Relativistic Warning to Space Missions Aimed to Reach Phobos

TL;DR

This paper suggests that relativistic effects, specifically the time-delay effect, may explain discrepancies in Phobos' observed acceleration and orbital shifts, which could impact future space missions to Phobos and other fast satellites.

Contribution

It introduces a relativistic explanation for Phobos' orbital perturbations, highlighting the importance of relativistic effects in satellite motion predictions.

Findings

Relativistic time-delay effect explains Phobos' orbital anomalies.

Computed orbital shifts may threaten mission success for Phobos-Grunt.

Limits of relativistic accelerations predicted for fast Jovian satellites.

Abstract

Disagreement in estimations of the observed acceleration of Phobos yields several theories empirically modifying classical description of motion of the satellite, but its orbital positions detected by Mars-aimed spacecraft differ from predictions. It is shown that the satellite's orbital perturbations can be explained as manifestations of the relativistic time-delay effect ignored in classical models. So computed limits of Phobos' acceleration essentially exceed the experimental values. The satellite's expected orbital shift is calculated for the moment of contact with a landing module of the Phobos-Grunt project; the shift assessed in kilometers may prevent the mission success. Limits of the apparent relativistic accelerations are predicted for fast satellites of Jupiter.