The GEM 63XL motor static test firing. Credit: Northrop Grumman

WASHINGTON — Northrop Grumman on Aug. 13 completed the first qualification test of a new strap-on rocket motor developed for United Launch Alliance’s future vehicle Vulcan Centaur, the company said.

The static firing of the 63-inch-diameter graphite epoxy motor known as GEM 63XL took place at Northrop Grumman’s facility in Promontory, Utah.

During the test the motor fired for approximately 90 seconds, producing nearly 449,000 pounds of thrust to qualify the motor’s internal insulation, propellant grain, ballistics and nozzle, Charlie Precourt, Northrop Grumman vice president of propulsion systems, said in a news release.

Northrop Grumman last month delivered to ULA three GEM 63 solid rocket motors that will fly later this year on an Atlas 5 vehicle.

The GEM 63 is 66-feet long and the GEM 63XL version is 72-feet long. The GEM 63XL motors will fly on the Vulcan Centaur rocket in 2021.

The GEM strap-on motors were first developed in the early 1980s. The GEM 40 was used in ULA’s Delta 2 launch vehicle. The GEM 46 flew on the Delta 2 Heavy, and the GEM 60 flew on Delta 4 launches before it was retired in 2019.

Sandra Erwin writes about military space programs, policy, technology and the industry that supports this sector. She has covered the military, the Pentagon, Congress and the defense industry for nearly two decades as editor of NDIA’s National Defense...