Antares, known during early development as Taurus II, is an expendable launch system developed by Orbital Sciences Corporation and the Pivdenne Design Bureau to launch the Cygnus spacecraft to the International Space Station as part of NASA's COTS and CRS programs. Able to launch payloads heavier than 8,000 kg (18,000 lb) into low Earth orbit, Antares is the largest rocket operated by Northrop Grumman. Antares launches from the Mid-Atlantic Regional Spaceport and made its inaugural flight on April 21, 2013. Antares 100 was retired in 2014 and series 200 was retired in 2023 due to component unavailability. As of January 2024 Antares 300 is under development.

Orbital Sciences Corporation was an American company specializing in the design, manufacture, and launch of small- and medium- class space and launch vehicle systems for commercial, military and other government customers. In 2014, Orbital merged with Alliant Techsystems to create a new company called Orbital ATK, Inc., which in turn was purchased by Northrop Grumman in 2018. The remnants of the former Orbital Sciences Corporation became a subsidiary of Northrop Grumman, known as Northrop Grumman Space Systems.