  Anderson, et al. (gr-qc/9808081) have recently reported the discovery of an
apparent anomalous, weak, long-range acceleration in the Pioneer 10/11 and
Ulysses spacecraft. I believe that this result can be explained by
non-isotropic radiative cooling of the spacecraft electronics through passive
radiators on the spacecraft surface. These radiators are preferentially placed
on the anti-solar side of the spacecraft to avoid heating by solar radiation.
The power transmitted through these radiator panels can explain the observed
acceleration within the observational errors.
