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 2.1a version includes conversion from analog to digital flight control system and uprated engines on the booster and the first stage with improved injection systems. The new digital flight control and telemetry systems allow the rocket to launch from a fixed rather than angled launch platform and adjust its heading in flight. A digital control system also enables the launch of larger commercial satellites with wider and longer payload fairings such as the ST-type fairing. These fairings introduce too much aerodynamic instability for the old analog system to handle.
Progress Rocket Space Centre, formerly known as TsSKB-Progress, is a space science and aerospace research company which is known for manufacturing launch vehicles and satellites. Most notably, Progress Rocket Space Centre is the manufacturer of Soyuz launch vehicles.INFO WIKI