3D-printed electrospray engines could change satellite propulsion

Researchers at the Massachusetts Institute of Technology (MIT) have developed a fully 3D-printed electrospray engine specifically designed for use in small satellites known as CubeSats. This technology could provide a more cost-effective and flexible alternative to conventional satellite propulsion systems and is also potentially suitable for additive manufacturing in space.

An electrospray thruster uses an electric field to break up conductive liquids into fine, highly accelerated droplets that are used to generate thrust. This propulsion system offers greater efficiency in propellant utilization than chemical rocket engines and is therefore particularly suitable for precise orbit corrections in orbit. The challenge with conventional electrospray thrusters, however, lies in the complex manufacturing process using clean room procedures, which limits the spread of this technology.

“Using semiconductor manufacturing doesn’t match up with the idea of low-cost access to space. We want to democratize space hardware. In this work, we are proposing a way to make high-performance hardware with manufacturing techniques that are available to more players,” says Luis Fernando Velásquez-García, a principal research scientist in MIT’s Microsystems Technology Laboratories (MTL) and senior author of a paper describing the thrusters, which appears in Advanced Science.

The MIT team optimized this process by using two different 3D printing technologies. The fine emitter modules that spray the propellant were produced using two-photon lithography, which produces extremely sharp tips and uniform capillaries for the propellant flow. In contrast, the larger manifold block that holds the modules in place and supplies them with propellant was printed using digital light processing, a technique that efficiently produces larger structures.

“Using a one-size-fits-all fabrication approach doesn’t work because these subsystems are at different scales. Our key insight was to blend additive manufacturing methods to achieve the desired outcomes, then come up with a way to interface everything so the parts work together as efficiently as possible,” Velásquez-García says.

The developed engine contains 32 spray emitters that are operated together and generate a uniform thrust. Tests showed that the 3D-printed variant offers comparable or even better performance than existing electrospray thrusters. In addition, by varying the electrical voltage, the researchers were able to adjust the thrust without complex valve systems, further simplifying the design.

In the future, the researchers want to expand the concept and realize a higher density of emitters. In the long term, a CubeSat will demonstrate how a fully 3D-printed electrospray thruster works in orbit. The work was funded by a grant from MathWorks and the NewSat project, among others.