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he first stage uses RP-1 (kerosene) and liquid oxygen (LOX) as propellants, powering two Aerojet AJ-26 engines, which are modified Soviet-built NK-33 engines. Together they produce 3,265 kilonewtons (734,000 lbf) of thrust at sea level and 3,630 kN (816,100 lbf) in vacuum.[6] As Orbital has little experience with large liquid stages and LOX propellant, some of the Antares first stage work was contracted to the Ukrainian Yuzhnoye SDO, designers of the Zenit series.[11] The core provided by Yuzhnoye includes propellant tanks, pressurization tanks, valves, sensors, feed lines, tubing, wiring and other associated hardware.[19]
Like Zenit, the Antares vehicle has a diameter of 3.9 m (150 in) with a matching 3.9 m payload fairing.[2] The fairing is manufactured by Applied Aerospace Structures Corporation of Stockton, California, which also builds other composite structures for the vehicle, including the fairing adaptor, stage 2 motor adaptor, stage 2 interstage, payload adaptor, and avionics cylinder.[20]
The second stage is a solid-fuel rocket, the Castor 30. Developed by ATK as a derivative of the Castor 120 solid stage, the Castor 30B produces 293.4 kN (65,960 lbf) average and 395.7 kN (88,960 lbf) maximum thrust, and uses electromechanical thrust vector control.[6] Antares' Castor 30 solid stage was based on the Castor 120 solid motor used as Minotaur-C's first stage.[21] The first two flights of Antares used a Castor 30A, followed by two flights of the Antares 120 using an enhanced Castor 30B. The longer Castor 30XL second stage will be used on subsequent ISS resupply flights, allowing Antares to carry larger Enhanced Cygnus.[6][22][23]
Orbital Sciences offers two optional third stages, the Bi-Propellant Third Stage (BTS) and an ATK Star 48-based third stage. BTS is derived from Orbital Sciences' GEOStar spacecraft bus and uses nitrogen tetroxide and hydrazine for propellant; it is intended to precisely place payloads into their final orbits.[2] The Star
Like Zenit, the Antares vehicle has a diameter of 3.9 m (150 in) with a matching 3.9 m payload fairing.[2] The fairing is manufactured by Applied Aerospace Structures Corporation of Stockton, California, which also builds other composite structures for the vehicle, including the fairing adaptor, stage 2 motor adaptor, stage 2 interstage, payload adaptor, and avionics cylinder.[20]
The second stage is a solid-fuel rocket, the Castor 30. Developed by ATK as a derivative of the Castor 120 solid stage, the Castor 30B produces 293.4 kN (65,960 lbf) average and 395.7 kN (88,960 lbf) maximum thrust, and uses electromechanical thrust vector control.[6] Antares' Castor 30 solid stage was based on the Castor 120 solid motor used as Minotaur-C's first stage.[21] The first two flights of Antares used a Castor 30A, followed by two flights of the Antares 120 using an enhanced Castor 30B. The longer Castor 30XL second stage will be used on subsequent ISS resupply flights, allowing Antares to carry larger Enhanced Cygnus.[6][22][23]
Orbital Sciences offers two optional third stages, the Bi-Propellant Third Stage (BTS) and an ATK Star 48-based third stage. BTS is derived from Orbital Sciences' GEOStar spacecraft bus and uses nitrogen tetroxide and hydrazine for propellant; it is intended to precisely place payloads into their final orbits.[2] The Star