The unstable orbit of Phobos would seem to point towards a relatively recent capture.

Unfortunately, early unmanned surveys of the planet failed to note that Miranda's only moon had an unstable orbit.

Your vehicle is now in unstable orbit with increased transit time of zero point three seconds per unit of arc.

She's probably in unstable orbit around a double yellow star, but she may be able to patch herself up before the orbit breaks.

Comets are in unstable orbits that evolve over time due to perturbations and outgassing.

Such planets as do form about them often have relatively unstable orbits and are very rarely of a type that is reasonably habitable.

Few of these ancient moons survived, she added, because most were in unstable orbits.

However, signals around cataclysmic variable stars hinting for planets tend to match with unstable orbits.

They have unstable orbits due to the gravitational influence of the giant planets, and therefore must have come from elsewhere, probably outside Neptune.

Perturbations by Jupiter send bodies straying there into unstable orbits.