Light-time computations for the BepiColombo radioscience experiment

TL;DR

This paper discusses the modeling and numerical methods for light-time calculations in the BepiColombo radioscience experiment, crucial for precise planetary and spacecraft measurements considering relativistic effects.

Contribution

It introduces a detailed model of space-time coordinate transformations and numerical techniques to improve light-time computation accuracy for planetary missions.

Findings

Enhanced accuracy in light-time calculations

Effective numerical methods to reduce rounding errors

Improved modeling of relativistic effects in space-time

Abstract

The radioscience experiment is one of the on board experiment of the Mercury ESA mission BepiColombo that will be launched in 2014. The goals of the experiment are to determine the gravity field of Mercury and its rotation state, to determine the orbit of Mercury, to constrain the possible theories of gravitation (for example by determining the post-Newtonian (PN) parameters), to provide the spacecraft position for geodesy experiments and to contribute to planetary ephemerides improvement. This is possible thanks to a new technology which allows to reach great accuracies in the observables range and range rate; it is well known that a similar level of accuracy requires studying a suitable model taking into account numerous relativistic effects. In this paper we deal with the modelling of the space-time coordinate transformations needed for the light-time computations and the numerical methods adopted to avoid rounding-off errors in such computations.