For the first time, a metal part printed in the International Space Station (ISS) has been sent back to Earth. ESTEC will examine the part, with the aim of better understanding the impact of microgravity on the printing process.
ESA shipped a 3D printer to the ISS in January 2024, which was installed in the ISS by ESA astronaut Andreas Mogensen. It is a 3D printer developed by a team led by Airbus Defence and Space SAS. The printer weighs about 180 kg and is capable of printing objects in metal. In doing so, it uses a type of stainless steel that is widely used in medical implants and water treatment, among other things, due to its high resistance to corrosion.
Heated with a laser
For the printing process, ESA feeds a wire of stainless steel into the printer. The printer then heats the material using a powerful laser, which is about a million times more powerful than the average laser pointer. This laser melts the wire, after which the metal liquefies and is added to the print.
"The melt pool of the printing process is very small, on the order of a millimetre wide, so the surface tension of the liquid metal keeps it safely in place in weightlessness. Still, the melting point of stainless steel is about 1400 °C, so the printer operates inside a completely sealed box, preventing excess heat or fumes from reaching the Space Station crew. And before the printing process begins, the printer's internal oxygen atmosphere must be vented to space and replaced with nitrogen - the hot stainless steel would oxidise if exposed to oxygen," explains metals scientist Advenit Makaya from ESA's Directorate of Technology, Engineering and Quality.
Controlled from Earth
ESA will control and monitor the printer from Earth. "Metal 3D printing presents a greater technical challenge, with much higher temperatures and metal melted with a laser. This involves ensuring the safety of the crew and the Station itself - while maintenance options are also very limited. However, if successful, the strength, conductivity and stiffness of metal would take the potential of 3D printing in space to new heights," ESA technical officer Rob Postema explained at the launch of the 3D printer.
Four shapes were chosen to test the 3D printer. The four prints are all smaller than a soda can, weigh less than 250 grams per print and the printing will take about two to four weeks. The planned printing time is limited to four hours a day because of noise regulations on the Space Station - the printer's fans and motor are relatively noisy.
Shipped to Earth
So the first of these four prints has now been shipped to Earth. ESTEC will test the test object in its Materials and Electrical Components and compare it with objects printed on Earth. It thus aims to identify the impact of microgravity on the printing process. The test object has already been produced in the summer. A second test object will go to the Technical University of Denmark (DTU). This object was printed by ESA in December.
Eventually, ESA intends to use the knowledge gained during the project to create a circular space economy and recycle materials in space to make more efficient use of available resources. For example, by recycling parts of old satellites into new tools or structures. A 3D printer can play an important role here; it allows astronauts to print these tools and structures on location.
'Promising'
Tommaso Ghidini, Head of the Mechanical Department at ESA: "Metal 3D printing in space is a promising opportunity to support future exploration tasks, but also beyond, to contribute to more sustainable space operations through in-situ production, repair and perhaps even recycling of space structures, for a wide range of applications. This includes the production and assembly of large infrastructure in orbit, as well as long-term settlements on planets. These aspects are important focal points in ESA's upcoming technology cross-cutting initiatives."
Author: Wouter Hoeffnagel
Photo: LoganArt via Pixabay
