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.
Original patent title: “Tunable water-based microthruster devices and methods”
A method for building microscopic water-based rocket engines that use heat to push water through tiny nozzles to steer small satellites in space. Granted to Purdue Research Foundation in 2024 with 24 claims.
Key facts
Coverage
What does this patent actually cover?
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.
The gap
What does this patent NOT 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.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
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.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
CubeSat propulsion modules
Small satellite attitude control systems
Micro-electromechanical systems (MEMS) for space
Why it matters
The bigger picture
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.
Filed
September 7, 2021
Granted
January 23, 2024
Market context
Who's building on this
Companies in this space
Purdue University researchers are the primary drivers of this technology. The broader field of MEMS-based propulsion is being explored by various aerospace startups and university labs focused on miniaturized satellite components, as the industry moves away from toxic propellants.
Market impact
This patent provides a foundation for a new class of 'green' propulsion systems for the rapidly growing small satellite market. By enabling low-cost, batch-manufactured thrusters, it helps lower the barrier to entry for small-scale orbital maneuvering and station-keeping.
Claim 1 — Plain English
What this patent 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.
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.
What it does not 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.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Early stage
Citation count
0/40
No citations yet
Claim breadth
16/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
20/20
Granted within 5 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$21K – $67K
Midpoint $42K · 15.2 yr remaining · industry ×0.9
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
24 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Pugia, S. M., Alexeenko, A., & Cofer, A. G. (2024). How Tiny Water-Powered Thrusters Steer Small Satellites (U.S. Patent No. 11,878,818). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/11878818/starlink-maritime
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Tiny Water-Powered Thrusters Steer Small Satellites cover?
A method for building microscopic water-based rocket engines that use heat to push water through tiny nozzles to steer small satellites in space.
Who owns patent US 11878818?
Purdue Research Foundation owns this patent, granted in 2024.
When does this patent expire?
This patent is expected to expire on January 23, 2044, when the invention enters the public domain.
What problem does this patent solve?
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.
What does this patent NOT cover?
Does not cover thrusters that use chemical propellants or combustion rather than water.
Patent monitoring