  Significant nonradial, nongravitational accelerations with magnitudes
incompatible with radiation-driven effects have been reported in seven small,
photometrically inactive near-Earth objects. Two of these objects exhibit large
transverse accelerations (i.e., within the orbital plane but orthogonal to the
radial direction), and six exhibit significant out-of-plane accelerations.
Here, we find that anisotropic outgassing resulting from differential heating
on a nucleus with nonzero spin-pole obliquity, averaged over an eccentric
orbit, can explain these accelerations for most of the objects. This balanced
outgassing model depends on three parameters -- the spin pole orientation (R.A.
and Dec.) and an acceleration magnitude. For these "dark comets" (excepting
2003 RM), we obtain parameter values that reproduce the observed
nongravitational accelerations. We derive formulae for the component
accelerations under certain assumptions for the acceleration scaling over
heliocentric distance. Although we lack estimates of these objects' spin axes
to confirm our values, this mechanism is nevertheless a plausible explanation
for the observed accelerations, and produces accurate perturbations to the
heliocentric motions of most of these objects. This model may also be applied
to active objects outside of the dark comets group.
