Lessons Learned from the Pioneers 10/11 for a Mission to Test the Pioneer Anomaly

TL;DR

This paper reviews the Pioneer anomaly observed in spacecraft data, discusses potential explanations, and outlines lessons learned for designing future deep-space experiments to determine its origin with greater accuracy.

Contribution

It provides a comprehensive analysis of the Pioneer anomaly, evaluates proposed explanations, and offers detailed lessons and design considerations for future missions to investigate the anomaly.

Findings

The anomaly is a small, constant sunward acceleration of approximately 8.74 x 10^(-8) cm/s^2.

Proposed explanations, including external and internal effects, cannot fully account for the observed anomaly.

Lessons learned inform the design of future experiments to precisely characterize and potentially resolve the anomaly.

Abstract

Analysis of the radio-metric tracking data from the Pioneer 10/11 spacecraft at distances between 20--70 astronomical units (AU) from the Sun has consistently indicated the presence of an anomalous, small, constant Doppler frequency drift. The drift is a blue-shift, uniformly changing with rate a_t = (2.92 +/- 0.44) x 10^(-18) s/s^2. It can also be interpreted as a constant acceleration of a_P = (8.74 +/- 1.33) x 10^(-8) cm/s^2 directed towards the Sun. Although it is suspected that there is a systematic origin to the effect, none has been found. As a result, the nature of this anomaly has become of growing interest. Here we discuss the details of our recent investigation focusing on the effects both external to and internal to the spacecraft, as well as those due to modeling and computational techniques. We review some of the mechanisms proposed to explain the anomaly and show their inability to account for the observed behavior of the anomaly. We also present lessons learned from this investigation for a potential deep-space experiment that will reveal the origin of the discovered anomaly and also will characterize its properties with an accuracy of at least two orders of magnitude below the anomaly's size. A number of critical requirements and design considerations for such a mission are outlined and addressed.