Space-based tests of gravity with laser ranging

TL;DR

This paper discusses how recent advances in laser ranging, quantum sensors, and drag-free technology enable highly precise space-based tests of gravity, including measurements of fundamental physics parameters and potential variations in gravitational constants.

Contribution

It highlights recent progress and future prospects for space-based laser ranging to improve tests of gravity and fundamental physics.

Findings

Enhanced accuracy in lunar and interplanetary laser ranging.

Potential for improved measurements of PPN parameters and G variation.

Development of optical architectures for centimeter to millimeter range accuracy.

Abstract

Existing capabilities in laser ranging, optical interferometry and metrology, in combination with precision frequency standards, atom-based quantum sensors, and drag-free technologies, are critical for the space-based tests of fundamental physics; as a result, of the recent progress in these disciplines, the entire area is poised for major advances. Thus, accurate ranging to the Moon and Mars will provide significant improvements in several gravity tests, namely the equivalence principle, geodetic precession, PPN parameters $\beta$ and $\gamma$, and possible variation of the gravitational constant $G$. Other tests will become possible with development of an optical architecture that would allow proceeding from meter to centimeter to millimeter range accuracies on interplanetary distances. Motivated by anticipated accuracy gains, we discuss the recent renaissance in lunar laser ranging and consider future relativistic gravity experiments with precision laser ranging over interplanetary distances.