The Passive Reflectometry and Interferometry System (PARIS) concept involves a dedicated constellation of satellites picking up reflected satnav signals from GPS, Galileo and other navigation satellite constellations to gather data on Earth's sea and land surfaces. Operating on the same basis and in a similar way as current radar altimeters and scatterometers, these returning signals can be used to build up global maps of sea-surface height and wind and wave measurement over the ocean, determine ice extent and thickness of the icecaps and indicate soil moisture and biomass across land.

PARIS was devised by ESA engineer Manuel Martín-Neira, who is currently working with a team at ESA's ESTEC technical centre that includes Salvatore D'Addio on theoretical background, performance and data processing, Justo Alcazar in procuring General Support Technology Programme funding through contacts with national delegations, Philip Willemsen and Frédéric Teston, together with Ilaria Roma on mission studies, Rafaelle Vitulli on the correlator unit, Christopher Buck on previous experiments with an earlier breadboard, Petri Piironen on the electronics, Giovanni Toso on the antenna, Roberto Prieto and Nicolas Floury on ionospheric propagation effects and Nikos Karafolas on the optical harness.