  The outer Solar System object (486958) Arrokoth (provisional designation 2014
MU$_{69}$) has been largely undisturbed since its formation. We study its
surface composition using data collected by the New Horizons spacecraft.
Methanol ice is present along with organic material, which may have formed
through radiation of simple molecules. Water ice was not detected. This
composition indicates hydrogenation of carbon monoxide-rich ice and/ or
energetic processing of methane condensed on water ice grains in the cold,
outer edge of the early Solar System. There are only small regional variations
in color and spectra across the surface, suggesting Arrokoth formed from a
homogeneous or well-mixed reservoir of solids. Microwave thermal emission from
the winter night side is consistent with a mean brightness temperature of
29$\pm$5 K.
