3. Applications

3.1 Links between geostationary relays (GEO-GEO)

Two or three geostationary relays, evenly distributed over the geostationary orbit, provide a permanent, very high-speed link in both directions. Distances between two satellites can vary from a few hundred kilometers to around 73,000 km: throughputs are generally very high, in the gigabit-per-second range, and the required bit error rates are of the order of 10 ^{– 9} . Another feature is the very long service life: 10 to 15 years of continuous operation. Acquisition systems are simplified because the viewing directions remain fixed; the forward pointing angle is fixed, at around 15 µrad (satellites located 120° apart in geostationary orbit). Pointing accuracy is not excessive: a few microradians....