[gary]

Originally Posted by Matteo Rini, Physics APS, 4 Dec 2018

Two satellites erroneously placed in elliptical orbits have been used to test general relativity with unprecedented precision.

In 2014, two satellites of the Galileo European Global Navigation Satellite System were unintentionally launched on elliptical, rather than circular, orbits. This ellipticity created problems for their use in the global navigation network, but scientists turned this misfortune into an opportunity. Two independent teams, one led by Sven Herrmann at the University of Bremen in Germany and the other by Pacôme Delva, at both the Paris Sciences & Letters–PSL University and Sorbonne University in France, used clocks on the satellites to perform the most precise tests to date of one aspect of general relativity: the gravitational redshift of a clock’s frequency.

Articles here :-
https://physics.aps.org/synopsis-for...ett.121.231102

and here at Science :-
https://www.sciencemag.org/news/2018...ory-relativity