Testing MOND/TEVES with LISA Pathfinder

TL;DR

This paper proposes using the LISA Pathfinder spacecraft to experimentally test MOND/TEVES theories by detecting anomalous gravity gradients near the Sun-Earth saddle point, potentially confirming or refuting these modified gravity models.

Contribution

It introduces a novel experimental approach using LISA Pathfinder to directly test non-relativistic MOND phenomenology in space.

Findings

LISA Pathfinder can detect MOND gravity gradients if they exist.

A lunar fly-by strategy optimizes the mission's reach to the saddle point.

A null result would challenge the validity of TEVES/MOND theories.

Abstract

We suggest that LISA Pathfinder could be used to subject TEVES, and in particular the non-relativistic MOND phenomenology it incorporates, to a direct, controlled experimental test, in just a few years' time. The basic concept is to fly LISA Pathfinder through the region around the Sun-Earth saddle point, following its nominal mission, in order to look for anomalous gravity gradients. We examine various strategies to reach the saddle point, and conclude that the preferred strategy, resulting in relatively short transfer times of order one year, probably involves a lunar fly-by. We present robust estimates of the MOND gravity gradients that LISA Pathfinder should be exposed to, and conclude that if the gradiometer on-board the spacecraft achieves its nominal performance, these gradients will not just be detected, but measured and characterised in some detail, should they exist. Conversely, given the large predicted signal based on standard assumptions, a null result would most likely spell the end of TEVES/MOND.