The A2100 is a model of communications satellite spacecraft made by Lockheed Martin Space Systems. It is used as the foundation for telecommunications payloads in geosynchronous orbit, as well as GOES-R weather satellites and GPS Block IIIA satellites. Over 40 satellites use the A2100 bus.^[1][2]

The first satellite, AMC-1, was launched September 8, 1996, and has achieved 15-year on-orbit service life.^[3][4] Since 1996 there have been over 45 of the A2100 based satellites launched, with over 400 years of total on-orbit service.^[5] Other A2100 spacecraft include JCSAT-13 and VINASAT-2, which were launched May, 2012 on an Ariane 5 rocket,^[6] as well as Arabsat-6A and Hellas Sat 4/SaudiGeoSat-1 of Saudi Arabia's Arabsat-6G program.^[7]

In 2002, Lockheed Martin Commercial Space Systems was given a Frost and Sullivan Satellite Reliability Award for excellence in the production of flexible and reliable communications satellites used in geosynchronous Earth orbit.^[8]

A2100 customers includes communications companies around the world, including Astra, Telesat, SKY Perfect JSAT Group and others.

The Lockheed Martin A2100 geosynchronous spacecraft series is designed for a variety of telecommunications needs including K_a band broadband and broadcast services, fixed satellite services in C-band and K_u band payload configurations, high-power direct broadcast services using the K_u band frequency spectrum, and mobile satellite services using UHF, L-band and S-band payloads.^[9]

The A2100 satellite system was developed by the Astro Space team at its East Windsor, New Jersey facility, with team members delivering a flexible common bus with fewer components, lower spacecraft weight, and reduced customer delivery time.^[10]

The A2100 is being supplanted by the LM2100, an evolutionary upgrade with several new features. The military version is the LM2100 Combat Bus.^[11][12]

The attitude control system includes reaction wheels,^[13] with momentum desaturation and main motor maneuver attitude control propulsion provided by small monopropellant hydrazine motors. This hydrazine supply is contained in a central propellant tank of 0.90 m diameter and up to 2.00 m length depending on the customer's requirements.^[14] This tank's maximum length was later increased to 2.55 m.^[15] The liquid apogee engine uses hydrazine fuel from the central tank along with nitrogen tetroxide oxidizer from two flanking tanks of 0.54 m diameter and up to 1.65 m long.^[16] Orbit maintenance is performed by the small hydrazine motors and ion thrusters.^[17] The maximum propellant supply (with the largest tanks at 95% fill factor) are 1368 kg of hydrazine fuel and 627 kg of nitrogen tetroxide oxidizer.

According to Moog-ISP, the A2100 platform uses its LEROS bipropellant Liquid Apogee Engine.^[18]