Chapter

General Relativity and John Archibald Wheeler

Volume 367 of the series Astrophysics and Space Science Library pp 371-434

Date:

Gravitomagnetism and Its Measurement with Laser Ranging to the LAGEOS Satellites and GRACE Earth Gravity Models

  • Ignazio CiufoliniAffiliated withDip. Ingegneria dell’Innovazione, Università del Salento and INFN Sezione di Lecce Email author 
  • , Erricos C. PavlisAffiliated withJoint Center for Earth Systems Technology, University of Maryland, Baltimore County
  • , John RiesAffiliated withCenter for Space Research, University of Texas at Austin
  • , Rolf KoenigAffiliated withCenter for Space Research, University of Texas at Austin
  • , Giampiero SindoniAffiliated withGFZ German Research Centre for Geosciences
  • , Antonio PaolozziAffiliated withGFZ German Research Centre for Geosciences
  • , Hans NewmayerAffiliated withCenter for Space Research, University of Texas at Austin

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Abstract

Dragging of Inertial Frames and gravitomagnetism are predictions of Einstein’s theory of General Relativity. Here, after a brief introduction to these phenomena of Einstein’s gravitational theory, we describe the method we have used to measure the Earth’s gravitomagnetic field using the satellites LAGEOS (LAser GEOdynamics Satellite), LAGEOS 2 and the Earth’s gravity models obtained by the spacecraft GRACE. We then report the results of our analysis with LAGEOS and LAGEOS 2, and with a number of GRACE (Gravity Recovery and Climate Experiment) models, that have confirmed this prediction of Einstein General Relativity and measured the Earth’s gravitomagnetic field with an accuracy of approximately 10%. We finally discuss the error sources in our measurement of gravitomagnetism and, in particular, the error induced by the uncertainties in the GRACE Earth gravity models. Here we both analyze the errors due to the static and time-varying Earth gravity field, and in particular we discuss the accuracy of the GRACE-only gravity models used in our measurement. We also provide a detailed analysis of the errors due to atmospheric refraction mis-modelling and to the uncertainties in measuring the orbital inclination. In the appendix, we report the complete error analysis and the total error budget in the measurement of gravitomagnetism with the LAGEOS satellites.