Northrop Grumman completes GEM 63 motor’s second ground test

Northrop Grumman has completed the second ground test of a 63in diameter Graphite Epoxy Motor (GEM 63), which is designed for use on United Launch Alliance’s (ULA) Atlas V launch vehicle.

The GEM 63 motor is set to replace the strap-on boosters on the Atlas V rocket beginning in July.

The latest ground test in Promontory, Utah, US, comes after the first static test fire of the side-mounted rocket motor was performed in September.

GEM 63 has the capability to provide a maximum thrust of 373,000lb. A single Atlas V launch will require up to five GEM 63 motors.

Northrop Grumman propulsion systems vice-president Charlie Precourt said: “The Northrop Grumman team developed the GEM 63 motor in just three years, an impressive accomplishment for such a complex drop-in solution to an existing launch vehicle.”

The company developed the motor as part of a cooperative programme with ULA.

The test satisfies additional requirements that need to be met by the booster for certification by the US Air Force.

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ULA president and CEO Tory Bruno said: “This test is an important step in the development of these new boosters for the Atlas V launch vehicle and we thank Northrop Grumman for the continued partnership and outstanding teamwork.

“By flying key hardware first on our Atlas V rocket prior to flying it on our Vulcan Centaur rocket, it provides increased confidence for the first flight of our new rocket in 2021.”

The GEM 63 motors will be ready for their first launch on board Atlas V next year.

Northrop Grumman is also developing a 72ft-long GEM 63XL motor for use on ULA’s Vulcan Centaur rocket. The GEM 63XL motor, which is currently in the structural qualification process, is expected to be the longest single-case solid rocket motor ever built.