Athena I

The Athena I is a three-stage rocket, consisting of solid first and second stages, and a monopropellant liquid-fuelled third stage. The first stage is a Castor 120, which is also used on some versions of the Taurus rocket. An Orbus 21D motor was used as the second stage on launches up to 2001. The third stage is an Orbital Adjustment Module, fuelled by hydrazine and propelled by four MR-107 engines.