ESPA: The EELV Secondary Payload Adapter

Heavy lift. Excess capacity.  And now a way to use it.

The ESPA ring, or the Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter was developed to utilize excess launch capacity by mounting additional payloads below the primary spacecraft.  This reduces launch costs for the primary mission and enables secondary and even tertiary missions with minimal impact to the original mission.

ESPA allows up to six secondary satellites, up to 400 pounds each, to "share a ride to space" on Delta IV or Atlas V launch vehicles while carrying a large primary satellite.  ESPA can accommodate up to a 15,000-pound primary satellite using the standard EELV interface plane bolt pattern, which is a drop-in component in the launch stack.  The standard secondary interface is a 15-inch-diameter bolt circle with 24 fasteners.

The ESPA structure underwent extensive engineering analysis and a qualification test program to demonstrate its capability to withstand the harsh launch vibration environment.  Moog CSA can provide the mechanical design, stress analysis and structural test engineering to tailor ESPA for each customer's needs.

ESPA was developed by CSA Engineering, under an SBIR contract to the Air Force Research Laboratory Space Vehicles Directorate (AFRL/VS) for the DoD Space Test Program (SMC/Det 12).  STP developed technology requirements and operational inputs.  AFRL/VS led the research and development effort and integrated the technology development team.