The Antares 230+ rocket

Northrop Grumman's Antares 230+ rocket

The Antares 230+ has been the latest iteration of the Antares launch vehicle and has successfully launched Cygnus resupply spacecraft to the International Space Station.

The inaugural Antares 230+ launches from Pad 0A at the Mid-Atlantic Regional Spaceport on Nov. 2, 2019, for the NG-12 mission to the International Space Station. Credit: Joseph Navin

About the rocket

The Antares rocket is a launch vehicle that was originally developed by Orbital Sciences Corporation to compete in NASA's Commercial Orbital Transportation Services (COTS) and the Commercial Resupply Services (CRS) contracts. The vehicle was originally known as the Taurus II.

The vehicle launches from Pad 0A at the Mid-Atlantic Regional Spaceport, located at NASA's Wallops Island Flight Facility in Virginia.

Pad 0A previously was originally used for the only launch of the Conestoga 1620 in 1995 and was rebuilt for the Antares rocket. The pad is located beside Rocket Lab's Launch Complex-2 (also known as Pad 0C.

Both 100 and 200-series versions of Antares consist of a first stage built by the Ukrainian manufacturer Yuzhmash and Yuzhnoye in Dnipro, Ukraine. The first stage is based on the Soviet and Russian Zenit rocket.

The 100-series variant of the Antares rocket used two Aerojet AJ-26 engines on the first stage. These engines were retooled Soviet Kuznetsov NK-33 engines which were used on the Soviet N-1 rocket. The variant also used the American Castor 30 solid rocket motor as the second stage.

The Antares 100 launched on its maiden flight on the Antares A-ONE test flight in 2013. After a few missions, Antares experienced its only failure on the CRS ORB-3 mission.

This failure led to Orbital Sciences changing the engines on the first stage to the Energomash RD-181, two of which are used on the 200-Series of the Antares. The 200-series also uses the larger Castor 30XL upper stage.

Orbital Science would go on to experience numerous corporate mergers, becoming Orbital ATK and later merging with Northrop Grumman.

The Antares 230+ version launched for the first time on the NG-12 mission on Nov. 2, 2019. This variant incorporated numerous small upgrades. This included the ability for late-load cargo on the Cygnus resupply spacecraft though the use of the "pop-top" fairing.

This means that Northrop Grumman can remove the top of the fairing inside a mobile cleanroom on the pad 24 hours prior to launch.

After the Russian Invasion of Ukraine, the international situation made the 230+ variant of the Antares unfeasible. Northrop Grumman is working with Firefly Aerospace to create the Antares 330 variant. This will feature a larger diameter first stage with seven Miranda engines.

Rocket Lab's Launch Complex-2 is seen during the final stages of construction next to Antares atop Pad 0A in Feb. 2020. Credit: Joseph Navin

The maiden flight of the Antares 230+ launches on Nov. 2, 2019, during the NG-12 mission. Credit: Joseph Navin

The core booster on the Antares 230+ is seen venting during RP-1 and LOX fuel loading prior to liftoff on Nov. 2, 2019, ahead of the NG-12 mission. Credit: Joseph Navin.

Pad workers walk south down North Seawall Road toward Pad 0A on Wallops Island in Virginia a day prior to the first Antares launch attempt for the NG-13 mission in February 2020. Credit: Joseph Navin.

NASASpaceflight's own John "Das" Galloway operates a camera toward the Antares 230+ rocket. This was part of a NASASpaceflight Livestream of NG-13 pre-launch events on Wallops Island in Virginia a day prior to the first Antares launch attempt for the NG-13 mission in February 2020. Credit: Joseph Navin.

Rocket hardware

Antares 230+ core stage

The engine section of the Antares 230+ first stage is seen during an NG-13 press event inside the Horizontal Integration Facility or HIF on Wallops Island, Va. in February 2020 prior to RD-181 engine installation. This first stage would later fly on the NG-14 mission. Credit: Joseph Navin.

The first stage of the Antares 230+ features as mentioned earlier two RD-181 engines. These engines are similar to the single RD-180 engine featured on United Launch Alliance's Atlas V rocket and another similar variant is the RD-191 which is used on Russia's Angara family of rockets and was used on the South Korean Naro-1 rocket.

In the photo above, the first stage engine section of the Antares 230+ rocket is seen Inside the Horizontal Integration Facility prior to it's flight on the NG-14 mission. The image shows what the engine section looks like prior to RD-181 engine installation. In the back of the engine section the aft bulkhead for the RP-1 Kerosene tank is seen with the middle of the bulkhead featuring the attachment to the Liquid Oxygen (LOX) downcomer.

On the diameter of the engine shroud, the four hold-down interfaces between the rocket and the launch pad can also be seen At liftoff the explosive bolts fire to release the rocket from the launch pad as it ascends. At the top-center of the vehicle diameter, the umbilical interfaces with the pad can also be seen.

Production of the final Antares 230+ first-stage booster by Yuzhmash and Yuzhnoye in Dnipro, Ukraine has been completed with the 2022 Russian Invasion of Ukraine. The booster will be replaced by the aforementioned Antares 330 first-stage core booster by Firefly Aerospace.

In an interview conducted with Kurt Eberly, the Director of Space Launch for Northrop Grumman by Joseph for NASASpaceflight, Eberly hinted at a future derivative launch vehicle that is also under development between Northrop Grumman and Firefly Aerospace.

“We’re going to then take that same first stage for the Antares 330 and then we’re going to develop with Firefly a new liquid second stage with a bigger fairing,” said Eberly. “We are calling it the medium launch vehicle and we’re gonna go through a naming contest internally with our employees here…both us and Firefly. We’ll see who wins. But that capability we’re targeting for debut in late 2025. We think that’s really going to be a powerful competitor.”

The two RD-181 engines on the Antares 230+ rocket are seen in February 2020. This rocket was launched on the NG-13 mission. Credit: Joseph Navin

Castor 30XL

The Castor 30XL destined for the NG-13 mission is seen inside the Horizontal Integration Facility on Nov. 1, 2019, during the pre-launch press event for NG-12. The name and logo of Orbital ATK is seen on the stage as it was manufactured prior to Orbital ATK's merger with Northrop Grumman. Credit: Joseph Navin.

The second stage of the Antares 230+ rocket is the previously mentioned Castor 30XL solid rocket motor. The use of a solid rocket motor on a second stage, with a liquid-fuelled first stage, is a rare combination for a launch vehicle.

The Castor 30XL is a stretched variant of the Castor 30 used on the Antares-100 series. The Castor family of rocket motors originated on the Scout X-1 rocket which also launched from Wallops Island. Current motors in the Castor series of motors has flown on Northrop Grumman's Minotaur-C and Antares.

According to Northrop Grumman, the Castor 30XL runs on solid rocket propellant which includes QDL-1, HTPB (Hydroxyl-terminated polybutadiene) Polymer, and 19% aluminum. Once ignited, the motor burns for 155 seconds, during which the motor produces a maximum of 119,900 pounds of thrust.

The Castor 30XL destined for the NG-14 mission is seen inside the Horizontal Integration Facility in February 2020, during the pre-launch press event for NG-13 mission. Credit: Joseph Navin.

The solid rocket motor on the Castor 30XL is designed to be used in the upper levels of the atmosphere and in the vacuum environment of space. The vacuum-optimized nozzle on the stage is eight feet long and has an expansion ratio of 55.9:1.

According to Northrop Grumman, the motor features an "electro-mechanical thrust vector actuation system" which moves the nozzle of the motor to steer the vehicle. This system also features an electronic controller and a thermal battery.

In an interview by Joseph Navin with Kurt Eberly for an article with NASASpaceflight, Eberly described the maneuvers that Northrop Grumman controllers direct to the Castor 30XL prior to the end of the launch period of the mission. This comes after the separation of the Cygnus spacecraft from the second stage.

“After separation, we do a couple maneuvers with the upper stage just to make sure there’s no recontact between us and Cygnus using our attitude control system,” said Eberly. “So we kind of do a crab walk maneuver to back away to make sure that there’s good separation between us and Cygnus.”

The Castor 30XL will continue to fly on the Antares 330 vehicle.

The Castor 30XL destined for the NG-14 mission is seen inside the Horizontal Integration Facility in front of the core first stage booster in February 2020, during the pre-launch press event for NG-13 mission. Credit: Joseph Navin.