|Country of origin||USA|
|Used on||Atlas V|
|Height||17.0 m (669 in)|
|Diameter||1.6 m (62 in)|
|Gross mass||46,697 kg (102,949 lb)|
|Thrust||1,688.4 kN (379,600 lbf)|
|Burn time||94 seconds|
The AJ-60A rocket motor was developed between 1999 and 2003 for use on the Atlas V.
On January 19, 2006 the New Horizons spacecraft to Pluto was launched directly into a solar-escape trajectory at 16.26 kilometers per second (58,536 km/h; 36,373 mph) from Cape Canaveral using an Atlas V version with 5 of these SRBs and Star 48B third stage. New Horizons passed the Moon's orbit in just nine hours.
In 2015, ULA announced that the Atlas V will switch to new GEM 63 boosters produced by Northrop Grumman Innovation Systems. (GEM 63XL, a stretched version of the GEM 63 booster will be used on the upcoming Vulcan rocket.) The first Atlas V launched with GEM 63 boosters on November 13, 2020.
AJ-60A is a solid fueled rocket burning HTPB. The casing is composed of a graphite epoxy composite, and the engine throat and nozzle are made of carbon-phenolic composite. As configured for use on Atlas V, the nozzle is fixed at a 3 degree cant away from the attachment point, but Aerojet offers a variant with thrust vectoring capability. The Atlas V configuration also features an inward slanting nosecone, but it is available with a conventional nosecone or none at all for use on other rockets. The stages are designed to be transported by truck.