Athena II: The Next-Generation Launcher for Small Satellites
Introduction
The Athena II was an American small‑lift, expendable launch vehicle developed in the 1990s to provide reliable, low‑cost access to low Earth orbit (LEO), sun‑synchronous orbits (SSO) and even interplanetary trajectories for payloads in the ~500–2,100 kg class. Designed by Lockheed Martin with propulsion from Thiokol/ATK, Athena II combined heritage solid‑rocket stages with a hydrazine orbital adjustment module to deliver precise insertions for scientific, commercial and government customers.
Design and configuration
- Stages: Four-stage stack — two Castor 120 solid first/second stages, an Orbus 21D (third) solid stage, and a monopropellant Orbit Adjust Module (OAM) fourth stage.
- Height / diameter / mass: ~28.2 m tall, 2.36 m diameter, gross mass ≈120,700 kg.
- Propulsion: HTPB/AP solids for stages 1–3; hydrazine monopropellant (MR‑107 thrusters) on the OAM for attitude control and fine orbital insertion.
- Payload fairings / adapters: Interchangeable fairings and adapters to support a range of small satellites and secondary payloads.
- Operational concept: “Stack‑and‑shoot” rapid integration aimed at short lead times (manufacturer-stated preparation in ~30 days).
Performance and capabilities
- LEO: ~2,065 kg to a low‑altitude LEO (nominal 185 km).
- SSO: ~1,165 kg to sun‑synchronous orbits.
- GTO / deep space: Smaller payload capability; demonstrated by the Lunar Prospector mission to lunar transfer.
- Precision: The OAM allowed multiple restarts and fine delta‑v trimming for accurate orbital insertion and separation maneuvers.
Operational history and missions
- Flights: Three
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