The Meridian series of communications satellites is reported to be the replacement for all the Molniya-1T, the Molniya-3 and Molniya-3K satellite series and possibly also for the communication component of the Parus. They are launched into highly eccentric Molniya-orbits.
Meridian is the highly eccentric orbit (HEO) component of the Integrated Satellite Communications System (ISSS), where they work in conjunction with the geostationary Raduga-1M (Globus-M) satellites.
The bus structure is reportedly pressurized, possibly based on the Uragan-M bus. Meridian satellites carry three transponders operating in different frequency bands.
The first two satellites were launched on Soyuz-2-1a Fregat boosters, afterwards the improved Soyuz-2-1a Fregat took over. The fifth satellite was an exception, which used a Soyuz-2-1b Fregat booster inherited from another program. Launch site was the Plesetsk cosmodrome.
The second launch reached only a 290 km × 36460 km × 62.8° orbit, indicating a Fregat failure during the end of the second burn, with the third burn not taking place. Nevertheless, the satellite is operational in this lower than planned orbit. The fifth launch failed to reach orbit.
The Meridian series was to end with the seventh launch. It was to replaced by a new series beginning in 2016, which will feature unpressurized busses. Instead, in February 2016, a new batch of four similar but slightly improved Meridian-M satellites was ordered, with the first to be launched in 2018.
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