Jupiter, Saturn and the Pioneer anomaly: a planetary-based independent test

In this paper we use the ratio of the corrections to the standard Newtonian/Einsteinian secular precessions of the longitudes of perihelia of Jupiter and Saturn, recently estimated by the Russian astronomer E.V. Pitjeva by fitting almost one century of data with the EPM ephemerides, to make an independent, planetary-based test of the hypothesis that the Pioneer anomaly (PA), as it is presently known in the 5-10 AU region, is of gravitational origin. Accounting for the errors in the determined apsidal extra-rates and in the values of the PA acceleration at the orbits of Jupiter and Saturn the answer is negative. If and when the re-analysis of the entire Pioneer 10/11 will be completed more firm conclusions could be reached. Moreover, it would also be important that other teams of astronomers estimate independently their own corrections to the perihelion precessions.

💡 Research Summary

The paper addresses the long‑standing puzzle of the Pioneer anomaly (PA), an unexpected, approximately constant sunward acceleration of about 8.74 × 10⁻¹⁰ m s⁻² that was inferred from Doppler tracking of the Pioneer 10 and 11 spacecraft in the 5–10 AU region of the solar system. While many explanations have been proposed, a particularly intriguing hypothesis is that the anomaly might be of gravitational origin, i.e., that an additional, distance‑independent acceleration acts on all masses in the outer solar system. If this were true, the same acceleration should leave a measurable imprint on the orbital motions of the giant planets, especially Jupiter and Saturn, whose orbits have been tracked for nearly a century.

To test this idea, the author uses the most recent determinations of the anomalous secular precessions of the planetary perihelia (the so‑called “extra‑rates”) obtained by the Russian astronomer E. V. Pitjeva. Pitjeva fitted almost 100 years of optical, radar, and spacecraft ranging data with the latest version of the EPM (Ephemerides of Planets and the Moon) planetary theory. The resulting corrections to the standard Newtonian/Einsteinian perihelion precessions are

• Jupiter: Δ𝜔̇_J = +0.006 ± 0.036 arcsec century⁻¹,
• Saturn: Δ𝜔̇_S = ‑0.92 ± 0.29 arcsec century⁻¹.

If a constant extra acceleration A_P acts on a planet, the perturbative contribution to its perihelion precession can be derived from Gauss’ planetary equations. The resulting expression is Δ𝜔̇ = A_P √