General Relativity in Space and Sensitive Tests of the Equivalence Principle

TL;DR

This paper reviews space missions designed to test fundamental aspects of general relativity, including the equivalence principle, gravitational redshift, and Lorentz invariance, highlighting technological advancements and experimental progress.

Contribution

It provides a comprehensive overview of space-based experiments testing key predictions of general relativity and discusses the technological innovations enabling these high-precision measurements.

Findings

Space missions have significantly improved the accuracy of tests of the equivalence principle.

Technological advancements have enabled more precise measurements of relativistic effects in space.

A variety of current and planned experiments aim to explore fundamental gravitational physics.

Abstract

An introduction into the fundamental quests addressed in space missions is given. These quests are the exploration of the relativistic gravitational field, the Universality of Free Fall, the Universality of the Gravitational Redshift, Local Lorentz Invariance, the validity of Einstein's field equations, etc. In each case, the correspoding missions take advantage of the space conditions which are essential for the improvement of the accuracy of the experiments as compared to experiments on ground. A list and a short description of past, current and planned projects is given. Also the key technologies employed in space missions are addressed.