The preservation of frozen volatiles over billions of years is primarily due to the extreme thermal stability found in deep space environments. In many regions of our solar system, such as Kuiper Belt objects or icy moons, the ambient temperature remains consistently below the sublimation point of most common volatiles like water, methane, and ammonia. This deep freeze ensures that the kinetic energy required to break molecular bonds and transition from a solid to a gas is rarely met.
To combat solar radiation, these materials are often protected by a process called surface crusting or regolith shielding. Layers of dust and processed ice form a protective mantle that absorbs high energy particles and ultraviolet rays, preventing them from penetrating into the interior. This outer layer acts as a buffer, shielding the pristine chemical composition located deeper within the body.
Regarding gravitational perturbations, most small icy bodies follow stable orbital resonances. While gravitational interactions can cause minor internal heating through tidal forces, this effect is often insufficient to cause significant volatile loss if the body is large enough to maintain structural integrity. The combination of extreme cold, protective surface layers, and stable orbital dynamics allows these ancient chemical records to remain intact since the formation of the solar system.
