Eclipse (rocket)
| Company type | Private |
|---|---|
| Industry | Aerospace |
| Founded | 2017 |
| Headquarters | Briggs, Texas , United States |
| Products | Eclipse rocket, Alpha rocket, Antares 330 (in collaboration) |
Eclipse, previously known as Firefly Beta and the Medium Launch Vehicle (MLV), is a two-stage medium-lift rocket with partial reusability, developed collaboratively by Firefly Aerospace and Northrop Grumman. Introduced in 2022, it is intended to replace Northrop Grumman's Antares by incorporating reusable elements and offering a payload capability of 16,300 kg (35,900 lb) to low Earth orbit. The inaugural launch is planned for late 2026.
Firefly Beta
The origins of Eclipse trace back to the late 2010s following the dissolution of Firefly Space Systems in 2017 and its subsequent reestablishment as Firefly Aerospace. Initially designated Firefly Beta, it aligned with the naming convention set by the smaller Firefly Alpha vehicle. Early concepts involved clustering three Alpha cores similarly to the Delta IV Heavy or Falcon Heavy. By 2020, this approach shifted to a larger Alpha-based design featuring a first stage diameter of 3.7 m, a 4.7 m payload fairing, and five Reaver 2 engines powering the initial stage. The Beta configuration was estimated to deliver 8,000 kg (17,600 lb) to LEO and 5,800 kg (12,800 lb) to Sun-synchronous orbit, with an anticipated maiden flight scheduled for late 2024.
In October 2019, Firefly entered a partnership with Aerojet Rocketdyne aiming to develop a launch vehicle powered by the AR1 engine; however, it remains uncertain if this collaboration advanced beyond preliminary design stages.
Partnership with Northrop Grumman
On August 8, 2022, Firefly and Northrop Grumman announced a joint effort to advance both Beta and Antares.<ref> Antares was originally operated by Orbital Sciences Corporation (later known as Orbital ATK) before Northrop Grumman acquired the company in 2018. Its first stage utilized Ukrainian manufacturing and two Russian RD-181 engines. The disruption caused by Russia’s 2022 invasion of Ukraine interrupted this supply chain, compelling Northrop Grumman to explore alternative solutions for Antares.
The Beta vehicle was rebranded as the Medium Launch Vehicle (MLV) and underwent redesigns including a de-rated first stage variant intended for use in the new Antares 300-series.<ref> Positioned as Antares’s successor, the MLV will be complemented by the Antares 300-series which is slated to support three Cygnus missions during MLV’s development phase. Both rockets are planned to operate from Wallops Island in Virginia.
Transition to Eclipse
In February 2024, Firefly expanded its manufacturing site in Briggs, Texas from 8,550 m2 to 19,230 m2, facilitating production capabilities for both MLV and Antares 330 rockets.<ref> By April of that year, production began on the Miranda engines for these vehicles.
During summer 2024, Firefly and Northrop Grumman revealed plans for a partially reusable MLV design incorporating return-to-launch-site (RTLS) functionality for the first stage, targeting operational reuse starting from the sixth flight.<ref>
On May 29, 2025, Northrop Grumman invested US$50 million into Firefly’s collaborative rocket program. At this time, the Medium Launch Vehicle officially received its new name: Eclipse.<ref>
Design
Eclipse employs RP-1 fuel combined with LOX oxidizer across both stages and features a carbon-fiber composite structure derived from Alpha’s manufacturing techniques. The rocket stands 55.7 m (183 ft) tall with a diameter of 4.32 m (14.2 ft). Its payload fairings measure 5.4 m (17.7 ft) in width and can be tailored to accommodate different cargo requirements.
The first stage is equipped with seven Miranda engines utilizing a tap-off cycle, generating thrust with a specific impulse of 305 seconds. This stage is engineered for reusability; however, a downgraded expendable variant will serve as the first stage for the Antares 330. The second stage relies on one Vira vacuum engine delivering thrust at an impulse of 328 seconds. This upper stage is expendable and must be replaced after each mission.
Operations
Eclipse's initial launch activities are scheduled to take place at Launch Pad 0A (LP-0A), located within the Mid-Atlantic Regional Spaceport (MARS) at Wallops Flight Facility, Virginia. Constructed in the 1990s originally for the Conestoga program, LP-0A served as the launch site for Antares 100 and 200 series rockets between 2013 and 2023, benefiting from engine commonalities with the Antares 330 variant. This launch pad will be utilized by both Eclipse and Alpha vehicles, enabling adaptable scheduling and operations.
For missions targeting polar orbits, Eclipse will operate from Space Launch Complex 2 West (SLC-2W) at Vandenberg Space Force Base, California. Historically used for Thor and Delta launches, Firefly acquired this facility following the retirement of the Delta II in 2018. Currently, it serves as the launch site for Alpha missions. SLC-2W is equipped to support launches of both Alpha and Eclipse rockets.
In addition, Firefly and Northrop Grumman intend to utilize Space Launch Complex 20 (SLC-20) at Cape Canaveral Space Force Station, Florida, for prograde trajectory launches that complement those from LP-0A. SLC-20 has a legacy of hosting Titan I and IIIA rocket launches and was secured by Firefly in 2019 amid rising activity in the Eastern Range driven by NewSpace industry growth. While Firefly plans to establish an assembly facility at Cape Canaveral, current development efforts are focused on LP-0A, with the company maintaining its lease obligations at SLC-20.