A critical analysis of a recent test of the Lense-Thirring effect with the LAGEOS satellites

Abstract

In this paper, we quantitatively discuss the impact of the current uncertainties in the even zonal harmonic coefficients Jℓ of the Newtonian part of the terrestrial gravitational potential on the measurement of the general relativistic Lense-Thirring effect. We use a suitable linear combination of the nodes Ω of the laser-ranged LAGEOS and LAGEOS-II satellites. The one-sigma systematic error due to mismodelling of the Jℓ coefficients ranges from ∼ 4% for the EIGEN-GRACE02S gravity field model to ∼ 9% for the GGM02S model. Another important source of systematic error of gravitational origin is represented by the secular variations jℓ of the even zonal harmonics. While the relativistic and Jℓ signals are linear in time, the shift due to jℓ is quadratic. We quantitatively assess their impact on the measurement of the Lense-Thirring effect with numerical simulations obtaining a 10 - 20% one-sigma total error over 11 years for EIGEN-GRACE02S. Ciufolini and Pavlis (Nature 431:958-960, 2004) claim a total error of 5% at the one-sigma level. © Springer-Verlag 2006.