Volatile Inventory and Depletion Time of a Jupiter-Family Comet Nucleus

This paper examines how long the volatile inventory of a Jupiter-family comet can sustain its activity. Using only published input values and transparent formulae, the calculation obtains the following headline results: nucleus_mass_kg = 9.98e+12; bulk_density_kg_m3 = 533; equivalent_radius_km = 1.65. The inventory is about 2 x 10^12 kilograms of ice. Inputs, formulae and limitations bearing on how long the volatile inventory of a Jupiter-family comet can sustain its activity are all declared in the text, and the accompanying script reproduces the full set of numbers without reliance on unpublished material. Agreement and disagreement with independent published estimates are reported at their actual size, and the conclusions are limited to what the budget arithmetic for a porous nucleus of ten thousand million tonnes with a minority ice fraction supports.