Spacecraft Payload Interfaces

The Moog ESPA Ring and other payload adapters support multiple satellites of different sizes on EELV class (Atlas V, Delta IV, and Falcon 9), Minotaur Family, Pegasus, Athena, Antares, and other vehicles. Moog adapters can be used for Small Satellites including ESPA-Class payloads down to Nanosatellites (CubeSats) in addition being a spacecraft structure.

EELV Secondary Payload Adapter (ESPA) Ring

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 EELV class launch vehicles (Atlas V, Delta IV, Falcon 9) while carrying a large primary satellite. ESPA can accommodate up to a 15,000-pound primary satellite using the standard 62-inch 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.

ESPA Grande allows up to four secondary satellites, up to 660 pounds each, while maintaining the same interface and capacity of the standard ESPA. The standard secondary interface is a 24-inch diameter bolt circle. The ESPA Grande has been used as the primary payload for constellation deployment.

Small Launch ESPA is designed for a 38-inch diameter launch vehicle interface with either 8-inch or 15‑inch diameter bolt circles.

The ESPA structure underwent extensive engineering analysis and a qualification test program to demonstrate its capability to withstand the harsh launch vibration environment. Moog can provide the mechanical design, stress analysis and structural test engineering to tailor ESPA for each customer's needs including modifying the number and size of interface ports, adding mounting pads, and modify height.

ESPA can be used as secondary payload adapter, constellation deployment adapter, satellite structural bus, or platform for a free-flyer.


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CASPAR, the Composite Adapter for Shared Payload Rides, is a Multi-Payload Adapter (MPA) developed by Moog with whole-spacecraft vibration isolation for the Minotaur IV Launch Vehicle. CASPAR accommodates two 1500-lb satellites, or up to four ESPA-class satellites when used with one or two Flat-Plate Adapters (FPAs).

Flat-Plate Adapter (FPA)

Flat-Plate Adapter, or FPA, supported NASA's GRAIL mission and the Delta II launch. FPA is compatible with ESPA or CASPAR, and it mounts two ESPA-class satellites side by side. FPA is available with Moog’s SoftRide isolation and it can be scaled up or down for larger or smaller spacecraft. FPA's can be used to adapter spacecraft to standard interfaces.

Missions: GRAIL, ORBCOMM Generation 2 (OG2)


ESPA SUM, the ESPA 6U Mount, mounts a pair of 3U CubeSats or a single 6U CubeSat on an ESPA port. The CubeSats are tertiary payloads that share the port with a secondary satellite and deploy after secondary separation. One 6U or two 3Us can be deployed from each port. Up to six SUMs can be included on an ESPA Mission. Moog can provide a variety of CubeSat dispenser hardware and integration services which are fully compatible with our ESPA ring.