CURIE

Curie is a compact liquid-propellant rocket engine designed and manufactured by Rocket Lab, the space company responsible for the Electron small-launch vehicle and Photon spacecraft platform. It is used primarily to provide in-space propulsion after an Electron launch vehicle has deployed its principal payload. In this role, Curie powers the Electron third stage, commonly called the kick stage, allowing a satellite to be released into an orbit that differs from the initial deployment orbit or to be positioned more precisely for its mission. The engine is also associated with Rocket Lab’s Photon spacecraft, where an integrated propulsion system supports maneuvering and mission operations in orbit. The engine was created for a segment of the launch market in which small satellites often need more orbital flexibility than a conventional launch vehicle can provide by itself. Rocket Lab describes the kick-stage concept as a way to free small spacecraft from the constraints of the primary payload orbit. This can enable faster deployment of satellite constellations, more suitable positioning for Earth-observation missions, and other orbital adjustments without requiring every spacecraft to carry a large propulsion system. Curie is a small, three-dimensionally printed engine. The engine’s propellant composition has not been publicly disclosed and is treated by Rocket Lab as a trade secret. Reference material identifies the bipropellant configuration used by the Electron kick stage as producing approximately 120 newtons of thrust, with a specific impulse of about 320 seconds. The kick stage is more than an engine alone: it carries its own avionics, power, communications, and reaction-control equipment, making it a self-contained orbital transfer stage. The first in-space use of Curie occurred during Rocket Lab’s first successful orbital launch on 21 January 2018. After the Electron upper stage deployed its payloads, the kick stage coasted for roughly 40 minutes before firing the engine in space. The mission demonstrated the ability to perform a post-deployment orbital maneuver and supported the release of small satellites, including Lemur-2 spacecraft built by Spire Global. The stage used on that early demonstration was left in orbit, while Rocket Lab subsequently stated that future versions would be deorbited after completing their payload-delivery duties to reduce the creation of additional orbital debris. Rocket Lab has also developed HyperCurie, a higher-thrust derivative. Unlike the pressure-fed Curie configuration, HyperCurie uses electric pump-fed propulsion. It was used on NASA’s CAPSTONE lunar mission, launched in June 2022, and has been identified for use on Rocket Lab’s planned Venus Life Finder Photon mission. This extended the Curie family from Earth-orbit payload deployment into deep-space and planetary mission applications. Curie is therefore best understood not as a consumer brand, but as a Rocket Lab propulsion product and spacecraft-transport technology. Its positioning rests on compactness, additive manufacturing, orbital precision, and integration with a flexible kick-stage architecture. Public information does not establish a separate corporate entity, standalone commercial pricing, or an independent sales channel for the engine.

Curie was developed by Rocket Lab as a compact in-space propulsion system for the company’s Electron launch architecture. The design addresses a specific limitation of small-launch missions: the primary payload may be delivered successfully but still require a different orbit, additional separation points, or more accurate positioning than the launch vehicle’s main ascent can provide. Rocket Lab therefore incorporated a powered third stage, or kick stage, capable of operating independently after the principal payload deployment. The engine is named after Polish scientist Marie Skłodowska-Curie. It is described as a small liquid-propellant engine and is manufactured using three-dimensional printing. Its propellant chemistry has not been publicly revealed. The Electron kick stage uses its own avionics, electrical power, communications equipment, and reaction-control system alongside the Curie engine, allowing the stage to operate as a self-contained orbital-transfer vehicle rather than merely as a conventional upper-stage extension. Curie first flew in space during Rocket Lab’s first successful orbital launch on 21 January 2018. Following the deployment sequence, the kick stage remained in orbit for approximately 40 minutes before firing Curie for its first in-space test. The demonstration showed how a small launch vehicle could provide post-deployment orbital services, including the ability to release satellites into more suitable trajectories. The mission carried small spacecraft including Lemur-2 satellites built by Spire Global. The early stage was left in orbit after its demonstration, but Rocket Lab stated that later mission designs would deorbit the stage after payload delivery to limit the accumulation of space debris. Public descriptions identify the original or standard kick-stage engine as pressure-fed and report approximately 120 newtons of thrust and a specific impulse of about 320 seconds. Rocket Lab has also discussed a liquid bipropellant configuration while retaining the exact propellant formulation as confidential. Earlier Rocket Lab work demonstrated a non-toxic viscous liquid monopropellant concept, but publicly available reference material does not establish that this was the final operational Curie propellant. Rocket Lab subsequently developed HyperCurie, a more powerful member of the same general propulsion family. HyperCurie differs technically from Curie by using an electric pump-fed architecture rather than pressure feed. Its use on NASA’s CAPSTONE lunar mission, launched in June 2022, demonstrated that Rocket Lab’s propulsion approach could support missions beyond low Earth orbit. Rocket Lab has also identified HyperCurie for the Photon spacecraft planned for the Venus Life Finder mission. The Curie family’s significance lies in its integration with Rocket Lab’s broader launch-and-spacecraft strategy. Instead of treating launch as ending at the first payload separation, the kick stage provides an additional orbital service that can improve deployment flexibility for small satellites. The engine’s compact scale, additive-manufacturing approach, and adaptation to both Earth-orbit and deep-space missions support Rocket Lab’s positioning in the small-launch and spacecraft-services markets. Public sources do not provide a standalone founding date, independent ownership structure, pricing model, or separate corporate headquarters for Curie; these attributes belong to Rocket Lab rather than to the engine as a distinct company.

• 2022

  HyperCurie used for CAPSTONE

  [1]Curie (rocket engine)en.wikipedia.org

  The higher-thrust, electric pump-fed HyperCurie variant was used on NASA’s CAPSTONE lunar mission.

• 2020

  Bipropellant configuration publicly identified

  [1]Curie (rocket engine)en.wikipedia.org

  Rocket Lab indicated that the kick stage used a liquid bipropellant configuration, without disclosing the formulation.

• 2018

  First in-space Curie test

  [1]Curie (rocket engine)en.wikipedia.org

  Curie was fired by the Electron kick stage during Rocket Lab’s first successful orbital launch on 21 January, demonstrating post-deployment orbital maneuvering.

Compact, additively manufactured in-space propulsion for precise small-satellite deployment and spacecraft maneuvering.

• Liquid-propellant orbital-transfer engine · 2018

  Curie

  A compact, three-dimensionally printed liquid-propellant rocket engine developed by Rocket Lab. It powers the Electron kick stage and can also support Photon spacecraft missions. The pressure-fed engine is reported to produce approximately 120 newtons of thrust with a specific impulse of about 320 seconds. Its undisclosed propellant chemistry is treated as a Rocket Lab trade secret. Curie enables post-deployment orbit changes and more accurate placement of small satellites.

• Higher-thrust liquid-propellant rocket engine · 2022

  HyperCurie

  A higher-thrust development of the Curie propulsion family. HyperCurie uses electric pump feed rather than the pressure-fed architecture associated with Curie. It was used on NASA’s CAPSTONE lunar mission and has been identified for a planned Photon mission to Venus, demonstrating an intended role in lunar and planetary spacecraft operations.

• 2022

  Extension of the Curie family through HyperCurieGeneration change

  Background

  Rocket Lab required propulsion suitable for missions beyond routine Earth-orbit satellite deployment.

  Action taken

  Rocket Lab developed the higher-thrust, electric pump-fed HyperCurie variant and used it on NASA’s CAPSTONE lunar mission.

  Aftermath

  The mission expanded the demonstrated application of the Curie family into lunar operations, with a future Venus mission identified as another intended application.

  Source

• 2018

  Demonstration of Curie-powered post-deployment maneuveringProduct launch

  Background

  Small satellites can require orbital destinations different from the primary launch trajectory. Rocket Lab developed the Electron kick stage to provide propulsion after the main payload deployment.

  Action taken

  Rocket Lab ignited Curie during the first successful Electron orbital mission after the kick stage had coasted for roughly 40 minutes.

  Aftermath

  The test demonstrated an orbital-transfer capability for small payloads. Rocket Lab later stated that future kick stages would be deorbited after completing their missions to reduce orbital debris.

  Source

1. 1Curie (rocket engine)en.wikipedia.org