Athena
Performance
The performance capability shown includes both the spacecraft and payload adapter. The mass of the adapter and any other mission-unique payload support equipment must be subtracted to determine the performance available for the spacecraft. Typical adapter masses are 50–75 kg (110–165 lbm). Athena can reach inclinations from 28.5 deg to roughly 50 deg launching from Cape Canaveral AFS, or roughly 64 deg to 115 deg launching from Kodiak, Alaska. In a typical launch profile, the two or three solid stages fire in sequence to reach near-orbital velocity. The small, liquid-fueled OAM provides orbit circularization, velocity trim, and precision orbit injection. For missions to high-altitude LEO orbits, the OAM performs an initial burn for injection into an elliptical transfer orbit, and then performs a separate circularization burn at apogee. The OAM flight performance reserve ensures that Athena can meet the required injection requirements with 99.7% probability of sufficient performance. The restartable OAM can also deploy multiple payloads and can deorbit after payload separation to reduce orbital debris.
Lockheed Martin will replace the current Orbus® 21D solid motor with the lighter weight Orbus 21G beginning with the ninth vehicle. The performance shown assumes the use of the Orbus 21G. Performance of older vehicles is roughly 50–75 kg (110–165 lbm) lower. For high-energy missions, such as GTO or Earth escape trajectories, a small solid kick stage based on the Thiokol Star 37FM motor can be attached to the spacecraft. This stage was first used to send Lunar Prospector to the moon in 1998.
(Performance graphs)
Altitude (km)
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Payload (kg)
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GEO Altitude
Athena II: Earth Escape Capability