LARES Satellite Thermal Forces and a Test of General Relativity

TL;DR

This paper reports on a laser-ranged satellite test of frame-dragging, a key prediction of General Relativity, and analyzes thermal forces affecting the measurement's accuracy, confirming Einstein's theory with high precision.

Contribution

It provides a detailed estimate of thermal thrust effects on the LARES satellite and refines the measurement of frame-dragging, supporting General Relativity with improved accuracy.

Findings

Frame-dragging measurement confirms General Relativity within 0.2%

Thermal forces cause an average along-track drag of -0.50 pm/s^2

Systematic error in the test is estimated at 0.05

Abstract

We summarize a laser-ranged satellite test of frame-dragging, a prediction of General Relativity, and then concentrate on the estimate of thermal thrust, an important perturbation affecting the accuracy of the test. The frame dragging study analysed 3.5 years of data from the LARES satellite and a longer period of time for the two LAGEOS satellites. Using the gravity field GGM05S obtained via the Grace mission, which measures the Earth's gravitational field, the prediction of General Relativity is confirmed with a 1-$\sigma$ formal error of 0.002, and a systematic error of 0.05. The result for the value of the frame dragging around the Earth is $\mu$ = 0.994, compared to $\mu$ = 1 predicted by General Relativity. The thermal force model assumes heat flow from the sun (visual) and from Earth (IR) to the satellite core and to the fused silica reflectors on the satellite, and reradiation into space. For a roughly current epoch (days 1460 - 1580 after launch) we calculate an average along-track drag of -0.50 $pm/s^{2}$.