The functionality of any space mission is determined by its electrical, electronic and electro-mechanical (EEE) components.
Individually small in size, a standard satellite can contain thousands of active and passive devices, along with several kilometres of connective links ESA is looking into printing these electronics, to boost overall robustness while driving down mass, manufacturing lead times, and cost.
Printed electronics involves 3D printing a variety of electrically active materials such as metals or carbon-doped polymers to form devices like transistors, capacitors and resistors, plus the electrical connectors linking them together.
“Printed and flexible EEE components are fast rewriting the future of electronics,” explains ESA Internal Research Fellow Rita Palumbo, overseeing a new working group on the topic. “So we are looking into how space could benefit from this step change.”
Dr Palumbo’s multidisciplinary working group spans multiple ESA sites and brings together experts from different areas of expertise, such as materials, components, antennas and microwave payloads, spanning four ESA Directorates – Earth Observation; Human and Robotic Engineering; Technology, Engineering and Quality; and Telecommunications and Integrated Applications – with the goal of creating a shared roadmap for the introduction of printed electronics to the space sector.
Printed EEE parts have the major advantage of flexibility, being able to be printed in virtually any shape, with flexible substrates laid down along complex geometries, in ways that would be next to impossible with traditional manufacturing.
They can also be produced at much lower cost – on the order of 95% cheaper than standard EEE parts according to tech giant Mercury Systems – and done so locally, without the need to manufacture parts around the world in Asian fab plants, and compatibly with the low-volume high-variety mix requirements of space industry. This also considerably reduces the turnaround time – from 3-4 months to 12 hours.
In addition, materials cheaper than those usually employed in the traditional silicon microelectronics industry can be harnessed, such as electrically active polyester or PEEK plastic. The circuits are printed onto thin substrates and can be printed on existing hardware or structural surfaces. Utilising 3D printing opens up a new design dimension, allowing the creation of novel stacked or embedded integrated circuits.
Traditionally, soldering links represent a major point of potential failure for EEE parts – so much so that ESA organises a network of soldering schools across Europe. Fragile solders or silicon connections can instead be replaced with ‘ink stacks’ which are much stronger mechanically, better able to survive the stresses of launch.
Also, 3D printing opens the prospect of in-situ repair and production of parts in locations such as the International Space Station, the Moon, or Mars.
“Finally, printed electronics present a much more sustainable approach in terms of production, looking forward to a future where sustainability becomes a regulatory requirement,” adds Dr Palumbo. “They can be produced with 65-80% less waste, less manufacturing tooling and at lower temperatures, with a far reduced carbon footprint in terms of transportation, and utilising recycled and bio-based plastics as well as potentially recycled silver.”
The main drawback is that printed electronics do not yet possess the extreme accuracy and resolution capability of common fabrication methods used in the silicon microelectronics industry.
Another issue is that compatibility with the space environment is also not fully established, except in a few cases. For example, Redwire has provided NASA with Roll-Out Solar Arrays (ROSA), fully flexible and deployable solar arrays being used on the International Space Station, aboard the DART mission that last year impacted the Dimorphos asteroid, and will be adopted for the Power and Propulsion element on the Gateway station around the Moon.
And recently, Space Foundry has developed a breakthrough Plasma Jet Printing technology at NASA Ames Research Center (ARC), successfully tested in microgravity, while researchers at Iowa State University worked with NASA to test 3D printing electronics in weightless conditions.
“Printed electronics is not intended to compete with but rather complement the traditional silicon electronics industry,” explains Dr Palumbo. “The most promising direction is actually ‘Hybrid Printing’, combining printed substrates and functional inks with traditional components to get the best of both worlds.”
Combining experts from disparate fields, ESA’s working group is currently researching all possible applications of the technology for space, before narrowing them down to a few game-changing directions compatible with space requirements to prioritise investment.
