The unstable orbit of Phobos would seem to point towards a relatively recent capture.
The high eccentricity of the planet's orbit suggests that either the Kozai mechanism (there is an exchange between the inclination of a planet and its eccentricity) is at work, or that the planet's orbit was distorted by the unstable orbit of other planets that used to be part of the HD 154672 system.
Small lunar spacecrafts are especially affected by those unstable orbits because their limited mass leaves little to no fuel reserves for excessive orbit maintenance maneuvers.
Under the assumption that these objects are inactive comets, we can set an upper limit of ∼0.17 to the fraction of NEAs with Q>4.8au of cometary origin, but it could be even lower if the NEAs in unstable orbits listed before turn out to be bona fide asteroids from the main belt.
The study shows that new unstable orbits, in the first part of the group I and II orbits, are found.
Most models of Solar System formation show both KBOs and SDOs first forming in a primordial comet belt, whereas later gravitational interactions, particularly with Neptune, sent the objects spiraling outward, some into stable orbits (the KBOs) and some into unstable orbits, becoming the scattered disc.
Among other things, he says, researchers need to check whether Hamilton's tidal mechanism for driving the initial moons into unstable orbits would have worked so far from Saturn so long after they formed.
The global controller makes all the unstable periodic orbits vanish except a targeted periodic orbit.
Other small bodies travel in unstable orbits that cross the paths of one or more of the planets.
Meanwhile research into the control of chaos, in which unstable orbits embedded within chaotic motions are stabilized, has advanced over recent years.
