The proper functioning of the Global Positioning System (GPS) is directly dependent upon the accuracy of satellite measurements as supported by the GCRS.
Both systems incorporate standards that enable the consistency and ready comparability of the resulting spacetime coordinates among astrometric measurements taken worldwide.
This stable point for gravity helps to minimize relativistic effects from any observational frames of reference within the Solar System.
That is, their axes are aligned with that of the International Celestial Reference Frame (ICRF), which was adopted as a standard by the IAU two years earlier (1998).
The motivation of the ICRF is to define what "direction" means in space, by fixing its orientation in relation to the Celestial sphere, that is, to deep-space background.
That satellite took copious stellar parallax measurements at accuracies exceeding anything otherwise available at the time, thus producing a catalog of stars still in wide use today.
[1] The orientation of the BCRS/ICRS axes also align within 0.02 arcsecond of the Earth's mean equator and equinox for the Fifth Fundamental Catalog (FK5) J2000.0 epoch.