Forthcoming Close Angular Approaches of Planets to Radio Sources and Possibilities to Use Them as GR Tests

TL;DR

This paper analyzes upcoming close approaches of planets to radio sources to evaluate their potential for testing general relativity, creating a catalog of events from 2008 to 2050, and calculating relativistic effects for various baselines.

Contribution

It provides a comprehensive catalog of future planetary approaches to radio sources and assesses their suitability for relativistic gravity tests.

Findings

Relativistic effects are measurable during planetary occultations and approaches.

Jupiter and Saturn offer the most significant relativistic effects.

A catalog of 2008-2050 events is created for experimental planning.

Abstract

During close angular approaches of solar system planets to astrometric radio sources, the apparent positions of these sources shift due to relativistic effects and, thus, these events may be used for testing the theory of general relativity; this fact was successfully demonstrated in the experiments on the measurements of radio source position shifts during the approaches of Jupiter carried out in 1988 and 2002. An analysis, performed within the frames of the present work, showed that when a source is observed near a planet's disk edge, i.e., practically in the case of occultation, the current experimental accuracy makes it possible to measure the relativistic effects for all planets. However, radio occultations are fairly rare events. At the same time, only Jupiter and Saturn provide noticeable relativistic effects approaching the radio sources at angular distances of about a few planet radii. Our analysis resulted in the creation of a catalog of forthcoming occultations and approaches of planets to astrometric radio sources for the time period of 2008-2050, which can be used for planning experiments on testing gravity theories and other purposes. For all events included in the catalog, the main relativistic effects are calculated both for ground-based and space (Earth-Moon) interferometer baselines.