Planetary Radio Interferometry and Doppler Experiment (PRIDE) technique: A test case of the Mars Express Phobos fly-by

TL;DR

This paper demonstrates a high-precision radio interferometry and Doppler measurement technique using the Mars Express spacecraft during a Phobos fly-by, enhancing planetary system studies.

Contribution

It introduces a novel data processing approach combining Doppler and phase-referenced VLBI for spacecraft tracking in planetary missions.

Findings

Achieved 30 μm/s Doppler precision at 10s integration

Obtained ~50 m lateral position accuracy at 1.4 AU

Validated the PRIDE technique during a Phobos fly-by

Abstract

The closest ever fly-by of the Martian moon Phobos, performed by the European Space Agency's Mars Express spacecraft, gives a unique opportunity to sharpen and test the Planetary Radio Interferometry and Doppler Experiments (PRIDE) technique in the interest of studying planet - satellite systems. The aim of this work is to demonstrate a technique of providing high precision positional and Doppler measurements of planetary spacecraft using the Mars Express spacecraft. The technique will be used in the framework of Planetary Radio Interferometry and Doppler Experiments in various planetary missions, in particular in fly-by mode. We advanced a novel approach to spacecraft data processing using the techniques of Doppler and phase-referenced very long baseline interferometry spacecraft tracking. We achieved, on average, mHz precision (30 {\mu}m/s at a 10 seconds integration time) for radial three-way Doppler estimates and sub-nanoradian precision for lateral position measurements, which in a linear measure (at a distance of 1.4 AU) corresponds to ~50 m.