Photos: Atlas 5 on the pad awaiting liftoff on NROL-52

United Launch Alliance has selected Orbital ATK to provide solid rocket boosters for the company’s next-generation Vulcan launcher, and will switch the workhorse Atlas 5 to the new booster supplier by the end of 2018, officials said Tuesday.

The Pentagon has awarded at least $162 million in contracts to Aerojet Rocketdyne and United Launch Alliance for development of the AR1 and BE-4 rocket engines, candidates to power the first stage of a next-generation rocket and replace the Russian-made engine currently flying on the Atlas 5 launcher.

For its 70th launch in 14 years, the Atlas 5 rocket carried the NROL-79 payload into space for the National Reconnaissance Office.