A Northrop Grumman Antares rocket launched the 20th Cygnus cargo freighter on the 19th operational cargo delivery flight to the International Space Station. The mission is known as NG-19. The rocket flew in the Antares 230+ configuration, with two RD-181 first stage engines and a Castor 30XL second stage. This was the final flight of an Antares 230+ rocket before a redesign with new U.S.-made engines. Delayed from March, April 21, May, and July.