Antares is a medium-lift expendable launch vehicle developed by Orbital Sciences (now Orbital ATK). Antares primary mission is to support cargo Cygnus spacecraft launches to the International Space Station (ISS) under the Commercial Resupply Services (CRS) contract. The vehicle launches from the Mid-Atlantic Regional Spaceport at NASA’s Wallops Flight Facility in Virginia.

After its inaugural test flight in 2013, Antares flew three cargo missions to the ISS before suffering a catastrophic launch failure on its fifth flight on October 28, 2014 (CRS Orb-3). The launch failure stemmed from a failed turbopump on one of its AJ26 engines, and led to the selection of the RD-181 as a replacement engine. This upgraded version of Antares, dubbed the 200-series, debuted on October 17, 2016.

Mission Profile

To date, Antares has launched exclusively to the ISS from Wallops Flight Facility. Orbital ATK advertises that the vehicle is compatible with facilities at Vandenberg Air Force Base in California, Cape Canaveral Air Force Station in Florida, and Kodiak Launch Complex in Alaska.

Upon liftoff, the twin RD-181 engines provide thrust vector control to perform pitch and yaw maneuvers. The first stage burns for 215 seconds before main engine cutoff and stage jettison. Following first stage jettison, there is a pause of approximately one minute, after which the interstage surrounding the upper stage motor nozzle separates and the second stage motor ignites. The payload fairing jettisons after second stage ignition. The second stage burns for 156 seconds before burning out, after which the payload separates and coasts to the International Space Station.

Configurations and Performance

Exploded view of an Antares 200 with the Cygnus spacecraft. Image Credit: Orbital ATK

Antares has a number of configurations designated by the propulsion systems in use. Whereas the 100 series flew the Aerojet Rocketdyne AJ26 engine (a refurbished Russian NK-33) in its first stage, the 200 series uses two Russian-built NPO Energomash kerosene/liquid oxygen RD-181 engines.

The second stage uses Orbital ATK’s Castor 30B or Castor 30XL solid rocket motor. While Antares flies without a third stage when launching Cygnus to the ISS, the system also offers an optional third stage using an Orbital ATK Bi-Propellant Third Stage or a Star 48-based third stage.

The 230 variant of the rocket is rated to launch up to 7,000 kg to low-Earth orbit (LEO) or up to 3,500 kg aboard Cygnus to the ISS. The 231 variant will launch up to 3,000 kg to Sun-synchronous orbit (SSO). The 232 variant will launch up to 2,700 kg to geosynchronous equatorial orbit (GEO).

The Antares first stage is designed and built by the Ukrainian company Yuzhnoye and is based on the Zenit rocket, with overall vehicle integration being performed by Orbital ATK. The stage produces 3,265 kN of thrust, burning for 215 seconds. The Castor 30XL second stage SRM produces 293.4 kN of thrust and burns for 156 seconds.

Vehicle Status

Orbital ATK is currently launching Cygnus cargo vehicles to the ISS aboard United Launch Alliance’s Atlas V launch vehicle. As noted previously, the Antares launch failure stemmed from a failed turbopump on one of its AJ26 engines. An investigation resulted in an enhanced version of Antares, which returned to flight with the OA-5 mission to the ISS in October 2016.

Payloads

To date, Antares has flown only payloads related to the Commercial Resupply Services contract. However, Orbital ATK’s literature on the vehicle includes payload data for a wide array of orbits.

• August 2, 2023: Final Antares 230+ rocket launches NG-19 Cygnus spacecraft
• July 31, 2023: Northrop Grumman prepares the final Antares 230+ rocket
• November 7, 2022: Penultimate Antares 230+ rocket lofts Cygnus spacecraft to ISS
• November 5, 2022: NG-18 Cygnus cargo ship to launch new science to ISS
• August 8, 2022: Antares rocket to see new life with upgraded ‘330’ variant
• February 19, 2022: NG-17 Cygnus lofted into orbit, beginning 40-hour ISS chase
• February 18, 2022: NG-17 Cygnus sending new science to International Space Station
• February 20, 2021: Northrop Grumman on track for launch of NG-15
• February 18, 2021: NG-15 Cygnus set to send new experiments to the space station
• October 2, 2020: Northrop Grumman successfully launches NG-14 Cygnus spacecraft