MIT Researchers Create Entirely 3D-Printed Electrospray Engine from Scratch: A breakthrough in space propulsion technology, the fully 3D-printed engine is ideal for propelling tiny satellites and could revolutionize the field of space exploration.
MIT Engineers Develop a Fully 3D-Printed Electrospray Engine
Ideal for Propelling Tiny Satellites
MIT engineers have demonstrated the first fully 3D-printed, droplet-emitting electrospray engine. This lightweight device could be produced on board a spacecraft and costs much less than traditional thrusters.
Electrospray engines produce thrust by shooting out a stream of highly charged droplets. The MIT researchers used a precise fabrication method that enhances the electrohydrodynamic reaction that generates these droplets.
The device requires a complex hydraulic system to store and regulate the flow of liquid, efficiently shuttling propellant through microfluidic channels to a series of emitters.
A Modular Approach
An electrospray engine has a reservoir of propellant that flows through microfluidic channels to a series of emitters. An electrostatic field is applied at the tip of each emitter, triggering an electrohydrodynamic effect that shapes the free surface of the liquid into a cone-shaped meniscus that ejects a stream of high-speed charged droplets from its apex, producing thrust.
An electrospray engine is a type of propulsion system used in spacecraft and satellites.
It works by ionizing and accelerating charged particles, such as xenon gas, to generate thrust.
This technology offers high efficiency and specific impulse, making it suitable for long-duration missions.
Electrospray engines are also relatively lightweight and compact, allowing them to be integrated into smaller spacecraft designs.
The emitter tips need to be as sharp as possible to attain the electrohydrodynamic ejection of propellant at a low voltage. The device also requires a complex hydraulic system to store and regulate the flow of liquid, efficiently shuttling propellant through microfluidic channels.
Overcoming Challenges
To overcome the challenges involved in fabricating a complex device comprised of macroscale and microscale components that must work together seamlessly, the researchers utilized two different types of vat photo polymerization printing (VPP). VPP involves shining light onto a photosensitive resin, which solidifies to form 3D structures with smooth, high-resolution features.
The researchers fabricated the emitter modules using a VPP method called two-photon printing. This technique utilizes a highly focused laser beam to solidify resin in a precisely defined area, building a 3D structure one tiny brick, or voxel, at a time. This level of detail enabled them to produce extremely sharp emitter tips and narrow, uniform capillaries to carry propellant.
Propelling Performance
The researchers also conducted chemical experiments to ensure the printing materials were compatible with the conductive liquid propellant. If not, the propellant might corrode the engine or cause it to crack, which is undesirable for hardware meant for long-term operation with little to no maintenance.
A propellant is a substance used to generate thrust in a vehicle, such as a rocket.
The most common types of propellants are liquid fuels and oxidizers.
Liquid hydrogen and liquid oxygen are commonly used in spacecraft due to their high specific impulse and efficiency.
Solid propellants, on the other hand, consist of a mixture of fuel and oxidizer that burn rapidly when ignited.
Historically, gunpowder was one of the first propellants used in firearms.
The development of modern propellants has been driven by advances in materials science and chemistry.
They also developed a method to clamp the separate parts together in a way that avoids misalignments which could hamper performance and ensures the device remains watertight. In the end, their 3D-printed prototype was able to generate thrust more efficiently than larger, more expensive chemical rockets and outperformed existing droplet electrospray engines.
Future Work
The researchers want to continue exploring the benefits of voltage modulation in future work. They also want to fabricate denser and larger arrays of emitter modules. In addition, they may explore the use of multiple electrodes to decouple the process of triggering of the electrohydrodynamic ejection of propellant from setting up the shape and speed of the emitted jet.
In the long run, they also hope to demonstrate a CubeSat that utilizes a fully 3D-printed electrospray engine during its operation and deorbiting. This research is funded, in part, by a MathWorks fellowship and the NewSat Project, and was carried out, in part, using MIT.nano facilities.
