Title: A comment on "A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model", by I. Ciufolini et al,
Abstract: Recently, Ciufolini et al. reported on a test of the general relativistic
gravitomagnetic Lense-Thirring effect by analyzing about 3.5 years of laser
ranging data to the LAGEOS, LAGEOS II, LARES geodetic satellites orbiting the
Earth. By using the GRACE-based GGM05S Earth's global gravity model and a
linear combination of the nodes $\Omega$ of the three satellites designed to
remove the impact of errors in the first two even zonal harmonic coefficients
$J_2,~J_4$ of the multipolar expansion of the Newtonian part of the Earth's
gravitational potential, they claimed an overall accuracy of $5\%$ for the
Lense-Thirring caused node motion. We show that the scatter in the nominal
values of the uncancelled even zonals of degree $\ell = 6,~8,~10$ from some of
the most recent global gravity models does not yet allow to reach unambiguously
and univocally the expected $\approx 1\%$ level, being large up to $\lesssim
15\%~(\ell=6),~6\%~(\ell=8),~36\%~(\ell=10)$ for some pairs of models.