The STAR-2 Bus is a fully redundant, flight-proven, spacecraft bus designed for geosynchronous missions.
It is a satellite platform manufactured by Orbital Sciences Corporation with an apogee kick motor to place a communications satellite into geostationary orbit, a thruster to provide the satellite with orbital station-keeping for a 15-year mission, and solar arrays to provide the satellite payload with 5 kW of electrical power.
Orbital's GEOStar-2 Bus design is unique within the satellite industry. Orbital’s GEOStar-2 Bus provides an affordable low-to-medium power satellite platform that is ideal for missions of this size. Rather than being a less efficient version of a larger, heavier product, Orbital’s GEOStar-2 Bus is designed specifically for the 1,000 to 5,550 watts payload class. The GEOStar-2 Bus is flight-proven with excellent operational performance among the 29 currently in-orbit. With two more GEOStar-2 satellites now in production or awaiting launch, Orbital has established its class of GEO satellite products as the unquestioned market leader.
The GEOStar-2 Bus satellite is a modular, mass efficient structure, designed for simplified integration to reduce manufacturing cycle times. The structure is supported by a composite thrust cylinder, to which the bus, payload, nadir and base panels are connected. Energy from two multi-panel solar wings and lithium ion batteries is electronically processed to provide 36 volts regulated power to the satellite throughout the mission. All active units aboard the satellite are connected through a 1553 data bus. Commands and telemetry are processed through the flight software resident on the flight processor, which provides robust autonomous control to all GEOStar-2 satellites. The modularity of the structure and the standard 1553 interfaces allow parallel assembly and test of the bus and payload systems, reducing manufacturing schedule risk by minimizing the time spent in serial satellite integration and test flow.
While primary applications are Fixed Satellite Services (FSS) and Broadcast Satellite Services (BSS), the GEOStar-2 Bus can be adapted for MSS, Earth and space science applications, as well as for technology demonstration or risk reduction programs. Depending on mission duration requirements, the GEOStar-2 Bus can accommodate payloads in excess of 500 kilograms, and provide up to 5,550 watts of power. Instrument data can be provided in standard format such as CCSDS or through secured encryption, as approved by the National Security Agency (NSA).