Propulsion System

Introducing our Propulsion System, the HYDROS® thruster is a ‘hybrid’ electrical/chemical propulsion technology that provides truly green, safe, high-thrust, high fuel economy propulsion. HYDROS uses water as propellant, so it is safe for personnel during satellite integration and poses no significant risks to primary payloads during launch. Once on-orbit, HYDROS uses an electrolysis system designed for zero-G operation to split the water into its constituent elements, hydrogen and oxygen, for bi-propellant combustion through a rocket nozzle. It provides higher thrust efficiencies while requiring lower input power input than electric propulsion technologies and provides higher specific impulse than monopropellant chemical propulsion.

The HYDROS® thruster is a modular and scalable system. It is currently available in two flight-qualified configurations, and TUI can customize a design to your mission needs. HYDROS-M is sized for micro-satellites, and is designed to fit inside a 15″ separation ring. HYDROS-C is sized for cubesat spacecraft. The size and configuration of the water tank can be tailored to fit the mission requirements of the spacecraft. HYDROS also includes integrated avionics to greatly simplify the commanding interface and integration to the host spacecraft. 

A truly Green Propellant thruster that delivers
high-performance at a low cost

Flight Heritage!


Sized for CubeSats
Specific Impulse 
310 s
Thrust  > 1.2 N 
Power 5-25 W
Total Impulse > 2,151 Ns
Customizable water tanks

Flight Units


Sized for MicroSats
Specific Impulse 
310 s
Thrust  > 1.2 N 
Power 7-40 W
Total Impulse > 18,000 Ns
Customizable water tanks


NASA is using TUI's HYDROS®-C unit on the first Pathfinder Technology Demonstrator

Read more on the mission here

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Tethers Unlimited, Inc. | Bothell, WA | (425) 486-0100