Space object identification via polarimetric satellite laser ranging

Low Earth orbits are becoming congested. The rapid identification and precise orbit determination of space objects is mandatory for space management. Satellite laser ranging (SLR) enables precise orbit determination by measuring the two-way photon travel time of laser pulses from a ground station to satellites equipped with retroreflectors. Here we propose polarization-modulated SLR, where specially designed retroreflectors positioned on a satellite switch the polarization state of received polarized photons and reflect them back to a ground station for analysis. Satellite identifiers can be coded into arrays of reflectors with different polarizing properties, while the orbit determining capability of conventional SLR is maintained. We design, build and test polarized light-switching retroreflector assemblies and investigate the feasibility of accurate signal measurement from SLR ground stations. The approach is passive, straightforward to integrate and requires no electricity. Polarization-modulated SLR could contribute to increasing demands of space object monitoring, for example of mega-constellations or during cluster launches.