Rocket Lab is preparing for its The Owl Spreads Its Wings mission which will launch from Launch Complex-1B, Māhia Peninsula, New Zealand. On The Owl Spreads Its Wings mission, Electron will carry a single StriX-1 satellite for the Synthetic Aperture Radar (SAR) constellation. This mission will mark the seventh launch for the company in 2022 and the third satellite delivered to space for Synspective Inc. Just like the previous The Owl’s Night Continues mission for Synspective, this one will not recover Electron’s booster.

Synspective Inc. is a Japanese Earth imaging company that is growing its synthetic aperture radar (SAR) constellation. The main objective of the company and its constellation is to deliver imagery that can detect millimeter-level changes to the Earth’s surface and does not depend on weather conditions or time of day. The SAR constellation will consist of 30 satellites by 2026 for wide-area, high-frequency Earth observation.

Once the constellation is fully built out, it is going to be used to support urban development planning, construction and infrastructure monitoring, disaster response, and other general monitoring in cities.

This is not the first time that Rocket Lab will provide launch services for Synspective Inc. The company already launched the StriX-α satellite on The Owl’s Night Begins mission in December 2020 and the StriX-β satellite on The Owl’s Night Continues mission in February 2022. The StriX satellite series derives its name from the scientific name of the owl, “Strix uralensis”.

Both the StriX-α and StriX-β are the first-generation demonstration satellites. Unlike them, the StriX-1 is the second generation and the first pre-commercial satellite of the company for full-scale business expansion. Following this satellite, the company is planning to send three more second-generation satellites into orbit by the end of 2023. This will increase the number of the StriX “owls” to six.

The StriX-α satellite was the first demonstration satellite of the company. It uses “StripMap” and “Sliding Spotlight” observation modes, providing the spacecraft with up to a one-meter resolution. StripMap has a swath of 30 km and Sliding Spotlight has a swath of 10 km; these two systems use microwaves to map out the surface of the ground to within a few millimeters. Due to the use of microwaves, the satellite can monitor the Earth’s surface during the day, night, and even during thunderstorms.

The satellite has a mass of ~150 kg and is equipped with two solar arrays and batteries for power while in orbit.

The StriX-β is the second demonstration Earth observation and radar satellite that uses X-band for precise twenty-four-hour monitoring. This test satellite has a mass of ~100 kg and is also equipped with two solar arrays and batteries.

The StriX-β was launched into a one-day recurrent Sun-synchronous orbit and can capture particular spots on the Earth at the same time and under the same conditions every 24 hours. This allows to track any changes and trends that happen at specific locations on the Earth’s surface.

Naturally, the StriX-1 satellite combines the best of its two ancestors. The satellite has a mass of ~100 kg, a ground resolution of 1-3 m, and a swath width of more than 10-30 km. Like the demonstration satellites, the StriX-1 uses the StripMap and Sliding Spotlight modes. The satellite has a 5 m SAR antenna that is stowed during launch. On the back-side of the SAR antenna, there are solar cells necessary for high power generation.

The company highlights that its satellites have a simple design, which allows cost-effective development of the constellation. Synspective’s SAR satellite technology originated from the government-led innovative R&D program, ImPACT.

Compared to the previous satellites, the second-generation ones are built in an industrialized manner and will be used for commercial data acquisition, they will be monitoring major Asian cities.

Rocket Lab’s Electron is a small-lift launch vehicle designed and developed specifically to place small satellites (CubeSats, nano-, micro-, and mini-satellites) into LEO and Sun-synchronous orbits (SSO). Electron consists of two stages with optional third stages.

Electron is about 18.5 meters (60.7 feet) in height and only 1.2 meters (3.9 feet) in diameter. It is not only small in size, but also light-weighted. The vehicle structures are made of advanced carbon fiber composites, which yields an enhanced performance of the rocket. Electron’s payload lift capacity to LEO is 300 kg (~660 lbs).

The maiden flight It’s A Test was launched on May 25, 2017, from Rocket Lab’s Launch Complex-1 (LC-1) in New Zealand. On this mission, a failure in the ground communication system occurred, which resulted in the loss of telemetry. Even though the company had to manually terminate the flight, there was no larger issue with the vehicle itself. Since then, Electron has flown a total of 29 times (26 of them were fully successful) and delivered 149 satellites into orbit.

Electron’s first stage is composed of linerless common bulkhead tanks for propellant, and an interstage, and powered by nine sea-level Rutherford engines. The second stage also consists of tanks for propellant (~2,000 kg of propellant) and is powered by a single vacuum optimized Rutherford engine. The main difference between these two variations of the Rutherford engine is that the latter has an expanded nozzle that results in improved performance in near-vacuum conditions.

For the Love At First Insight mission, the company introduced an update to the second stage by stretching it by 0.5 m. Moreover, they flew an Autonomous Flight Termination System (AFTS) for the first time.

Rutherford engines are the main propulsion source for Electron and were designed in-house, specifically for this vehicle. They are running on rocket-grade kerosene (RP-1) and liquid oxygen (LOx). There are at least two things about the Rutherford engine that make it stand out.

Firstly, all primary components of Rutherford engines are 3D printed. Main propellant valves, injector pumps, and engine chamber are all produced by electron beam melting (EBM), which is one of the variations of 3D printing. This manufacturing method is cost-effective and time-efficient, as it allows to fabricate a full engine in only 24 hours.

Rutherford is the first RP-1/LOx engine that uses electric motors and high-performance lithium polymer batteries to power its propellant pumps. These pumps are crucial components of the engine as they feed the propellants into the combustion chamber, where they ignite and produce thrust. However, the process of transporting liquid fuel and oxidizer into the chamber is not trivial. In a typical gas generator cycle engine, it requires additional fuel and complex turbomachinery just to drive those pumps. Rocket Lab decided to use battery technology instead, which allowed eliminating a lot of extra hardware without compromising the performance.

Electron has optional third stages, also known as the Kick Stage, Photon, and deep-space version of Photon. The Kick Stage is powered by a single Curie engine that can produce 120 N of thrust. Like Rutherford, it was designed in-house and is fabricated by 3D printing. Apart from the engine, the Kick Stage consists of carbon composite tanks for propellant storage and 6 reaction control thrusters.

The Kick Stage in its standard configuration serves as in-space propulsion to deploy Rocket Lab’s customers’ payloads to their designated orbits. It has re-light capability, which means that the engine can re-ignite several times to send multiple payloads into different individual orbits. A recent example includes Electron 19th mission, They Go Up So Fast, launched in in 2021. The Curie engine was ignited to circularize the orbit, before deploying a payload to 550 km. Curie then re-lighted to lower the altitude to 450 km, and the remaining payloads were successfully deployed.

Rocket Lab offers an advanced configuration of the Kick Stage, its Photon satellite bus. Photon can accommodate various payloads and function as a separate operational spacecraft supporting long-term missions. Among the features that it can provide to satellites are power, avionics, propulsion, and communications.

But there is more to it. Photon also comes as a deep-space version that will carry interplanetary missions. It is powered by a HyperCurie engine, an evolution of the Curie engine. The HyperCurie engine is electric pump-fed, so it can use solar cells to charge up the batteries in between burns. It has an extended nozzle to be more efficient than the standard Curie, and runs on some “green hypergolic fuel” that Rocket Lab has not yet disclosed.

Information about the StriX-α satellite by Trevor Sesnic

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