A United Launch Alliance (ULA) Atlas V 401 rocket launches the Cygnus spacecraft on the initial leg of its cargo resupply mission (OA-7) to the International Space Station (ISS). The Atlas V lifted off from Space Launch Complex-41 at Cape Canaveral Air Force Station at 11:11 a.m. on 18 April 2017.

Orbital ATK developed the Cygnus advanced maneuvering spacecraft to perform ISS cargo delivery missions under the Commercial Resupply Service (CRS) contract with NASA to carry crew supplies, spare equipment and scientific experiments to the International Space Station. At a total weight of approximately 7,225 kg (15,928 lb), OA-7 will include approximately 3,380 kg (7,452 lb) of internal cargo and an 83 kg (183 lb) external deployer carrying CubeSats.