RCSP ESPA

As the program lead for ESPA here at Moog CSA since 1998, it’s exciting to see the developing RCSP mission scenario utilizing the ESPA Ring. We originally developed ESPA (the EELV Secondary Payload Adapter) for the Air Force to benefit the small satellite community. ESPA functioned in a slightly different role when it enabled the NASA LCROSS mission to share the launch vehicle with the Lunar Reconnaissance Orbiter (LRO). There are numerous ESPA missions currently in planning, and the Rocket City Space Pioneers’ approach to flying our Lander to the moon is one of the most innovative uses to date. ESPA started as one particular design and now it’s grown into a family of multi-payload adapters.

Here’s some background on the ESPA Ring… Moog CSA developed the ESPA under a Small Business Innovative Research contract from the Space Vehicles Directorate of the Air Force Research Laboratory (AFRL/RV). The program was a joint effort between the AFRL, the DoD Space Test Program, and CSA to develop a secondary payload capability for the Evolved Expendable Launch Vehicles (EELVs). The original ESPA Ring is qualified to mount a 20,000-lb primary satellite and six 400-lb secondary satellites on a Delta IV or Atlas V vehicle, but it isn’t just for EELV; ESPA is compatible with the Falcon 9 and Taurus 2 Vehicles and we also make variants called Small Launch ESPA.

ESPA is installed between the launch vehicle upper stage and the primary spacecraft. To provide minimal impact to the primary spacecraft, the ESPA duplicates the standard interface plane of the EELV upper stage and is designed to be very stiff in all directions. Since the standard ESPA ring is 24 inches high, only a small amount of volume is taken away from the primary. The image below (from the Air Force Art Collection!) illustrates the integration of the STP-1 mission around the ESPA in early 2007. On March 8, 2007, the ESPA Ring debuted on the launch of STP-1 on an Atlas V from Cape Canaveral; this Mission placed in orbit six unique spacecraft.

ESPA Ring flight unit

Launch stack for maiden flight

In June, 2009, NASA launched the Lunar CRater Observation and Sensing Satellite (LCROSS) as a secondary mission on the LRO Atlas V. The objective of LCROSS was to look for water ice at the lunar polar regions. LCROSS consisted of a lunar impactor and a “shepherding” spacecraft; the impactor was the upper stage of the rocket, and the spacecraft was built around an ESPA Ring. About 3 months after launch, the upper stage impacted a target crater on the lunar south pole, creating a plume over 50 km high. The ESPA-based spacecraft, built by Northrop Grumman, guided the impactor into the crater, and followed through the plume making on-the-fly measurements and assessments. The ESPA spacecraft followed with its own impact of the lunar surface, approximately 4 minutes later. The LCROSS mission was a huge success, and the plume from the impact helped LRO confirm the presence of ice.

ESPA as hub of LCROSS Shepherding Satellite, impacting the lunar surface, October 2009

The AFRL DSX (Demonstration and Science Experiments) Program has based its free-flyer spacecraft configuration on the ESPA Ring. DSX ESPA is a four-port Ring that will be the hub of the free-flyer DSX spacecraft in Medium Earth Orbit.

There are several variations on ESPA that are being considered to enable a variety of mission scenarios. Propulsive ESPA Rings, as demonstrated by LCROSS, are in development as orbital maneuvering vehicles.

The RCSP team is building our mission around two Rings, including one with propulsion. The first Ring will be deployed with secondary satellites into Geosynchronous Transfer Orbit (GTO); the second Ring will propel itself into Low Lunar Orbit (LLO) for deployment of our lunar lander along with two other lunar spacecraft.

RCSP notional payload stack