Ethane and carbon monoxide were detected in a short-period comet of probabl
e Kuiper Belt origin. Ethane is substantially less abundant compared with H
yakutake and Hale-Bopp, two comets from the giant-planet region of the sola
r nebula, suggesting a heliocentric gradient in ethane in precometary ices.
It is argued that processing by X-rays from the young Sun may be responsib