Three Northrop Grumman Graphite Epoxy Motors (GEM) 63 were used for the first time on 13 November in launching a United Launch Alliance (ULA) ATLAS V rocket carrying US National Reconnaissance mission 101 (NROL-101).

Some 63in in diameter and 66ft long, the GEM 63s each produce 371,550lbs of thrust to augment the 860,200lbs of the RD AMROSS RD-180 main engine. The RL10C-1 engine for the CENTAUR upper stage was provided by Aerojet Rocketdyne. The launch was the 86th for the ATLAS V.

The GEM 63 rocket motors were developed to enhance the performance of the existing Atlas V launch vehicle while incorporating our flight-proven, heritage designs that provide a significantly lower cost for boost propulsion,” said Charlie Precourt, VP, Propulsion Systems at Northrop Grumman.

Northrop Grumman began supplying rocket propulsion to ULA in 1964, and the GEM family of strap-on motors appeared in the 1980s. Since then, 1,152 GEM motors have supported 165 launches on DELTA II, DELTA II Heavy and DELTA IV launch vehicles. The family has recently expanded with the development of the GEM 63XL variant to support ULA’s VULCAN CENTAUR. The GEM 63 was developed under a cooperative agreement with ULA.

Developed in cooperation with ULA, each GEM 63 delivers 371,550lbs of thrust: up to five can be used on a single ATLAS V rocket. (Photos: Northrop Grumman)

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