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AJ-60A is a solid rocket booster produced by Aerojet Rocketdyne. They are currently used as strap-on boosters on United Launch Alliance's Atlas V rocket.

Atlas V SRB without Nose cone.jpg
An AJ-60A booster, without nosecone attached, being fitted to an Atlas V
ManufacturerAerojet Rocketdyne
Country of originUSA
Used onAtlas V
General characteristics
Height17.0 m (669 in)
Diameter1.6 m (62 in)
Gross mass46,697 kg (102,949 lb)
Engine details
Thrust1,688.4 kN (379,600 lbf)
Burn time94 seconds


The AJ-60A rocket motor was developed between 1999 and 2003 for use on the Atlas V.[1] In 2015, ULA announced that the Atlas V will switch to new GEM 63 boosters produced by Northrop Grumman Innovation Systems. A stretched version of this booster will be used on the upcoming Vulcan rocket.[2]

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 the these SRBs and Star 48B thirdstage .[3] New Horizons passed the Moon's orbit in just nine hours.[4][5]


AJ-60A is a solid fueled rocket burning HTPB.[6] 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.[1] 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. AJ-60A is the largest monolithic solid rocket motor currently in production. The stages are designed to be transported by truck.[6]


  1. ^ a b "Atlas V Solid Rocket Booster". Archived from the original on March 14, 2017. Retrieved January 6, 2016.
  2. ^ Jason Rhian (23 September 2015). "ULA selects Orbital ATK's GEM 63/63 XL SRBs for Atlas V and Vulcan boosters". Spaceflight Insider.
  3. ^ Scharf, Caleb A. (February 25, 2013). "The Fastest Spacecraft Ever?". Scientific American. Retrieved July 12, 2017.
  4. ^ Neufeld, Michael (July 10, 2015). "First Mission to Pluto: The Difficult Birth of New Horizons". Smithsonian. Retrieved April 21, 2018.
  5. ^ "New Horizons: Mission Overview" (PDF). International Launch Services. January 2006. Archived from the original (PDF) on September 9, 2016. Retrieved April 21, 2018.
  6. ^ a b "Atlas V User's Guide 2010" (PDF). 2010. Retrieved January 6, 2016.