Rocket Lab Electron
Electron is a two-stage, expendable orbital launch vehicle developed by Rocket Lab, a publicly traded aerospace manufacturer and launch service provider. Servicing the commercial small satellite launch market, it is the third most launched small-lift launch vehicle in history. Its Rutherford engines are the first electric-pump-fed engine to power an orbital-class rocket. Electron is often flown with a kickstage or Rocket Lab's Photon spacecraft. Although the rocket was designed to be expendable, Rocket Lab has recovered the first stage twice and is working towards the capability of reusing the booster. The Flight 26 booster has featured the first helicopter catch recovery attempt. Rocket Lab has, however, abandoned the idea of catching Electron.
In December 2016, Electron completed flight qualification. The first rocket was launched on 25 May 2017, reaching space but not achieving orbit due to a glitch in communication equipment on the ground. During its second flight on 21 January 2018, Electron reached orbit and deployed three CubeSats. The first commercial launch of Electron, and the third launch overall, occurred on 11 November 2018. Since then, Electron has launched successfully 77 times, with an additional 4 failures, for a grand total of 81 launches.
Design
Electron uses two stages with the same diameter filled with RP-1/LOX propellant. The main body of the rocket is constructed using a lightweight carbon composite material.Both stages use the Rutherford rocket engine, the first electric-pump-fed engine to power an orbital rocket. The electric pumps are powered by lithium-polymer batteries. The second stage uses three batteries which are "hot swapped", two of the batteries are jettisoned once depleted to shed mass. There are nine Rutherford engines on the first stage and one vacuum-optimized version on the second stage. The first stage engines deliver of thrust and the second stage delivers of thrust. Almost all of the engines' parts are 3D printed to save time and money in the manufacturing process.
Rocket Lab has also developed an optional third stage, known as the "kick stage", designed to circularize the orbits of its satellite payloads. The Electron kick stage is equipped with a single Curie engine that is capable of performing multiple burns, uses an unspecified "green" bipropellant, and is 3D printed. It was first used during Electron's second flight. The kick stage can transport up to of payload.
Rocket Lab has also developed a derivative spacecraft of the kick stage, Photon, which is intended for use on lunar and interplanetary missions. Photon will be capable of delivering small payloads of up to into lunar orbit.
The Electron payload Fairing is 2.5 m in length with a 1.2 m diameter and a total mass of 44 kg.
Production
Manufacturing the carbon composite components of the main flight structure has traditionally required 400 hours, with extensive hand labor in the process. In late 2019, Rocket Lab brought a new robotic manufacturing capability online to produce all composite parts for an Electron in just 12 hours. The robot was nicknamed "Rosie the Robot", after The Jetsons character. The process can make all the carbon fiber structures as well as handle cutting, drilling, and sanding such that the parts are ready for final assembly. The company objective as of November 2019 is to reduce the overall Electron manufacturing cycle to just seven days.Rutherford engine production makes extensive use of additive manufacturing and has since the earliest flights of Electron. This allows the capability to scale production in a relatively straightforward manner by increasing the number and capability of 3D printers.
Reusability
On 6 August 2019, Rocket Lab announced recovery and reflight plans for the first stage of Electron, although plans had started internally from late 2018. Electron was not originally designed to be a reusable launch vehicle as it is a small-lift launch vehicle but was pursued due to increased understanding of Electron's performance based on analysis of previous flights through sensors on the vehicle. In addition, reusability was pursued to meet launch demands. To counteract decreased payload capacity caused by the added mass of recovery hardware, performance improvements to Electrons are expected.Early phases of recovery included data gathering and surviving atmospheric reentry also known as "The Wall". The next phase will require a successful deployment of an aerodynamic decelerator or ballute to slow the booster followed by the deployment of parafoil concluded by a touchdown in the ocean. After a successful touchdown in the ocean, the stage would be moved onto a ship for refurbishment and reflight. Rocket Lab has not released information on aerodynamic decelerator that would be required to slow down the booster after atmospheric reentry. Late phases of Electron reuse would involve using a parafoil and mid-air retrieval by a helicopter. After a successful mid-air retrieval the helicopter would bring the Electron to a ship that would bring the stage to the launch site for refurbishment and launch. Later, Rocket Lab abandoned the plan to catch the stage with a helicopter, and will use ocean landing instead. One recovered Rutherford engine passed five full-duration hot fire tests and is declared ready to fly again. Rocket Lab's 40th Electron mission successfully reused a refurbished Rutherford engine from a previous flight.
Aerothermal decelerator
Rocket Lab, while investigating reusability, decided that they will not pursue propulsive recovery like SpaceX. Instead they will use the atmosphere to slow down the booster in what is known as "aerothermal decelerator" technology. The exact methods used are proprietary but may include keeping proper orientation when reentering the atmosphere and other technologies.Vehicle modification history
The Electron initially had a payload capacity of to a Sun-synchronous orbit.In pursuit of reusability, Rocket Lab has made changes to Electron. Flight 6 and 7 had instruments on the first stage needed to gather data to help with the reflight program. Flight 8 had Brutus, an instrument that collected data from the first stage to study reentry and was designed to be able to survive splashdown in the ocean.
Flight 10 had a block update to the first stage of the Electron to allow the first guided reentry of the first stage booster. Updates included additional hardware for guidance and navigation; onboard flight computers; and S-Band telemetry to both gather and livestream data gathered during reentry. The first stage also had a reaction control system to orient the booster. After stage separation, the first stage using the new hardware installed flipped 180° to prepare for reentry. Throughout the reentry the stage was guided though the atmosphere such that it has the right orientation and angle of attack for the base heat shield to protect the booster from destruction using RCS and onboard computers. The booster successfully survived its guided re-entry despite having no deceleration hardware onboard and destructively splashed down into the ocean at as planned if reentry was successful. Rocket Lab had no plans to recover the stage and instead wanted to demonstrate the ability to successfully reenter. Flight 11 demonstrated similar success. No further atmospheric reentry tests similar to flight 10 and 11 are expected.
Following Flight 11, in mid-February 2020, low altitude tests were done to test parachutes. In April 2020, Rocket Lab shared the successful demonstration of mid-air retrieval done in March 2020. An Electron test article was dropped by a helicopter and deployed its parachutes. A helicopter carrying a long-boom snagged a drogue line from the parachute at demonstrating a successful retrieval. Following the catch the test article was brought back to land.
Flight 16, was the first to recover the first stage booster, with a splashdown into the Pacific Ocean. The rocket also lofted thirty payloads into Sun-synchronous orbit, including a titanium mass simulator in the shape of the garden gnome "Gnome Chompski" from the video game Half-Life 2.
In August 2020, Rocket Lab announced increased payload of Electron to. The payload capacity increase was mainly due to battery advancements. The increased payload capacity allows offset of mass added by recovery technology. In addition, more payload mass could be flown on interplanetary missions and others when Electron is expended.
Fairings
Rocket Lab also announced several custom fairings, including an expanded fairing, a normal expanded fairing, an extended fairing and a dual stack fairing. The standard fairing has a usable diameter of 1.07 m while an expanded fairing has a diameter of 1.56 m. The StriX-α mission for Synspective in December 2020 used an extended fairing.Autonomous flight termination systems
Rocket Lab developed their own AFTS for launches from New Zealand from Dec 2019, but for the first launch from US they used the NASA Autonomous Flight Termination Unit.Applications
Electron is designed to launch a payload to a Sun-synchronous orbit, suitable for CubeSats and other small payloads. In October 2018, Rocket Lab opened a factory large enough to produce more than 50 rockets per year according to the company. Customers may choose to encapsulate their spacecraft in payload fairings provided by the company, which can be easily attached to the rocket shortly before launch. The starting price for delivering payloads to orbit is about US$7.5 million per launch, or US$25,000 per kg, which offers the only dedicated service at this price point.Moon Express contracted Rocket Lab to launch lunar landers on an Electron to compete for the Google Lunar X Prize. None of the contenders met the prize deadline, and the competition was closed without a winner. For sometime after the closure of GLXP, the Moon Express Electron launches remained scheduled, but before February 2020, all the launches of Moon Express using Electron were canceled.