iridium 77 is 3-axis stabilized, with a hydrazine propulsion system. it has 2 solar panels with 1-axis articulation. the system employs l-band using fdma/tdma to provide voice at 4.8 kbit/s and data at 2.4 kbit/s with 16 db margin. the satellite has 48 spot beams for earth coverage and uses ka-band for crosslinks and ground commanding.