The Hangar / Antares
Antares is a medium-lift expendable launch vehicle developed by Orbital Sciences (now Orbital ATK). Antares primary mission is to support cargo Cygnus spacecraft flights to the International Space Station (ISS) under the agency’s Commercial Orbital Transportation Services (COTS) and Commercial Resupply Services (CRS) contracts. The vehicle currently is launched out of the Mid-Atlantic Regional Spaceport’s (MARS) Pad-0A located at NASA’s Wallops Flight Facility in Virginia.
Originally named the Taurus II, Antares has the capability of sending payloads weighing more than 11,000 lbs (5,000 kilograms) to low-Earth orbit (LEO).
Antares conducted its inaugural test flight on April 21, 2013, using the 110 configuration of the launch vehicle. That flight, designated Antares A-ONE, launched a Cygnus Mass Simulator to an orbit of approximately 150 by 160 miles (240 kilometers by 260 kilometers) with an inclination of 51.6 degrees. Four cubesats were deployed from the mass simulator for Spaceflight Inc.
The second Antares launch was a demonstration flight under NASA’s COTS program, designated Orb-D1 and was the first time that Orbital Sciences had named one of the cargo vessels in honor of an astronaut – G. David Low. Low had worked with Orbital and he passed away from colon cancer in 2008. An Antares, in its 110 configuration, was used to propel the S.S. G. David low and its 1,543 lbs (700 kilograms) worth of cargo toward the ISS.
The first operational mission under the $1.9 billion CRS contract that Orbital had entered into with NASA took place on January 9, 2014 with the flight of the S.S. C. Gordon Fullerton. Fullerton had gone on to become an executive with Orbital Sciences before his passing on August 21, 2013. The flight utilized an upgraded Antares 120 rocket with an Alliant Techsystems (ATK) Castor 30B upper stage.
On January 13, 2014, Orbital Sciences carried out the second operational flight of the Antares rocket under the Orb-2 mission. The Orb-2 Antares rocket successfully delivered the Cygnus spacecraft and its 3,668 lbs (1,664 kilograms) worth of cargo, crew supplies and experiments to the International Space Station.
2014 In-Flight Anomaly
The Orb-3 mission launched on October 28, 2014 (CRS Orb-3) ended in an explosion that resulted in the loss of the rocket, the S.S. Deke Slayton Cygnus spacecraft and its cargo. The failure stemmed from a failed turbopump on one of the two Aerojet Rocketdyne-provided AJ26 engines used in Antares’ first stage. These engines were built in the 1960s, for use on the Soviet Union’s massive N-1 Moon rocket. Known as the NK-33, these engines were purchased by Aerojet Rocketdyne and renamed the AJ-26. Aerojet Rocketdyne made some modifications, including the removal of wiring, the addition of some electronics, modifying the NK-33 to use U.S. fuels and changes to the engines’ steering system. The AJ-26 encountered two failures on the test stand at NASA’s Stennis Space Center prior to the Orb-3 accident. On December 17, 2014, Orbital announced it would use the NPO Energomash RD-181 on the second-generation Antares rockets and had signed an agreement for up to 60 RD-181 engines. in late 2015, it was announced Aerojet Rocketdyne would pay Orbital ATK (the company had merged with ATK by that time) $50 million and buy back 10 AJ26s.
On October 17, 2016, the new Antares 230 rocket with two RD-181 rocket engines in its first stage, returned the Antares family of launch vehicles to service. These engines are described as providing approximately 440 kilonewtons (100,000 lbf) more thrust than the dual AJ26 engines used on the Antares 100. The Cygnus that was launched atop this rocket, the S.S. Alan Poindexter, carried 10,740 lbs (4,870 kilograms) of cargo to the ISS.
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
|First Stage||Second Stage||Third Stage|
|1 – Two AJ26 engines
|2 – CASTOR 30B||0 – None|
|2 – Two RD-181 engines||3 – CASTOR 30XL||1 – Bi-Propellant
|3 – Star 48-based
Antares has a number of configurations designated by the propulsion systems that it utilizes. Whereas the 100 series flew using the Aerojet Rocketdyne AJ26 engine in its first stage, the 200 series uses the RD-181. These engines utilize a mixture of RP-1 (a highly-refined form of kerosene) and liquid oxygen (LOX).
Meanwhile Antares’ second stage uses either Orbital ATK’s Castor 30B or Castor 30XL solid rocket motors. While Antares flies without a third stage when launching Cygnus to the International Space Station. However, the Antares launch system does offer an optional third stage using either an Orbital ATK Bi-Propellant Third Stage or a Star 48-based third stage.
Antares Payload Upmass
The 230 variant of the rocket is rated to launch up to 15,400 lbs (7,000 kilograms) to LEO or up to 7,700 lbs (3,500 kilograms) aboard Cygnus to the ISS. The 231 variant is designed to launch up to 6,614 lbs (3,000 kilograms) to Sun-synchronous orbit (SSO). The 232 variant will launch up to 5,600 lbs (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.
To date, Antares has flown only payloads pertaining to the Commercial Resupply Services contract. However, Orbital ATK’s literature on the vehicle includes payload data for a wide array of orbits and therefore Antares can be used to send an array of payloads for various customers.
|Launch sites||Mid-Atlantic Regional Spaceport Pad 0A|
|First Flight||Antares A-ONE
April 21, 2013
|Notable payloads||CRS Orb-3
* Data current as of February 2017
- June 15, 2017: Orbital ATK OA-8E Cygnus cargo mission slated for late summer
- October 30, 2016: Reflections on the launch of OA-5: Remembering
- October 25, 2016: Reflections on the launch of OA-5: Waiting
- October 24, 2016: Reflections on the launch of OA-5: Infinite Blue
- October 23, 2016: Photo Gallery: Light, shadow and fog – the flight of OA-5
- October 22, 2016: SFI Video: Launch of Antares 230 with S.S. Alan Poindexter Cygnus spacecraft
- October 18, 2016: Antares lights up Virginian night skies in return-to-flight OA-5 mission
- October 16, 2016: Antares launch postponed 24 hours
- October 15, 2016: Flame experiments among cargo being sent to ISS with OA-5 Cygnus
- October 15, 2016: With little damage to tracking station, OA-5 set to launch Sunday
Antares graphics and photos provided by SpaceFlight Insider.