CHIBA, JAPAN, September 10, 2025 – Pale Blue Inc. successfully operated the world’s first Water Ion Thruster in orbit.

Water Ion Thruster (PBI)

 

Pale Blue confirmed the world’s first successful in-orbit operation of PBI, a water ion thruster optimized for small satellites. This marks the world’s first operation in space of an ion engine using water as the propellant. With a mass production system already in place, our proprietary PBI is now being delivered to partners worldwide.

 

【Key Features of PBI】

Superior Performance and Versatile Mission Capabilities:

Despite its compact, palm-sized 1U+ (approximately 10 cm cube) form factor, the thruster delivers a high total impulse*, contributing to various missions including orbit maintenance. The thruster can also be clusterized, enabling multiple units to work together to accommodate a wider range of spacecraft sizes and diverse mission requirements

 

High-Efficiency Operation with Rapid Start-Up:

The thruster’s short warm-up time to injection enables immediate, on-demand ignition. This minimizes service interruptions during satellite operations and dramatically improves mission efficiency.

 

Combined Safety and Cost Efficiency:

Using water as the propellant with its safe and easy to handle properties simplifies the supply chain, significantly reducing total costs from development through operation.

 

*A key performance metric for a propulsion system. It represents the total change in momentum that a thruster can produce over its entire firing duration, until all of its propellant is expended.

 

Comment from Jun Asakawa, Co-Founder and CEO of Pale Blue

We are proud to announce the successful in-orbit operation of the PBI Water Ion Thruster, marking a major milestone in our company’s history. PBI is a one-of-a-kind propulsion system that uses water as the propellant, offering a safe, easily handled, and readily available alternative to conventional propellants. The system delivers high performance despite its incredibly compact size of approximately 10 cm cube. I am confident that this product and technology will expand the possibilities of future space development and satellite applications. I extend my sincerest gratitude to everyone who has supported us on this journey and am incredibly proud of the Pale Blue team for their dedication in transforming the PBI into a tangible solution.

 

 

About Oral Presentations at IEPC

At the International Electric Propulsion Conference (IEPC), the world’s largest conference in the field of electric propulsion, our co-founder and director, Dr. Nakagawa, will give three oral presentations, including the demonstration of the Water Ion Thruster.

September 14 to 19, 2025

At Imperial College London

 

 

About Water Ion thruster (PBI) in-orbit demonstrations

“Pale Blue to test the world-first 1U+ Water Ion Thruster in orbit with D-Orbit” (January 8, 2025）

https://pale-blue.co.jp/news/543/

 

 

About Pale Blue

Pale Blue develops and manufactures propulsion systems (engines) for small satellites, serving satellite integrators and operators worldwide. Since its founding in 2020, Pale Blue has successfully achieved in-orbit operations of water-based propulsion systems a number of times, providing highly reliable solutions. While further expanding its product offering through R&D and in-orbit demonstrations, Pale Blue is also strengthening production capabilities to meet the growing demand for propulsion systems. Pale Blue is committed to creating mobility that is core to the space industry, driving the next generation of space development.

Website：https://pale-blue.co.jp/

 

 

Contact

pr@pale-blue.co.jp