Orbital effects of the time-dependent component of the Pioneer anomaly

TL;DR

This paper investigates how a recently identified time-dependent component of the Pioneer Anomaly could cause measurable secular changes in the orbits of planets like Saturn and Uranus, with potential implications for understanding gravitational effects in the solar system.

Contribution

It provides a detailed analysis of the orbital effects of the time-dependent Pioneer Anomaly component, highlighting potential observable signatures in planetary orbits.

Findings

Predicted orbital variations for Saturn and Uranus are 2-3 orders of magnitude larger than current measurement accuracies.

Such anomalies are unlikely to be hidden in existing data due to their large predicted sizes.

The maximum allowed constant acceleration component at 9.5 au is constrained to 9×10^-15 m/s^2 by perihelion precession data.

Abstract

We work out the impact that the recently determined time-dependent component of the Pioneer Anomaly (PA), interpreted as an additional exotic acceleration of gravitational origin with respect to the well known PA-like constant one, may have on the orbital motions of some planets of the solar system. By assuming that it points towards the Sun, it turns out that both the semi-major axis a and the eccentricity e of the orbit of a test particle experience secular variations. For Saturn and Uranus, for which modern data records cover at least one full orbital revolution, such predicted anomalies are up to 2-3 orders of magnitude larger than the present-day accuracies in empirical determinations their orbital parameters from the usual orbit determination procedures in which the PA was not modeled. Given the predicted huge sizes of such hypothetical signatures, it is unlikely that their absence from the presently available processed data can be attributable to an "absorption" for them in the estimated parameters caused by the fact that they were not explicitly modeled. The magnitude of a constant PA-type acceleration at 9.5 au cannot be larger than 9 10^-15 m s^-2 according to the latest observational results for the perihelion precession of Saturn.