Northrop Grumman and Firefly’s Antares 330 and MLV plans take shape

by Justin Davenport

As the Cygnus S.S. Laurel Clark spends its first days berthed to the ISS, the successor to the Antares 230+ launch vehicle that launched it is taking shape in the facilities of Northrop Grumman (NG) and Firefly Aerospace. 

The Antares 330/Medium Launch Vehicle (MLV), scheduled for its first flight in mid-2025, is being developed to conduct ISS cargo flights from the Mid-Atlantic Regional Spaceport at Wallops Island, Virginia. Its development started after the Russian invasion of Ukraine in February 2022 crippled the existing Antares supply chain. 

Antares 230+ and its predecessors used Russian engines and a Ukrainian-built first stage. The Russian engines are unavailable after Western nations, including the United States, applied sanctions, while the Ukrainian factory responsible for the first stage has been attacked by Russian forces.

The Antares 330, based on a brand new first stage with seven Firefly Miranda engines using kerosene and liquid oxygen, is designed to use the existing launch and processing facilities that supported the S.S. Laurel Clark and most other NG Commercial Resupply Services (CRS) contract flights. Like earlier versions of Antares, the 330 will fly from Launch Pad 0A at Wallops.

The facilities at Wallops that supported the original Antares launches are being modified to support the Antares 330 and MLV rockets. The pad is being upgraded to accommodate the wider first stage, the transporter erector is being reinforced to handle heavier loads, and the horizontal integration facility is being lengthened to accommodate the longer launch vehicles.

Render of the Antares 330 vehicle. The first stage is to be used on the MLV as well. (Credit: Mack Crawford for NSF)

The Antares 330 first stage is the linchpin of NG and Firefly’s future launch strategy, as it will also be used by the more capable MLV. The first stage’s Miranda engines are each capable of around 1,000 kilonewtons of thrust. Seven of these engines would generate just under 7,200 kilonewtons of thrust in a vacuum, which would be nearly double the thrust of the Antares 230+ first stage at 3,800 kilonewtons.

This stage will be made out of carbon composite materials, like Rocket Lab’s Electron and Firefly’s Alpha rocket. Carbon composite assemblies aim to make the stage as lightweight as possible.

The Miranda engine is currently in the development and testing phase. “Stubby” combustion chamber test articles have been built for initial testing of the engine, while the first full-size Miranda test article is being readied as well. Miranda engines will be mass-produced at Firefly Aerospace’s manufacturing and test facility in Briggs, Texas.

The Antares 330 first stage, measuring 31 meters high and 4.3 meters in diameter, will also incorporate NG’s MACH avionics, which has been used on prior Antares vehicles. Like the Antares 230+, the Antares 330 will use the Castor 30XL solid rocket motor for its upper stage as well as the same payload fairing.

The Castor 30XL solid propellant second stage of the Antares rocket that will take the NG-13 Cygnus to orbit. (Credit: Jacques van Oene for NSF)

Antares 330 has a projected payload capacity of up to 10,500 kilograms to low-Earth orbit, as opposed to the Antares 230+ capacity of up to 8,120 kilograms to low-Earth orbit. This will enable heavier cargo loads to be sent up to ISS as part of the company’s CRS-2 contract.

The MLV is a follow-on vehicle that will use the Antares 330 first stage along with a new liquid-fueled upper stage sporting a vacuum-optimized Miranda engine. Like other vacuum-optimized rocket engines, the upper stage’s Miranda engine will feature a much larger nozzle than the first stage engines will use. This enables the engine to function more efficiently at higher altitudes – the only region the engine will be firing in.

The first Miranda “stubby” combustion chamber test article. (Credit: Firefly Aerospace)

Like the first stage, the second stage will also feature carbon composite construction. Both stages will use graphite/epoxy tanks with a common dome, as well as the aforementioned NG MACH avionics. The second stage will be the same diameter as the first stage, while the carbon composite fairing will have a diameter of 5.2 meters along with pneumatic separation fittings and actuators.

MLV specifications and rendering. (Credit: Firefly Aerospace)

The MLV is also set to be offered with an optional third stage based on one Firefly Lightning-based engine. Lightning has been successfully used on the Firefly Alpha rocket, while work that had gone into the Firefly Beta concept will now be used with MLV. NG had offered three optional third stage choices for earlier Antares vehicles, but those vehicles never saw other customers besides NASA for anything more than small CubeSats.

The MLV’s current listed payload capacity is up to 16,000 kilograms to a 200-kilometer circular low-Earth orbit inclined 38 degrees to the Equator. After the MLV was first announced, its capability to geosynchronous transfer orbit was listed as 2,750 kilograms, though any updated figures are not currently public. 

Aerial view of Wallops Flight Facility. (Credit: NASA)

MLV is currently set to fly from Wallops Island, and it remains to be seen whether it will be used for other launch sites. NG envisages MLV being offered for National Security Space Launch (NSSL) Phase 3 Lane 1 missions, which do not require the use of all of the Space Force’s launch facilities. These missions also have less stringent requirements on the types of orbits the vehicle can reach. The MLV’s fairing meets NSSL Category B requirements. 

The MLV is also planned to be offered for NASA Launch Services Program missions and Venture-class Acquisition of Dedicated and Rideshare (VADR) flights, which are higher-risk and lost-cost NASA satellite missions. Private satellite constellations, commercial space stations in low-Earth orbit, and US Department of Defense Rocket Systems Launch Program flights are listed as possible MLV clients as well.

The MLV is joining an increasingly crowded field of competitors in the medium launch services space. Rocket Lab’s Neutron, which is partially reusable, is specified as having similar capabilities to the MLV – not to mention launching from just a half-kilometer away from Pad 0A – while the ULA Vulcan, Arianespace Ariane 6, India’s LVM3, and Japan’s H3 will also be competing for launch business.

Blue Origin’s New Glenn will soon be in the mix for numerous launch contracts, with the added bonus of its superior capability compared to all the aforementioned vehicles. Meanwhile, the SpaceX Falcon 9 continues to demonstrate strong reliability, low cost, and high flight cadence for light, medium, and heavy payloads.

(Lead image: Artist’s impression of the NG/Firefly MLV lifting off. Credit: Firefly Aerospace)

Related Articles