Agnirva Space Premier League - Expedition #32219: Melting Metal in Microgravity: The Art of Soldering on the ISS

Soldering—a process that joins metal parts together using a filler metal—is a basic but essential skill in electronics, construction, and space systems. But how does soldering work in space, where there’s no up or down, and where heat behaves in strange ways? That’s the question NASA aimed to answer with the Soldering in Reduced Gravity Experiment (SDTO 17003-U) aboard the International Space Station (ISS).

Led by Dr. Peter Struk at NASA’s Glenn Research Center and supported by the National Center for Space Exploration Research and ZIN Technologies, this experiment focused on understanding how molten metals behave in microgravity. In zero gravity, convection—the natural flow of hot materials rising and cooler ones sinking—doesn’t happen. This can dramatically change how heat spreads and how metals fuse.

The experiment aimed to evaluate different soldering techniques and materials in this unique environment. Astronauts performed controlled soldering tasks and observed the results in real-time using video capture and sensors. These tasks were designed to simulate real-world repairs that might be needed on spacecraft or satellites, where reliable joining of electrical components is mission-critical.

Soldering in space isn’t just about repairs. It’s also about future construction. As humanity moves toward building habitats on the Moon, Mars, and beyond, in-space manufacturing and assembly will become increasingly important. This research provides the groundwork for developing robotic or crew-performed soldering tasks during long-duration missions.

The experiment also revealed valuable insights into how flux behaves in space, how surface tension changes the shape of solder beads, and what methods result in the strongest joints. This data is useful not only for space missions but also for improving soldering quality and automation on Earth.

The results of Expedition 14’s soldering study have helped NASA refine tools, techniques, and training programs for astronauts and engineers alike.

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