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| Function | Medium-lift launch vehicle | ||||||||||||||||||||||
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| Manufacturer | Rocket Lab | ||||||||||||||||||||||
| Country of origin | United States | ||||||||||||||||||||||
| Cost per launch | $50 million[1] | ||||||||||||||||||||||
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| Comparable | Falcon 9 | ||||||||||||||||||||||
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| Status | In development | ||||||||||||||||||||||
| Launch sites | MARS,LC-3 | ||||||||||||||||||||||
| First flight | 2026 (planned) | ||||||||||||||||||||||
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Neutron is apartially reusable,medium-lift,two-stage launch vehicle under development byRocket Lab. Announced on March 1, 2021, the vehicle is designed to be capable of delivering a payload of 13,000 kg (28,700 lb) tolow Earth orbit in apartially reusable configuration,[2] and will focus on the growingmegaconstellationsatellite delivery market.[3] First launch is expected after the first quarter of 2026.[4]
![[icon]](/mt/?noimg=&dark=on&url=https%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aWiki_letter_w_cropped.svg) | This sectionneeds expansion with: a description of the rocket design now, in 2025, separated from the extensive "Design history" where various changes have occurred over 4+ years. You can help byadding to it.(July 2025) |
An earlier design of Neutron (March 2021), included a rocket 40 m (130 ft) tall with a 4.5 m (15 ft)-diameterpayload fairing. Rocket Lab stated that they intended for thefirst stage of the vehicle to bereusable, with landings planned on afloating landing platform downrange in theAtlantic Ocean.[3][5]
On December 2, 2021, Rocket Lab unveiled a revised design for Neutron, featuring a tapered shape with a maximum diameter of 7 m (23 ft).[2] Rocket Lab abandoned opts for a return-to-launch-site reusability profile and on afloating platform. Instead of a conventionalpayload fairing that is jettisoned and recovered at sea, the fairing is integrated into the vehicle, and opens during stage separation to release the second stage and payload, and then closes before the first stage lands back on earth. The rocket features a unique interstage design where the second stage is "hung" from the first stage structure.[6]
On September 22, 2022, another revised design was unveiled at an investor day, with the first stage engine count increased from seven to nine, and the engine architecture changed fromgas-generator to oxygen richstaged combustion. This was done primarily to allow for a lower turbine temperature, while maintaining the samespecific impulse. The engine will run with a significantly lower chamber pressure than other similar engines, at the cost of some performance. The number of fairing segments was reduced from four to two.[7]
On July 27, 2023, new concept art on the Rocket Lab website showed a further revised design, with a reduction in the number ofpayload fairing sections from 4 to 2, redesignedlanding legs, and small changes to the overall shape of the rocket. The number of payload fairing sections was reduced in order to allow for simpler fairing opening mechanisms while the landing legs were redesigned in order to be optimized for landings onfloating platforms, allowing for an increase in launch availability. The redesigned legs feature a folding mechanism similar to theSpaceX Falcon 9 landing legs.[8][9]
During the company's earnings call in February 2025, a plan to modify the offshore bargeOceanus were unveiled. Whenmodifications are complete, the ship will be namedReturn On Investment.[10] The 120 m (400 ft) ship will be refit byBollinger Ship in Louisiana.[11]
On February 28, 2022, Rocket Lab announced that Neutron will launch from theMid-Atlantic Regional Spaceport (MARS) withinNASA'sWallops Flight Facility on the eastern coast ofVirginia.[6][12][13] It was also announced that the company will build a 250,000 square feet manufacturing and operations facility adjacent to the Wallops Flight Facility.[13] Ground was broken for this facility on April 11, 2022.[14] As of December 2021[update], Rocket Lab is planning for the first launch to take place no earlier than July 2025.[6] Test firing of Neutron'sArchimedes engine occurred at NASA'sStennis Space Center inHancock County, Mississippi.[15]
In September 2025, Rocket Lab held a ceremony to mark the launch pad (including deluge system) being ready for launch.[16]
Past and future development milestones for Neutron.[17]
| Date | Milestone | Status |
|---|---|---|
| Q2 2022 | Moulds and tooling for Neutron completed | Completed[18] |
| Q3 2022 | Full-scale prototype hardware for Archimedes and Neutron being made | Completed[19] |
| Nov 4, 2022 | Opening Archimedes test complex at NASA Stennis Space Center | Completed[20] |
| Q4 2022 | Pre-burner hotfire Test of Archimedes engine for the first time | Completed[21] |
| Jan 10, 2023 | Testing engine ignition on development hardware | Completed[22] |
| Q1 2023 | Test stand infrastructure completed for Neutron Stage 2 tank | Completed[23] |
| Aug 8, 2023 | First Stage 2 build | Completed[24] |
| Oct 4, 2023 | Stage two structural and cryogenic testing | Completed[25] |
| May 6, 2024 | First Archimedes development engine built | Completed[26] |
| Aug 8, 2024 | First Archimedes engine hot fire | Completed[27] |
| 2024 | Testing of all avionics and communications devices with critical onboard software and GNC algorithms | Completed[28] |
| NET 2024 | Flight mechanisms test program | In progress |
| NET 2025 | Stage 1 build | In progress |
| NET 2025 | Stage 2 static fire | In progress[29] |
| NET 2025 | Stage 1 static fire | Not started |
| Q3 2025 | Launch Complex 3 complete | Completed[29] |
| NET 2025 | Final integration | In progress[29] |
| Q1 2026 | Delivery to Launch Complex 3 for qualification testing and acceptance | Not started[4] |
| NET 2026 | Launch | Not started[4] |
Neutron is designed to lift up to 15,000 kg (33,100 lb) while expended, 13,000 kg (28,700 lb) while landing the booster downrange and up to 8,500 kg (18,700 lb) with the first stage returning to the launch site.[30] Rocket Lab forecasts Neutron will be able to launch 98% of all payloads launched through 2029. Rocket Lab also intends thedesign to be able to supportconstellation deployment,deep space missions, and eventuallyhuman spaceflight.[5]
In May 2025, Rocket Lab was awarded an evaluation contract to test for compatibility of Neutron with the USAFRocket Cargo program for return-to-Earth cargo delivery anywhere on Earth.[31]
The first flight of Neutron is expected to be in mid 2026.[32]
In September 2025, Rocket Lab planned to launch Neutron three times in 2026, and five times in 2027.[16]
According to Rocket Lab, Neutron’s expected debut launch in 2025 also puts the launch vehicle in a strong position to on-ramp onto the U.S. Government’sNational Security Space Launch (NSSL) Lane 1 program, an indefinite delivery indefinite quantity (IDIQ) contract valued at $5.6 billion over a five-year period. RFPs for the program opened on October 30, 2024 with approved new launch vehicles to be on-ramped to the program in Spring 2025.
In November 2024 Rocket Lab announced that it has signed a multi-launch agreement with a confidentialcommercial satellite constellation operator to launch asatellite constellation using Neutron. Under the contract, Rocket Lab will launch two dedicated missions on Neutron starting from mid-2026. The missions will launch fromRocket Lab Launch Complex 3 onWallops Island, Virginia. The launch service agreement for these missions signifies the beginning of a productive collaboration that could see Neutron deploy the entire constellation.[33]
Updating our Neutron schedule that has the rocket arriving at Rocket Lab Launch Complex 3 in Q1, 2026, with the first launch thereafter, pending the successful completion of the vehicle's qualification testing and acceptance program.
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