In the ever-evolving landscape of space exploration, the Antares 330 stands as a pivotal advancement in medium-lift launch vehicles, designed primarily to support NASA’s Commercial Resupply Services (CRS) missions to the International Space Station (ISS). Developed by Northrop Grumman in collaboration with Firefly Aerospace, this rocket represents a strategic shift towards domestic production and enhanced performance, addressing geopolitical challenges that disrupted previous supply chains. As of November 2025, the Antares 330 is poised to bridge the gap in U.S.-based cargo launches, ensuring reliable access to space for scientific research and station maintenance.
The Antares 330 is a two-stage expendable launch vehicle, building on the heritage of its predecessors while incorporating modern engineering to boost payload capacity and reliability. Standing approximately 42.5 meters tall with a diameter of 3.9 meters, the rocket has a gross liftoff mass around 298,000 kg. It features a 3.9-meter fairing to accommodate larger payloads, and its design emphasizes cost-effectiveness through the use of composite structures and proven avionics systems.
The core innovation of the Antares 330 lies in its redesigned first stage, developed by Firefly Aerospace. This stage is powered by seven Miranda engines, which are liquid-fueled turbopump-fed engines burning RP-1 (rocket-grade kerosene) and liquid oxygen (LOX). Together, these engines generate a total thrust of 7,200 kN (1,600,000 lbf), a significant increase over the previous Antares 230+ model’s 3,844 kN from two RD-181 engines. The Miranda engines utilize a tap-off cycle for efficiency, providing robust liftoff performance. The stage’s composite construction reduces weight while maintaining structural integrity, allowing for improved ascent trajectories.
The upper stage remains the Castor 30XL, a solid rocket motor manufactured by Northrop Grumman. It uses a hydroxyl-terminated polybutadiene (HTPB) propellant bound with aluminum and ammonium perchlorate, delivering a maximum thrust of 474 kN (107,000 lbf) over a burn time of about 156 seconds. With a gross mass of 26,300 kg and 24,200 kg of propellant, this stage provides the final push to insert payloads into low Earth orbit (LEO). Unlike some variants, the Antares 330 typically does not employ a third stage, as the Cygnus spacecraft it launches includes its own service module for orbital maneuvers.
One of the key upgrades in the Antares 330 is its enhanced payload capacity. It can deliver up to 10,800 kg to LEO, a marked improvement over the 8,000 kg limit of earlier Antares models. This boost enables the transport of heavier cargo loads via the Enhanced Cygnus spacecraft, supporting more ambitious ISS resupply missions. The rocket is optimized for launches from the Mid-Atlantic Regional Spaceport (MARS) at Wallops Flight Facility in Virginia, utilizing Launch Pad 0A (LP-0A).
The Antares rocket family traces its roots to NASA’s 2008 Commercial Orbital Transportation Services (COTS) program, where Orbital Sciences Corporation (acquired by Northrop Grumman in 2018) was tasked with developing a reliable cargo delivery system. Early variants, like the Antares 100 series, relied on refurbished Soviet-era NK-33 engines (rebranded as AJ26), but a catastrophic failure during the Orb-3 mission in 2014 – caused by a LOX turbopump explosion – led to a redesign.
The subsequent 200 series introduced Russian RD-181 engines, achieving 10 successful launches from 2016 to 2023. However, the 2022 Russian invasion of Ukraine severed access to these engines and Ukrainian-built components, prompting Northrop Grumman to seek alternatives. In August 2022, a partnership with Firefly Aerospace was announced to co-develop the Antares 300 series, with the 330 configuration specifically tailored for CRS missions.
By mid-2025, Northrop Grumman invested an additional $50 million to accelerate production, renaming a related project to the Eclipse medium launch vehicle while focusing on Antares 330 for immediate needs. This collaboration leverages Firefly’s expertise in rapid development and composite materials, ensuring the rocket meets NASA’s stringent requirements for ISS resupply.
As of November 2025, the Antares 330 remains in active development, with no flights conducted to date. The last launch of the previous Antares 230+ occurred on August 2, 2023, for the NG-19 mission. Interim CRS missions (NG-20 to NG-24) have been handled by SpaceX’s Falcon 9 to maintain supply continuity.
The inaugural flight of the Antares 330 is targeted for no earlier than 2026, carrying the CRS NG-25 mission – a Cygnus spacecraft loaded with cargo for the ISS. Testing of the Miranda engines and integration of the new first stage are progressing, with Northrop Grumman emphasizing domestic sourcing to avoid future disruptions. This positions the Antares 330 as a critical asset in sustaining U.S. space operations.
Looking ahead, the Antares 330 is expected to handle multiple CRS flights under NASA’s CRS-2 contract, potentially extending into the late 2020s. Its success could pave the way for the Medium Launch Vehicle (MLV), a more advanced derivative with a liquid upper stage for even greater versatility. By bolstering American manufacturing in space technology, the Antares 330 not only secures ISS logistics but also contributes to broader goals of sustainable space exploration, including potential applications beyond cargo resupply.
