NASA awarded Orbital a Commercial Orbital Transportation Services (COTS) Space Act Agreement (SAA) in 2008 to demonstrate delivery of cargo to the International Space Station. Orbital (and later Northrop Grumman) used Antares to launch its Cygnus spacecraft for these missions. As of August 2023[update] it has only been used for Cygnus launches to the ISS, despite it being intended for commercial launches. Originally designated the Taurus II, Orbital Sciences renamed the vehicle Antares, after the star of the same name,[13] on December 12, 2011.
Out of 18 total launches, Antares has suffered one failure. During the fifth launch on October 28, 2014, the rocket failed catastrophically, and the vehicle and payload were destroyed.[14] The rocket's first-stage engines were identified as the cause for the failure. A different engine was chosen for subsequent launches, and the rocket had a successful return to flight on October 17, 2016.
The Antares has flown two major design iterations, the 100 series and 200 series. Both series have used a Castor 30XL as an upper stage but have differed on the first stage.[15] The 100 series used two Kerolox powered AJ26 engines in the first stage and launched successfully four times. The 100 series was retired following a launch failure in 2014.[16] The 200 series which first flew in 2016 also featured a Kerolox first stage but instead used two RD-181 engines along with other minor upgrades. The 200 series future became uncertain following the Russian invasion of Ukraine. Due to the first stage being produced in Ukraine and the engines in Russia, future production of the rocket was unable to be continued.[15] As a result Northrop Grumman entered into an agreement with Firefly Aerospace to build the first stage of the Antares 300 series. Northrop also contracted with SpaceX for 3 Falcon 9 launches.[17]
Orbital Sciences COTS demonstration flight. First Antares mission with a real Cygnus capsule, first mission to rendezvous and berth with the International Space Station, second launch of Antares. The rendezvous maneuver was delayed due to a computer data link problem,[21] but the issue was resolved and berthing followed shortly thereafter.[22][23]
LOX turbopump failure T+6 seconds. Rocket fell back onto the pad and exploded.[32][33][34] First Antares launch to use Castor 30XL upper stage. In addition to ISS supplies, payload included a Planetary ResourcesArkyd-3 satellite[35] and a NASA JPL/UT Austin CubeSat mission named RACE.[36]
Spacecraft carried ISS hardware, crew supplies, and scientific payloads, including the Cold Atom Lab and the Biomolecule Extraction and Sequencing Technology experiment.[46] The Cygnus also demonstrated boosting the station's orbital velocity for the first time, by 0.06 meter per second.[47]
Largest number of satellites launched on a single rocket (108). Cygnus NG-10, CHEFsat 2, Kicksat 2, 104 Sprite Chipsats (deployed from Kicksat 2), MYSAT 1.
Cygnus NG-12 is the first mission under the NASA Commercial Resupply Services-2 contract. NG-12 is also the first to use upgraded launcher, Antares 230+.
Spacecraft carried ISS hardware, crew supplies, and scientific payloads, including a new toilet (Universal Waste Management System, UWMS), Ammonia Electrooxidation, radishes for Plant Habitat-02, drugs for targeted cancer treatments with Onco-Selectors, and a customized 360-degree camera to capture future spacewalks.[51][50]
This mission carried over 8,000 pounds of cargo including roundworms to study muscle loss and the Spaceborne Computer 2, as well as an experiment to study the protein-based manufacturing of artificial retinas.[53]
Note: Cygnus CRS OA-4, the first Enhanced Cygnus mission, and Cygnus OA-6 were propelled by Atlas V 401 launch vehicles while the new Antares 230 was in its final stages of development. Cygnus CRS OA-7 was also switched to an Atlas V 401 and launched on April 18, 2017