Cygnus OA-9E (Orbital ATK-9E) is a cargo resupply mission of the Orbital ATK Cygnus spacecraft to the International Space Station under the Commercial Resupply Services (CRS) contract with NASA.

Northrop Grumman (formerly Orbital ATK) and NASA jointly developed a new space transportation system to provide commercial cargo resupply services to the International Space Station. The Cygnus cargo ship consists of two parts, a service module built in the USA based on the GEOStar platform, and a pressurized module, manufactured in France and Italy by Thales Alenia. The cargo is sent into orbit by a launcher specially developed for this purpose.

Antares has a first stage based on Energiya lateral blocks, made in Ukraine by Yuzhnoye. It was initially powered by two NK-33s, built in the 1960s for the Soviet N1 lunar launcher, before being replaced by RD-181s, derived from the RD-170s installed on Energiya and Zenit. The second stage, a Castor-30, is made in the USA, by Northrop Grumman.

CRS OA-9E was captured by RMS on 24/05/2018 at 09:26 UTC and berthed to the Nadir port of the Unity module of the International Space Station on 24/05/2018 at 12:13 UTC. Its stay on the ISS was 52 days. It was unberthed on 15/07/2018 at 10:20 UTC and released by RMS on 15/07/201 at 12:37 UTC. It deorbited on 30/07/2018 at 09:17 UTC.