Lunar Laser Ranging, Gravitomagnetism and Frame-Dragging

TL;DR

This paper reviews the concepts of frame-dragging and gravitomagnetism, discusses experimental efforts to detect these effects, and highlights that Lunar Laser Ranging has not yet measured the intrinsic gravitomagnetic field of celestial bodies.

Contribution

It clarifies that current Lunar Laser Ranging experiments do not measure the intrinsic gravitomagnetic field, emphasizing the need for dedicated experiments to test this aspect of General Relativity.

Findings

Lunar Laser Ranging confirms some aspects of General Relativity

Current experiments do not measure intrinsic gravitomagnetic fields

Further experiments are needed for direct detection of gravitomagnetism

Abstract

During the past century Einstein's theory of General Relativity gave rise to an experimental triumph, however, there are still aspects of this theory to be measured or more accurately tested. One of the main challenges in experimental gravitation, together with the direct detection of gravitational waves, is today the accurate measurement of the gravitomagnetic field generated by the angular momentum of a body. Here, after a description of frame-dragging and gravitomagnetism and of the main experiments to detect these relativistic phenomena, we show that the fundamental tests of General Relativity performed by Lunar Laser Ranging do not, however, include a measurement of the intrinsic gravitomagnetic field generated by the angular momentum of a body.