The final flight of the Antares 230+ launch vehicle, marking the end of the career of Northrop Grumman’s Antares 200 series of rockets, lifted off Tuesday with the NG-19 mission under the Commercial Resupply Services cargo contract to supply the International Space Station.
The Commercial Resupply Services (CRS) NG-19 flight launched from LP-0A at the Mid-Atlantic Regional Spaceport (MARS) on Wallops Island, Virginia, at 8:31 PM EDT (00:31 UTC on Wednesday). Following a southeasterly trajectory, Antares carried the Cygnus cargo ship into orbit. Continuing the tradition of naming Cygnus spacecraft, the vehicle that flew the NG-19 mission is named the S.S. Laurel Clark after one of the astronauts lost aboard Space Shuttle Columbia when it disintegrated during re-entry in February 2003.
S.S. Laurel Clark was loaded with over 3,700 kilograms of cargo destined for the International Space Station. Antares placed it into an initial 165-by-309 kilometer low-Earth orbit, inclined 51.64 degrees to the Equator. From there, the Cygnus spacecraft will maneuver itself to set up rendezvous with ISS, arriving just over two days after liftoff. On arrival, it will be captured using the Station’s Canadarm2 robotic arm and berthed to the Unity module’s Earth-facing port.
Capture of the S.S. Laurel Clark is currently scheduled for 09:55 UTC on Friday. Berthing to the Unity module would be expected to occur around two hours after the capture. Astronaut Woody Hoburg will be operating Canadarm2, with Frank Rubio as his backup.
Cygnus is carrying a number of science experiments to the Station. Among them are a gene therapy experiment known as Neuronix that can form 3D neuron cell cultures in microgravity. Neuron-specific therapies that can treat diseases like Alzheimer’s and Parkinson’s may become possible due to the research performed.
The Multi-Needle Langmuir Probe is designed to study the ionosphere. The ISS orbits near the peak plasma density region of the ionosphere and this experiment can measure small plasma structures. These structures can affect the accuracy of systems such as satellite navigation.
There is also a new water system aboard the Cygnus that will be tested on board the Station. The Exploration PWD system uses advanced water sanitization and microbial growth reduction methods, and can also produce hot water. It can be commanded from the ground and can collect data, telemetry, and self-diagnostics.
S.S. Laurel Clark also carries a memory card commissioned by the Japan Aerospace Exploration Agency (JAXA) containing art and poetry from more than 13,000 students in 74 schools. This project is known as the I-Space Essay.
Once berthed to the Station, Cygnus can stay attached for up to 100 days. S.S. Laurel Clark, like its predecessors, can also fly autonomously in free flight for up to 30 days. After leaving the Station, S.S. Laurel Clark will conduct the last of a series of fire safety in space experiments and deploy several CubeSats before it re-enters the atmosphere.
The SAFFIRE VI experiment is the last in a series that has already changed our understanding of the flammability of materials in low-gravity environments. These experiments have evaluated the flammability of materials at different oxygen levels, fire detection and monitoring systems, and post-fire cleanup. The SAFFIRE series has demonstrated that smoke inhalation is the most immediate hazard to the crew, similar to fires on Earth.
The DUPLEX (Dual Propulsion Experiment) 6U CubeSat will be deployed from Cygnus after unberthing from ISS, into an approximately 470-kilometer circular orbit. This CubeSat will test two polymer fiber propulsion systems and a new sensor system during its flight. CU Aerospace of Champaign, Illinois was granted a NASA Tipping Point partnership award for developing this spacecraft.
Also listed as flying on this mission are two Virginia Space CubeSat Program (VSCP) satellites – VSCP-1A and VSCP-1B – which are 3U CubeSats. These satellites, developed by Old Dominion University and Virginia Tech, respectively, will be deployed into a 170-by-260-kilometer low-Earth orbit.
Between them, these satellites will be flying an impedance probe, a multispectral sensor, a deployable composite structure, and a memory exposure experiment. The Old Dominion satellite, developed with the US Coast Guard Academy as a partner, is also known as SeaLion, while the Virginia Tech satellite is also known as the Ut ProSat-1.
Once the S.S. Laurel Clark is done with its deployments and experiments, it will end its mission with a destructive re-entry into Earth’s atmosphere. This will take place over a corridor in the Pacific Ocean away from shipping lanes. Before unberthing, trash from the ISS will have been loaded into the spacecraft for disposal as it re-enters.
Throughout its career, the Cygnus spacecraft has disposed of around 41,276 kilograms (91,000 pounds) of trash during destructive reentries. Cygnus has also carried around 58,967 kilograms (130,000 pounds) of cargo to the Station during nearly a decade of flights.
The Antares launch vehicle has been through several iterations. All of these variants, starting with the Antares 110, have been powered by a Ukrainian-built first stage with Russian-made engines and a second stage using a solid-fueled Castor 30 series motor made by what is now the Northrop Grumman propulsion systems division.
The Antares 110 and 120 completed two successful flights each, starting in April 2013, powered by NK-33 engines imported from Russia and reworked by Aerojet Rocketdyne as the AJ-26. Two of these engines were fitted on a first stage built by Yuzhmash – now known as Pivdenmash – based in Dnipro, Ukraine, which also manufactured the Zenit rocket.
The fifth Antares launch, with the CRS Orb-3 mission, marked the first flight of the Antares 130 rocket. These early missions had designations beginning with “Orb” for the original developer of Antares and Cygnus, Orbital Sciences Corporation. This was changed to OA after the company became Orbital ATK following a 2015 merger, and NG after it was bought by Northrop Grumman in 2018.
Antares 130’s second stage was an upgraded version of the Castor 30 upper stage known as the Castor 30XL. This configuration was only used for the Orb-3 mission.
The Orb-3 Cygnus spacecraft, S.S. Deke Slayton, was supposed to carry 2,215 kilograms of cargo up to the ISS, but one of the Antares rocket’s AJ-26 first-stage engines suffered a severe turbopump failure 15 seconds after liftoff. The resulting damage caused the engines to shut down and Antares to fall back toward the launch pad before exploding after the flight termination system was activated.
The AJ-26 engine was retired after the failure, and RD-181 engines, also using kerosene and liquid oxygen, were ordered from Russia’s NPO Energomash for the Antares 230 series that started flying in October 2016. The Antares 230 made five successful flights before the current Antares 230+ made its debut in November 2019 on the NG-12 mission.
The Antares 230+, which has made seven successful flights to date, was developed to fulfill Northrop Grumman’s commitments under the CRS-2 contract, which started with the NG-12 mission. This version of the rocket features structural upgrades to the intertank and forward bays, allowing it to carry up to 8,000 kilograms of payload to low-Earth orbit.
A late-load capability is also available to the Cygnus spacecraft through a “pop top” nose cone and mobile payload processing facility. This was first demonstrated on the last original CRS and Antares 230 flight, NG-11, in the spring of 2019, and is a key capability for the CRS-2 missions.
Russia’s invasion of Ukraine, which began in February 2022, placed the supply chain for the Antares 230+ in jeopardy. Sanctions have prevented the purchase of new engines from Russia, and the Pivdenmash factory in Dnipro has been attacked by Russian forces. Therefore, Northrop Grumman has decided to retire the current Antares vehicle after building out the final rockets with supplies on hand.
Northrop Grumman has entered an agreement with Firefly Aerospace to produce the first stage of the Antares 330 series. The Antares 330, whose first flight is now expected sometime in mid-2025, will use seven of Firefly’s Miranda engines, which, like the AJ-26 and RD-181, use kerosene and liquid oxygen as propellants.
The Antares 330, designed to use the same launch facilities at Wallops as the original Antares versions, will launch with 7,200 kilonewtons of thrust — a substantial increase over the Antares 230+’s 3,844 kilonewtons. As a result, the Antares 330 will be capable of flying heavier payloads than previous Antares vehicles. Like the Antares 230 series, it will retain the Castor 30XL upper stage.
The Cygnus spacecraft itself has also experienced an evolution in capability. The spacecraft, consisting of a Pressurized Cargo Module (PCM) built by Thales Alenia Space of Italy, and a Service Module (SM) built by Northrop Grumman, can currently carry up to 3,750 kilograms of cargo to the ISS. Since its introduction, Cygnus has also gained the ability to reboost the Station’s orbit. This capability was first demonstrated by the S.S. Piers Sellers during the NG-17 mission in June 2022.
The PCM was first flown as a “standard” version on the first four flights of Cygnus, including the failed Orb-3 mission. The Standard Cygnus PCM had an internal volume of 18 cubic meters and was capable of carrying up to 2,000 kilograms to ISS. The Enhanced Cygnus PCM – introduced on the fifth mission, OA-4 – has an internal volume of 27 cubic meters and can carry over 3,200 kilograms to ISS when launching aboard Antares.
The Enhanced Cygnus SM uses lighter circular solar panels, which unfold like a fan, in place of the Standard Cygnus SM’s rectangular panels. These can produce just as much power – up to 3.5 kilowatts – as the original solar panels at a lower mass. During the NG-18 mission last year, Cygnus demonstrated the ability to function on just one solar array after its second panel failed to deploy.
NG-18, the S.S. Sally Ride, launched on Nov. 7, 2022. During a staging event, acoustic blanket material from inside the fairing jammed one of the solar array deployment mechanisms. The Cygnus spacecraft was able to complete its rendezvous and berthing to ISS on just the remaining array, and changes have been made to prevent a recurrence on NG-19.
Cygnus is also capable of flying on launch vehicles besides the Antares, which came in handy when Antares was grounded after the October 2014 Orb-3 failure. Orbital Sciences contracted with United Launch Alliance (ULA) to fly two Cygnus spacecraft aboard its Atlas V rocket in 2015 and 2016. These missions were the first to fly the Enhanced Cygnus, which has flown all Cygnus missions since, as the Standard Cygnus is retired.
After NG-19, Northrop Grumman has contracted with SpaceX for three Cygnus flights on its Falcon 9 rocket while the Antares 330 is under development. The Enhanced Cygnus also forms the basis of the Habitation and Logistics Outpost (HALO) module for the Lunar Gateway, which is scheduled to start assembly in lunar orbit later this decade.
(Lead image: The Antares 230+ launch vehicle lifts off from LP-0A at the Mid-Atlantic Regional Spaceport on Wallops Island. Credit: Max Evans)