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Athena II

 

 

Athena II Fact Sheet
Written and Edited by Cliff Lethbridge

Classification: Space Launch Vehicle

Length: 100 feet

Diameter: 7 feet, 9 inches

 

The Lockheed Martin Athena II is a three-stage big brother of the Athena I.

A single Thiokol Castor 120 solid rocket motor provides both first and second stage propulsion for the Athena II, with simply one of the solid rocket motors stacked above the other. Each Castor 120 solid rocket motor is 28 feet, 11 inches long by 7 feet, 9 inches wide.

Each Castor 120 solid rocket motor burns Class 1.3 Hydroxyl-terminated polybutadiene (HTPB) solid propellant and can produce a thrust of 435,000 pounds. The solid rocket motors employ a composite casing, with exhaust nozzle steering provided by blowdown cold gas-powered hydraulic thrust vector control (TVC) actuators.

The Athena II employs an Orbus 21D third stage manufactured by Pratt and Whitney Space Propulsion Operations, Chemical Systems Division. The third stage is 10 feet, 4 inches long by 7 feet, 8 inches wide and, like the Athena II lower stages, burns Class 1.3 HTPB solid fuel.

The third stage can produce 43,723 pounds of thrust. It employs a composite casing, with steering provided by a carbon phenolic nozzle using electromechanical TVC actuators.

Following separation of the third stage, an Orbit Adjust Module (OAM) is ignited. The OAM houses an attitude control system and avionics subsystem, which incorporate guidance and navigation equipment, batteries, telemetry transmitters and command destruct receivers and antennas.

A maximum load of 960 pounds of hydrazine liquid fuel powers the OAM attitude control system, which performs orbital injection corrections, roll control, velocity trim and orbit circularizing maneuvers. The OAM attitude control system is manufactured by Primex Technologies.

Located directly beneath the payload itself, the OAM eventually separates from the payload and performs a contamination and collision avoidance maneuver until its hydrazine fuel is depleted. The maneuver is intended to protect the payload from any potential damage.

The Athena II offers two sizes of payload fairings and three sizes of payload adapters which can be interchanged to accommodate a number of different sized payloads.

Utilizing what its manufacturer calls a "stack and shoot" approach to launching payloads, the Athena II can be prepared for launch in just 30 days after its first stage arrives at the launch site.

The rocket is capable of carrying a maximum 4,350-pound payload into low-Earth orbit or a maximum 3,200-pound payload into polar orbit.

It is also capable of sending small payloads into interplanetary trajectory, as was proven by the Athena II launch of the NASA Lunar Prospector on January 6, 1998. The Lunar Prospector weighed 652 pounds and successfully achieved lunar orbit.


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