In the vacuum of outer space, cold welding can occur between pieces of metal of the same type, which can cause significant trouble. Humans have been mining and using metals for thousands of years, and in modern times, methods have been developed to make metals more resistant to environmental impacts. While some may believe that metal performs better in the vacuum of outer space without rusting or degrading, the vacuum environment actually presents many problems that can lead to serious consequences for space missions.
Joining metal pieces together has been a useful practice for a long time, traditionally done through welding which involves melting one or both pieces of metal, joining them together, and letting them cool. Nowadays, there are various methods available to weld metals, such as chemical, pressure, and molecular methods. A method that can take place in the vacuum of outer space is cold welding, where metals are joined without the need to melt them. However, there are specific requirements for cold welding to occur, including the metals being of the same type, clean, flat, and in a vacuum.
In cold welding, the Van der Waals forces between atoms become stronger when metal surfaces come close to each other, allowing them to weld together. For example, when two pieces of gold are placed together in a vacuum, the atoms on the surface of one piece will interact with the atoms on the surface of the other piece, creating metallic bonds that link them together. While cold welding can be difficult on a large scale, it is possible with the right conditions and pressure. On a nano-level, workers can create strong gold nanofiber welds.
Cold welding can pose significant challenges for space missions, with unexpected instances causing malfunctions. For example, the Galileo spacecraft flying to Jupiter in the 1990s experienced a failure to open its directional antenna due to cold welding between the arms. This incident resulted in the antenna being stuck, limiting the amount of data the spacecraft could collect. Understanding cold welding is crucial for ensuring the safety of space missions, especially those involving crew, as it can lead to serious consequences if not properly considered.