You Can’t Take It with You
Future astronauts may 3D print their own propulsion systems in space thanks to a new technique developed at MIT.
One of the biggest challenges we have to contend with in space exploration is the fact that astronauts need to take everything that they might possibly need with them from the get-go. There are (so far as we know) no hardware stores or 7-Elevens out there to pick up snacks and supplies. For a lengthy mission — like to Mars — that means the crew will need a whole lot of supplies to sustain them for the months-long trip there and back. However, the cost of getting a payload into space is exorbitant, and there is only just so much capacity.
As such, the line has to be drawn somewhere. Another backup system might save a crew that finds itself in a tough spot, but if it prevents them from bringing enough food, it is not going to make it onboard. A pair of MIT researchers showed that this difficult trade-off may soon be a thing of the past — at least to some extent. Their work demonstrates that 3D printing can be used to produce important items on demand. And this is not just the simplest of necessities; the team developed a method to produce electrospray thrusters with 3D printing technology.
Electrospray thrusters are an advanced form of space propulsion that work by applying an electric field to a conductive liquid, producing a high-speed jet of charged droplets that generate thrust. These engines are ideal for small satellites like CubeSats, which are frequently used for research and commercial applications. Unlike chemical rockets, electrospray thrusters use fuel more efficiently, making them well-suited for precise in-orbit maneuvers.
However, manufacturing these thrusters has traditionally been a costly and time-consuming process that requires semiconductor cleanroom fabrication. But the team showed that these thrusters can be produced more rapidly and at a fraction of the cost using commercially available 3D printing techniques. Even more impressively, this technology could enable astronauts to print replacement parts — or even entire propulsion systems — while in space.
The 3D-printed thruster consists of three main components: a manifold block that stores and distributes propellant, emitter modules that generate thrust, and an extractor electrode that applies voltage to eject the charged droplets. The device features an array of 32 electrospray emitters, all operating in parallel to produce a stable and uniform flow of propellant.
To successfully 3D print the thruster, the researchers used two different types of vat photopolymerization printing. The first, two-photon polymerization, allowed them to print microscopic components like the emitters with extreme precision. The second, digital light processing, was used to fabricate larger parts, such as the manifold block, which connects and supplies the emitters with fuel. By combining these two methods, the team was able to overcome the challenges of integrating macroscale and microscale components into a single, functional device.
In testing, the 3D-printed thruster not only matched but, in some cases, outperformed conventional electrospray engines. The team also discovered a key advantage in how thrust is controlled. While traditional electrospray engines rely on complex pressure systems to regulate fuel flow, it was found that adjusting the voltage applied to the emitters provided a wider range of control. This voltage-based modulation simplifies the system, reducing the need for additional hardware and making the thruster even more efficient.
By reducing dependence on pre-manufactured components and allowing for on-demand fabrication, this technology could make space missions more flexible, cost-effective, and sustainable in the long run.