The spacecraft is built by EADS Astrium, Europe's leading satellite manufacturer, in collaboration with Russia's Khrunichev Space Center under a contract to Russian Space Communications Company.
The Express-AM4 mission will be the third Proton launch of 2011 and the 366th Proton flight overall.
The most powerful satellite ever built in Europe, Express-AM4 will be the 50th Eurostar spacecraft to reach geostationary orbit.
Express-AM4 Communications Satellite
Express-AM4 is a new powerful communications satellite built by Europe's satellite manufacturer Astrium in association with Russia's Khrunichev Space Center for Russian Space Communications Company, RSCC.
The Express-AM4 spacecraft is based on the highly successful Astrium's Eurostar E3000 satellite design. Since the launch of the first ever Eurostar in 1990, over 45 Eurostars have been successfully delivered to geostationary orbit, clocking up a total of nearly 400 years of service.
Express-AM4 has 63 active transponders operating in L, C, Ku and Ka bands. Its twelve antennas will provide high performance coverage over the Russian Federation and the CIS countries and its steerable antennas can be used to provide communication to any point within the satellite's field of view. With an electrical power of more than 16 kW, Express-AM4 is the most powerful satellite ever built in Europe.
Designed for 15 years of service, Express-AM4 will be positioned in geostationary orbit at 80° East longitude, Russia's key orbital communications location. RSCC is currently looking for high power satellites to complement its existing fleet and fulfill growing needs for satellite capacity. Express-AM4 is the first and major milestone in this ambitious program.
For parallel manufacture, the square-shaped satellite is based on the modular principle and consists of a service module and a communications payload, with the equipment mounted on aluminum honeycomb panels.
The service module is a standard Eurostar E3000 service module without a plasma propulsion system. Four identical propellant tanks are mounted around the module's cylinder-shaped body to fuel the liquid apogee engine that is fixed in the module's center and seven propellant assemblies that house main and redundant low thrust engines. The bipropellant propulsion system uses MON and N2H4 to accurately maintain the satellite's orbital position.
During the early stages of the mission and, if necessary, in emergency situations, the satellite will be contacted and controlled via directional antennas by two sets of C-band receivers and amplifiers. Once Express-AM4 enters service, it will use the payload's omni antennas for communication. The craft's software can support up to 30 days of autonomous flight.
Express-AM4 is powered by two wings of solar arrays, each having five panels of triple junction GaAs cells, and two Li-Ion batteries, offering end-of-life power of 8.5 kW.
Temperature control is provided by heat pipes routed on the north and south consoles. Heaters are operated automatically or by command.
The satellite's orientation is determined by two earth sensors, seven sun sensors and two gyroscopes and is controlled by four reaction wheels. Express-AM4's communications payload includes:
- 24 active C-band transponders (95W TWTAs), with possible extension to 30 transponders based on available capacity and thermal emission;
- 16 active Ku-band transponders (185W TWTAs);
- 12 active multi-beam Ku-band transponders (136W TWTAs);
- 2 active Ka-band transponders (125W TWTAs);
- 1 active L-band transponder for regional coverage and 2 active L-band transponders for global coverage.
The satellite has 12 communications and relay antennas:
- two 2.6m deployable C-band reflectors;
- two C-band horns that transmit radio beacon signals and telemetry;
- two 2.2m deployable Ku-band reflectors;
- one 0.7m Ku-band reflector;
- one Ku-band horn to transmit radio beacon signals;
- two 0.6m Ka-band reflectors;
- two active L-band antenna feed arrays for regional and global coverage.
Intended to separate the adapter and the satellite in flight, the upper part is based on an 1194VX separation system designed and manufactured by RUAG Space AB (former Saab Space AB). It also includes two separation control sensors and telemetry sensors.
The lower part is an isogrid carbon fiber-reinforced plastic adapter which hosts two brackets with separation connectors, a telemetry sensor and a cable network. The outer surface of adapter system is covered with MLI to maintain the required temperatures across both the spacecraft and the separation system.
The relative velocity of the separated parts is provided by the spring pushers.