Measuring the Lense-Thirring effect with Galileo?
- Beatriz Moreno Monge
GFZ German Research Centre for Geosciences
The precession of the orbital nodes of a particle orbiting a rotating mass is known as Lense-Thirring (LT) effect. The LT effect was first predicted by Einstein's General Relativity and it has been measured by using the LAGEOS satellites with an accuracy of 10%. The recent LARES experiment will allow a measurement of the LT effect with an uncertainty of a few percent. The main error in the measurement of frame dragging by a rotating mass using an Earth satellite is due to the uncertainties of the Earth's gravity field model, in particular in that spectrum represented by the even zonal harmonics of a spherical expansion and their time variations.
The arriving Galileo system will provide 27 new node observables for the LT effect estimation and their combination with the LAGEOS and LARES satellites will reduce the error introduced by the Earth's even zonal harmonics. However, the accuracy in the determination of the Galileo orbits and hence, in the estimation of their nodes drift, is limited mainly by the mismodeling of the solar radiation pressure (SRP).
Using simulated data we analyze the effects of mismodeling of the SRP and of the uncertainties in the Earth gravity field on the Galileo nodes drift measurement and propose an optimal parametrization for the LT estimation from the future Galileo data.