30th anniversary in orbit
January 10, 2019 marked 30 years since the launch of the first Etalon – a spacecraft designed by ISS-Reshetnev Company.
The Etalon spacecraft was designed by ISS-Reshetnev Company for the development of the GLONASS satellite navigation system. The spacecraft’s name (Etalon in Russian means “gold standard” or “benchmark”) speaks for itself – Etalon serves to provide some kind of a reference model of an object’s natural flow in Medium Earth orbits, those where GLONASS satellites are stationed.
Etalon is a geodetic passive satellite having a spherical shape and covered with reflecting corner cubes. Performed with the help of Etalon, laser ranging gave a more detailed information on navigation satellites’ motion on different parts of orbits, especially on those that were not “visible” for ground controllers. It helped substantially increase the accuracy of positioning services provided by the GLONASS navigation satellite system.
A total of two spacecraft of the Etalon family were built. Both of them were launched during 1989 together with Glonass satellites. Designed with a 5-year guaranteed life, the Etalon satellites today still carry out their mission – measure the Earth’s gravitational field and enable to determine its impact on various satellites and their performance.