Tiny 3D Printed Rocket Thruster Could Democratize Nanosatellites

A study out of MIT shows the first proof of concept for a 3D printed electrospray rocket thruster, built to help nanosatellites navigate orbit. Not only is the new thruster more fuel-efficient than existing electrospray models, but its lower production cost could also make nanosatellites far less expensive to build and launch.

Nanosatellites are the lightweights of the satellite world, weighing in at 1-10 kg . The CubeSat, one of the most popular nanosatellites today, is the size of a Rubik’s Cube and weighs only 1 kg. Most of these satellites are launched aboard larger rockets, but they still need thrusters to correct their orbit once they get into space.

The CubeSat, a typical nanosatellite, is well-loved by research and education teams for its relatively-low cost (Image via the Canadian Space Agency).

The prototype showcased in the study is about the size of a dime, and puts out thrust on the order of micronewtons. It is an electrospray thruster, meaning it uses ionic liquid to generate a current of charged particles. Electrospray thrusters have two important parts: an emitting electrode that sends out the particles, and an extractor electrode that triggers it.

The researcher team made two different prototype emitters. The first one was made by binder-jetting corrosion-resistant stainless steel, and fabricated by Belgian company i.materialise. The second was vat-polymerized using FTD-IB resin and an Asiga digital light projection printer. Notably, while the industry standard for smaller thrusters is lengthy subtractive manufacturing techniques like laser machining, the current prototype was made simply with standard commercial printing services.

The prototype rocket thruster, only the size of a dime, is tiny but mighty (Image via Additive Manufacturing).

One benefit for the researchers was a quicker turnaround on the parts. Lead researcher Luis Fernando Velásquez-García said that the 3D printing process allows researchers to make designs “exquisitely iterated,” building off the results of one round of testing to improve features and explore coincidences. One such coincidence for the team was realizing that their thruster created a pure ion jet, the first from an electrospray thruster. Normally, the ions of an electrospray jet are mixed with neutral molecules. But this prototype sent out a pure ionic stream, meaning it used the propellant more efficiently. Velásquez-García believes the zinc oxide nanowires may be “the secret sauce,” and plans to test further.

Another benefit, to both the researchers and the nanosatellite-makers of the future, is the lower cost. The team who developed the CubeSat back in 1999 were specifically interested in giving university teams an affordable way to get hands-on experience exploring the stars. And with the increased role of 3D printing in launching rockets, researchers hope that the price of a ticket into space could go down even further.

“3D printing technology is … constantly improving, potentially making it possible to implement in the near future even better systems that have smaller features and are made of better materials,” said Tomasz Grzebyk, a microsystems professor quoted in MIT’s press release on the study. “We are on track to producing the best possible hardware that a lot more people can afford.”