PARIS
A rain of satellite navigation signals is constantly falling to Earth and being bounced back to space. The prospect of employing these reflected signals for remote sensing is the focus on one ESA technology demonstration mission.
The proposed PARIS In-Orbit Demonstrator mission would test the Passive Reflectometry and Interferometry System (PARIS) concept. The satellite would include a double-sided 1.1m high-gain antenna to intercept reflected global navigation satellite system (GNSS) signals and extract data on changing contours of Earth’s land, sea and ice surfaces.
PARIS is in some ways a passive variation on an existing instrument called a radar altimeter, currently flying on ESA's Envisat and other Earth-observing satellites. But current altimeters only sample single tracks at a time. PARIS would measure multiple samples with a faster return time, rapidly compiling images of mid-sized ‘mesoscale’ phenomena such as ocean currents – or even tsunamis.
The PARIS In-Orbit Demonstrator would sample four points at once, building to 16 to 20 for an operational, full-sized satellite with a 2.4-m antenna. The more navigation signals the greater the potential performance – within a decade more than 150 GNSS satellites are planned.
The PARIS In-Orbit Demonstrator is one of the concepts being considered for flight as Proba-4.
