What condition allows volatile ices like methane and ammonia to remain permanently frozen in the Kuiper Belt?

Answer

The Sun's greatly diminished thermal influence in this cold environment

The Kuiper Belt occupies a vast, cold outer shell where the Sun's thermal influence is greatly diminished, which preserves the volatile ices.

What condition allows volatile ices like methane and ammonia to remain permanently frozen in the Kuiper Belt?
locationSpaceastronomyobjectsKuiper Belt