  Pioneer 10 and 11 were the first probes sent to study the outer planets of
the Solar System and Pioneer 10 was the first spacecraft to leave the Solar
System. Besides their already epic journeys, Pioneer 10 and 11 spacecraft were
subjected to an unaccounted effect interpreted as a constant acceleration
toward the Sun, the so-called Pioneer anomaly. One of the possibilities put
forward for explaining the Pioneer anomaly is the gravitational acceleration of
the Kuiper Belt. In this work we examine this hypothesis for various models for
the Kuiper Belt mass distribution. We find that the gravitational effect due to
the Kuiper Belt cannot account for the Pioneer anomaly. Furthermore, we have
also studied the hypothesis that drag forces can explain the the Pioneer
anomaly; however we conclude that the density required for producing the
Pioneer anomaly is many orders of magnitude greater than those of
interplanetary and interstellar dust. Our conclusions suggest that only through
a mission, the Pioneer anomaly can be confirmed and further investigated. If a
mission with these aims is ever sent to space, it turns out, on account of our
results, that it will be also a quite interesting probe to study the mass
distribution of the Kuiper Belt.
