will eventually break out of the resonance due to close encounters with a major planet. Another common form of resonance in the Solar System is spin–orbit resonance, where the period of spin (the time it takes the planet or moon to rotate once about its axis) has a simple numerical relationship with its orbital period. An example is our own Moon, which is in a 1:1 spin–orbit resonance