Antares rocket: the ultimate outsourcing

Formerly known as Taurus-2, the Antares rocket is officially an American space launcher developed by the Virginia-based Orbital Sciences Corporation, OSC, (now known as Orbital ATK). However, in reality, Orbital outsourced the production of the rocket's booster stage to Ukraine and ordered its main engines in Russia. In a bizarre irony of the post-Cold War politics, Ukraine and Russia continued building the rocket for the US, even as the two former Soviet republics essentially went to war with each other in 2014.

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Evolution of the Antares design: the depiction of Taurus-2 circa 2009 (left) and the Antares vehicle (2016).

The Antares (Taurus-2) rocket family at a glance:

Number of stages
Cygnus cargo ship
Liftoff mass
275.000 kilograms (Taurus-2) 292,887 kilograms (Antares-230)
Payload to low Earth orbit (ISS)
5,200 - 5,400 kilograms
Total length
40.1 meters (Taurus-2) - 42.5 meters (Antares-230)
Main diameter
3.9 meters
Payload fairing dimensions
3.9 by 9.9 meters
Launch site
Wallops Island, Virginia, Pad 0A
Stage I propulsion
RD-181 engine (Liquid oxygen oxidizer and kerosene fuel)*
Stage I propellant load
239,280 kilograms
Stage I burn time
~209 seconds
Stage I total thrust
4,170 kilonewtons
Stage II propulsion
Castor-30A, -30B, -30XL solid motors
Stage II fueled mass (Castor-30XL)
25,000 kilograms
Stage II length (Castor-30XL)
5.0 meters
Stage II diameter (Castor-30XL)
2.36 meters
Stage II thrust (Castor-30XL)
464 kilonewtons (average) 533 kilonewtons (maximum)
Stage II burn time (Castor-30XL)
~163 seconds

*Replaced the NK-33/AJ26 engine in the original version of the Antares rocket.

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From Taurus-2 to Antares

The Orbital Sciences Corporation, OSC, proposed its Taurus-2 design in a bid for a NASA program known as Commercial Orbital Transportation Services, COTS, which sought to develop low-cost access to the International Space Station, ISS. With the COTS program, NASA hoped to largely transfer routine ISS transport operations to private contractors. Obviously, all bidders in the COTS program were under pressure to provide the cheapest possible access to orbit.

It was a hallmark of post-industrial America, for US businesses to achieve competitive edge by outsourcing jobs and production to developing countries with cheap labor forces. OSC brought this principle to a whole new level, becoming the first American company to actually outsource the production of a sophisticated space booster. Even more ironically, the Ukrainian-built first stage of the OSC's Taurus-2 rocket would be propelled by a pair of the Soviet-era NK-33 engines left over from the the N1-L3 Moon project, which aimed to beat the Apollo astronauts to the Moon. In the 1990s, US businessmen located and purchased surviving NK-33 engines in Russia. After refurbishment and testing the engine in the US, the Aerojet company certified the NK-33 for flight under the designation AJ26. On the Antares, the NK-33/AJ26 was attached to the rocket via a newly designed gimbal mechanism, which enabled it to rotate the combustion chamber in flight and thus steer the entire rocket in flight. (On the N1, flight control was accomplished by varying thrust of individual engines, which were all installed in fixed positions on the rocket. The Russian Soyuz-2-1v rocket, which also adopted the NK-33, featured a specially designed steering thruster, while the single NK-33 engine remained in fixed position.)

To build the first stage for the Taurus-2, KB Yuzhnoe in Dnepropetrovsk, Ukraine, relied on the design of the Zenit rocket, the latest and the most advanced booster developed in the USSR before its disintegration in 1991. KB Yuzhnoe was able to dramatically cut the development cost by using the existing machinery of the Zenit production line, which was still in operation at the time. Not coincidently, Zenit had a diameter of 3.9 meters, which was also chosen for the Taurus-2 rocket.

Upper stages

To complete the two-stage Taurus-2 rocket, the Ukrainian booster would be topped with OSC's own Castor-30A solid-propellant motor manufactured at the facility of the former Thiokol company in Utah, which eventually merged with OSC to form Orbital ATK. Thiokol previously supplied solid motors for OSC's previous launchers such as the air-launched Pegasus and the ground-based Minotaur and Taurus-1. Eventually, the 30B and 30XL variants of the Castor motor were developed.

Theoretically, the Taurus-2 could be equipped with a third stage, which could use storable liquid propellant.

Launch pad


The Taurus-2 rocket was based at the historic American launch site on the Wallops Island, off the coast of Virginia, which previously hosted the light-weight Scout launchers. According to Orbital ATK, the rocket could also fly from Vandenberg Air Force Base, California, Cape Canaveral, Florida, and Kodiak Island, off the coast of Alaska.

The first launch of the Taurus-2 was originally expected in 2010, but it actually took place on April 21, 2013.

In the course of its flight history, several modifications of the Antares rocket have been built and its name reflected these upgrades according to the following convention:

naming convention

Antares-Cygnus system


Astronauts onboard the International Space Station use a robotic arm to attach the first Cygnus cargo ship to the US segment of the station in 2013. Credit: NASA

For resupply missions to the International Space Station, Taurus-2 carries the Cygnus cargo ship, capable of accommodating up to 3,515 kilograms of supplies in its pressurized cargo module. The pressurized section is manufactured by Thales Alenia Space in Turin, Italy, which previously built similar structures for the Space Shuttle's Spacelab and Spacehab modules, for the European Columbus module and for cargo modules of the International Space Station.

The service module for the spacecraft is manufactured by Orbital ATK in Dulles, Virginia.

After several days in solo flight, Cygnus automatically approaches the ISS up to a distance of 12 meters with the help of satellite navigation and laser imaging. The ISS crew then uses the station's robotic arm to grab the ship and dock it to the US segment.

The ship can remain attached to the ISS for a period of up to 90 days, after which it is released in orbit for a destructive reentry into the Earth's atmosphere.

In 2016, Orbital ATK quoted six planned missions to the ISS through 2018 and under a second NASA contract -- CRS2 -- for another six missions, beginning in 2019. According to the company, a total of more than 50 tons of cargo would be delivered to the ISS from 2013 to 2024.

The disaster and the Ukrainian conflict


On October 28, 2014, after four successful launches, the upgraded Antares-130 rocket carrying Cygnus Orb-3 cargo ship to the International Space Station, ISS, exploded seconds after liftoff due to a failure of the first-stage engine. After the accident, Orbital was apparently compelled to immediately replace the controversial Soviet engines rather than to fix the problem, as it would be done after a "typical" launch accident.

Ironically, the company had nowhere to go but to another Russian manufacturer, NPO Energomash, for the replacement of the discredited NK-33 engines. It chose a variant of the RD-191 engine, which was originally developed for the first stage of the Angara rocket and was sold to the US under name RD-181.

In another irony, the NK-33 performed just fine on the Russian Soyuz-2-1v rocket launched after the 2014 accident. However, the strangest situation was that at the time, Russia annexed Crimea and began a proxy war in Ukraine, leading to the breakup of many economic ties between the two former Soviet republics and triggering Western sanctions against Moscow. Yet, Ukraine and Russia still continued their respective roles in the Antares project and the US government apparently decided to preserve the program.

On Oct. 2, 2015, another booster for the Antares rocket came off the production line in Dnepropetrovsk, Ukraine, and Ukrainian space officials said that they had contracts with Orbital ATK covering the work until 2019.

Unfortunately, the surviving space cooperation project did seemingly little to ease tensions between Russia and Ukraine. In 2016, the head of NPO Energomash company found it necessary to boast in the official Russian media that his team had no interaction with their Ukrainian colleagues during work on the Antares rocket.

Return to flight

Despite all the political problem, the Antares rocket was brought back to the launch pad in October 2016. After a 24-delay due to a ground support equipment cable that did not perform as expected during the pre-launch checkout, the countdown was resumed on October 17.

The rocket lifted off at the end of its five-minute launch window, after last-minute checks of the propulsion system. Nine minutes later, the vehicle successfully delivered a Cygnus spacecraft into orbit.


A complete list of Antares launches:

Launch date
Time of launch
2013 April 21
5 p.m. EDT
Cygnus mass simulator, DOVE-1, PhoneSat v1a, PhoneSat v1b, PhoneSat v1c
2013 Sept. 18
10:58:02 a.m. EDT
Cygnus Orb-D1 (COTS Demo)
2014 Jan. 9
1:07:05 p.m. EST
Cygnus (Orb-1)
2014 July 13
12:52 p.m. EDT
Cygnus Orb-2 (CRS-2)
2014 Oct. 28
6:22:38 p.m. EDT
Cygnus Orb-3 (CRS-3)
2016 Oct. 17
7:45:40 p.m. EDT
Cygnus CRS OA-5
2017 Nov. 12
7:19:55 a.m. EST
Cygnus CRS-8 OA-8
2018 May 21
4:44:09.7 a.m. EDT
Cygnus OA9 (CRS-9)
2018 Nov. 17
4:01 a.m. EST
Cygnus-10 (CRS-10, NG-10, John Young)
10 2019 April 17 4:46 p.m EDT Cygnus NG-11 (CRS-11, Roger Chaffee)
11 2019 Nov. 2 9:59 a.m. Eastern Time Cygnus NG-12 (CRS-12, Alan Bean)
12 2020 Feb. 16 3:21:04.9 p.m. EST Cygnus NG-13 (CRS-13, S.S. Robert Lawrence, Jr.)
2020 Oct. 2
9:16:14 p.m. EDT
Cygnus NG-14 (CRS-14, S.S. Kalpana Chawla)
14 2021 Feb. 20 12:36 p.m. EST Cygnus NG-15 (CRS-15, S.S. Kathrine Johnson)
15 2021 Aug. 10 6:01:09.300 p.m. EDT Cygnus NG-16 (CRS-16, Onizuka)
16 2022 Feb. 19 12:40 p.m. EST Cygnus NG-17 (CRS-17, S.S. Piers Sellers)
17 2022 Nov. 17 5:32 a.m. EDT Cygnus NG-18 (CRS-18, S.S. Sally Ride)
18 2023 Aug. 1 8:31:14 p.m. EDT Cygnus NG-19 (CRS-19, S.S. Laurel Clark)


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The article by Anatoly Zak; Last update: August 1, 2023

Page editor: Alain Chabot; Last edit: October 18, 2016

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The NK-33 rocket engine. Click to enlarge. Copyright © 2010 Anatoly Zak


An Antares rocket lifts off in on July 13, 2014, with the CRS Orb-2 cargo supply mission to the ISS. Click to enlarge. Credit: BIll Ingalls / NASA


The Antares-130 rocket lifts off on Oct. 28, 2014. Click to enlarge. Credit: NASA


Two RD-181 engines that arrived in July are being integrated with the Antares first stage air frame at the Wallops Island, Virginia Horizontal Integration Facility (HIF). A “hot fire” test on Pad 0A is scheduled for late 2015 or early 2016.


Orbital ATK's Cygnus cargo craft is released from the International Space Station in this June 14, 2016, photograph by ESA astronaut Tim Peake. Once Cygnus reached a safe distance, ground controllers at NASA's Glenn Research Center initiated the sequence for an experiment design to better understand how fire spreads in a microgravity environment. Credit: NASA


Castor-3XL stage. Credit: NASA