How Tiny Water-Powered Thrusters Steer Small Satellites

A method for building microscopic water-based rocket engines that use heat to push water through tiny nozzles to steer small satellites in space.

What it covers

This patent describes a way to manufacture extremely small rocket engines, known as microthrusters, for tiny spacecraft. The device works by heating water stored in a small reservoir, which rapidly increases the pressure and forces the water out through a microscopic nozzle throat. The manufacturing process involves etching channels into layers of material—specifically silicon and borosilicate glass—and bonding them together to create the reservoir and nozzle. A key feature is the placement of a heating element that directly contacts the water and is precisely positioned relative to the nozzle throat to ensure efficient propulsion.

What it doesn't cover

• —Does not cover thrusters that use chemical propellants or combustion rather than water.
• —Does not cover thrusters with nozzle throat areas larger than 20 square micrometers.
• —Does not cover propulsion systems that do not use a heating element to create pressure.
• —Does not cover thrusters where the heating element is not in direct contact with the water.

The clever bit

The innovation lies in the extreme miniaturization of the nozzle throat (down to 6 square micrometers) combined with a specific layered manufacturing process that integrates a heating element directly into the reservoir wall to manage phase-change pressure.

Why it matters

As the space industry shifts toward CubeSats and other small satellites, there is a critical need for propulsion systems that are safe, compact, and non-toxic. Traditional satellite thrusters often use hazardous chemicals like hydrazine, which are difficult to handle. This water-based approach offers a safer, more sustainable alternative for maneuvering small spacecraft in orbit.

Real-world examples

• 1.CubeSat propulsion modules
• 2.Small satellite attitude control systems
• 3.Micro-electromechanical systems (MEMS) for space