Until now Nostradamus, ONERA's" sky wave" transhorizon radar, has used the atmosphere's stratification properties to detect objects well beyond the horizon. For this, Nostradamus ' radarwaves are reflected by the ionosphere, at altitudes between 100 and 300km, and make it possible to detect moving targets well beyond the horizon, from a few hundred to several thousands of kilometers away
This Ka-band, whose frequencies are at the boundary of the window of use of radarwaves through the atmosphere, promises unmatched performance for altitude measurement and resolution, from a single satellite, by day or by night, regardless of the weather conditions. The main objective of the mission was to become acquainted with" Ka-images", to discover in practice the layout of roads, forests, crops, the sea, etc., in anticipation of a future space mission for the environment
In order to check that it is indeed the plane that it was declared to be, the collaborating researchers are proposing to use radarwaves that are already present in the environment due to television, radio and mobile phone transmitter antennas, etc. "This detection by means of ' passive radar' does not require any authorization, which we would have had to obtain if we had set up our own radar transmitter" says Sylvain Azarian, who is in charge of this project called Automatic Target Recognition
Its principle is equivalent to that of radar (lidar is also sometimes called laser radar), using visible light or infrared radiation rather than radarwaves. Lidars transmit a powerful laser pulse into the atmosphere, where light interacts with particles and molecules in the air
