This is the 2nd mission under NASA's Commercial Resupply Service agreement with Orbital Sciences The unmanned Cygnus cargo vessel delivered approximately 1494kg of supplies and science experiments to the International Space Station.

Antares known during early development as Taurus II, is an expendable launch system developed by Orbital Sciences Corporation (now part of Northrop Grumman Innovation Systems after Northrop Grumman acquired Orbital ATK) and the Yuzhnoye 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 5,000 kg (11,000 lb) into low-Earth orbit, Antares is the largest rocket operated by Orbital ATK. Antares launches from the Mid-Atlantic Regional Spaceport and made its inaugural flight on April 21, 2013.

• Commercial Resupply Services

  Human Spaceflight
  Commercial Resupply Services (CRS) are a series of flights awarded by NASA for the delivery of cargo and supplies to the International Space Station.The first CRS contracts were signed in 2008 and awarded $1.6 billion to SpaceX for twelve cargo Dragon and $1.9 billion to Orbital Sciences for eight Cygnus flights, covering deliveries to 2016. The Falcon 9 and Antares rockets were also developed under the CRS program to deliver cargo spacecraft to the ISS.
  Program wiki
• International Space Station

  Human Spaceflight
  The International Space Station programme is tied together by a complex set of legal, political and financial agreements between the sixteen nations involved in the project, governing ownership of the various components, rights to crewing and utilization, and responsibilities for crew rotation and resupply of the International Space Station. It was conceived in 1984 by President Ronald Reagan, during the Space Station Freedom project as it was originally called.
  Program infoProgram wiki