SCF-Test of a Galileo-IOV retroreflector and thermal-optical simulation of a novel GNSS retroreflector array on a critical orbit

Thorough laboratory measurements performed at INFN-LNF (Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Frascati), in the framework of the ETRUSCO (Extra Terrestrial Ranging to Unified Constellations) experiment, proved fundamental to characterize retroreflectors for GNSS (Global Navigation Satellite System) satellites. The standard test developed, SCF-Test, was important to outline the weaknesses of past retroreflectors payloads (in use on GPS, GLONASS and GIOVE A/B satellites). For the upcoming deployment of the Galileo constellation ESA requested, in 2010, a full SCF-Test campaign to characterize a prototype retroreflector of the first IOV satellites. We report the results of a standard SCF-Test and the test of a simulated orbit, called GCO (Galileo Critical half-Orbit). The experience gathered with the ETRUSCO experiment was important for the subsequent project, ETRUSCO-2, whose aim is to develop and measure, in a newly built facility, a full size array of retroreflectors to be deployed on GNSS constellations. Here we report preliminary concurrent thermal and optical simulations of a simulated array. A simplified structure of the array was subject to a simulated space environment in a GCO; the resulting temperature distribution inside each retroreflector, was the input of the optical software to determine the variation of the intensity, throughout the orbit, coming back at a ranging station. The goal is to limit as much as possible signal fluctuations with respect to current deployed arrays.