 The company decided to discontinue the Antares 100 series and accelerate the introduction of a new propulsion system.The Antares system is being upgraded with newly built RD-181 first stage engines to provide greater payload performance and increased reliability.In late 2014 Orbital contracted United Launch Alliance for an Atlas V launch of Orb OA-4 in late 2015 from Cape Canaveral, FL, and with a second Atlas V launch of Cygnus in 2016.