A Conventional Physics Explanation for the Anomalous Acceleration of Pioneer 10/11

TL;DR

This paper demonstrates that the anomalous acceleration of Pioneer 10/11 can be explained by non-isotropic thermal radiation effects based on spacecraft construction, reducing the need for new physics explanations.

Contribution

It provides a detailed calculation of known thermal radiation effects and models them over the mission duration, offering a conventional physics explanation for the anomaly.

Findings

Model fits the acceleration data from 5 to 71 AU

Overpredicts the decrease in acceleration by 9%

Supports thermal radiation as a primary cause of the anomaly

Abstract

Anderson, et al., find the measured trajectories of Pioneer 10 and 11 spacecraft deviate from the trajectories computed from known forces acting on them. This unmodelled acceleration can be accounted for by non-isotropic radiation of spacecraft heat. Various forms of non-isotropic radiation were proposed by Katz, Murphy, and Scheffer, but Anderson, et al. felt that none of these could explain the observed effect. This paper calculates the known effects in more detail and considers new sources of radiation, all based on spacecraft construction. These effects are then modelled over the duration of the experiment. The model provides a reasonable fit to the acceleration from its appearance at a heliocentric distance of 5 AU to the last measurement at 71 AU, but overpredicts by 9% the decrease in acceleration between intervals I and III of the Pioneer 10 observations. (For comparison, the two different measurements of the effect (SIGMA and CHASMP) themselves differ by 4% in interval III.) In any case, by accounting for the bulk of the acceleration, the proposed mechanism makes it much more likely that the entire effect can be explained without the need for new physics.