A close-up look at the first metal part made in space

With future missions venturing deeper into space, in-orbit manufacturing will become essential. Tailoring existing 3D printing methods to reliably function in microgravity will allow astronauts to manufacture tools or replacement parts for repairs without depending on costly resupply missions.

In January 2024, ESA launched the first metal 3D printer to the International Space Station (ISS). This technology demonstrator was developed by an Airbus-led industrial team and installed in the ISS Columbus module by ESA astronaut Andreas Mogensen. Only a few months after installation, the device created a 2D single-layer track in the shape of an ‘S’ during calibration.

Space metal brought down to Earth

Producing these simple 2D shapes prepared the demonstrator for the printing of its very first complete sample, which has since travelled from the ISS all the way to ESTEC, ESA’s technical heart in the Netherlands.

Here, materials engineers are busy examining, cutting and bending the piece of space metal to understand if and how microgravity affected the printing process.

“We are comparing this metal part with an identically shaped one created here on Earth, using the same printer before it was shipped to the ISS,” explains Caterina Iantaffi, ESA’s materials engineer. “What we are looking for are differences attributable to different gravity levels. This will also help us learn how a metal 3D printer in space should be operated.”

Rob Postema, ESA’s technical officer of the project, recounts the unboxing moment: “When the first printed sample arrived at ESTEC and we carefully removed it from the transport container and protective packaging, it felt like we were unpacking a Christmas present. It was a wonderful and exciting experience to open the box and find a very well-printed first sample that has come all the way from the International Space Station, and to ensure it was properly handed over to ESTEC engineers for post-processing.”

Printing the future layer by layer

Both metal parts were 3D-printed using Laser-Wire Directed Energy Deposition, a common and well-studied additive manufacturing technique.

“In this technique, a near-infrared laser serves as a localised heat source that melts a stainless-steel substrate and wire,” says Caterina. “By focusing the laser on a small spot, a ‘melt pool’ of material is formed. The metal wire is continuously fed into this pool, where it melts.

“As the wire and laser move relative to the substrate, the molten material behind the laser beam solidifies. By following a programmed path, the process builds up the part, layer by layer, into the desired shape.”

A peek inside

Caterina’s inspection of the first metal made in space began at a microscope – this first look through a magnifying lens allowed her to see any ridges and imperfections on the surface of the metal more clearly.

The next step was a CT scan, during which the metal sample rotated in a machine while being scanned using X-rays. This thorough examination resulted in a 3D digital model revealing the inside of the sample, allowing the researchers to identify the size and location of any pores (air bubbles).

Stretched, bent and snapped

In a process called machining, the individual parts that make up the full metal sample – three larger, dog-bone-shaped ones and three smaller cylindrical ones – were separated from the base, and their ‘skin’ was removed, leaving them with a very smooth surface.

Each of the three larger samples was sprayed with paint to create a fine randomised speckle pattern on its surface. This pattern was scanned as the testing machine gripped each end of the sample and pulled until it snapped.

Caterina explains: “As the sample was being stretched, the speckle pattern deformed accordingly, allowing us to assess the strain of the material. The smaller samples were tested in a similar way, but by bending instead of stretching.”

First of a kind

“We will now take a close look at the data generated from testing the sample and compare it with the sample printed on Earth,” Caterina comments. “In the coming months, we will publish our findings to share them with the wider scientific community.”

“For a materials engineer, getting to inspect the very first metal object 3D-printed in space is both thrilling and inspiring,” she adds. “It is a truly remarkable milestone for the additive manufacturing field, and I am grateful to have played a small part alongside many talented colleagues.”

Rob concludes: “We will use the lessons we learn from this first initiative to design a printer which could be used to provide spare parts for actual use. For this, we will not only look at improving the printer and its performance but also consider the pre-processing of stock materials and post-processing of the printed sample.”

Advenit Makaya, ESA’s advanced manufacturing engineer supporting the project, adds: “This first metal part is the achievement of a great collaboration. It is also one more step towards a future where manufacturing in space will be an integral part of sustainable space activities – where what we need, from tools to large spacecraft structures, can be made, repaired and recycled directly when we need it.”