Wed, 23 October, 2024
An electron beam welding gun designed and manufactured at TWI has created the first-ever autonomous weld in space.
The one-centimetre aluminium weld is now at the European Space Agency’s (ESA) Materials and Electrical Components Laboratory Centre in The Netherlands, where it is being compared against identical samples produced on Earth.
ESA engineers are testing the weld through focused microscope examinations, hardness testing and X-ray computed tomography.
ESA Materials Engineer, João Gandra noted, “If human space exploration is going to become truly sustainable and self-supporting, then in-space manufacturing will become commonplace, with the ability to weld being an important element of that vision. So we need to check how easy it is to weld in space.”
Although electron beam welding is highly controllable, penetrating deep into the metal to be welded, with no wasted energy, it requires a vacuum to prevent the beam from scattering in the presence of gas. While a challenge on Earth, this requirement not only makes the process a good fit for space operations, but also means it is already heavily automated and computer controlled.
Despite this automation and the lack of atmosphere in space making electron beam welding a good solution, there is a need to investigate how performing the join in orbit affects the weld.
The ESA’s João Gandra explained, “The weightlessness prevailing in space means we aren’t working with the same gravity-driven physics we normally take for granted. For instance while convection currents influence the way a molten metal ‘weld pool’ forms, cools and solidifies on Earth, in microgravity molten metals behave more like liquid blobs, shaped by surface tension instead. Then there are other complex variables such as space radiation and external vacuum to consider,” adding, “Right now we don’t really understand how these factors might interact, and the consequences they might have on the resulting material properties for any product. We can run computer simulations, but what we lack normally is any sort of empirical data to calibrate and improve our predictions. Which is why this spot weld is so valuable to us.”
The experiment, which was originally initiated by US start-up ThinkOrbital, took place inside a cylinder around the same size as an office water dispenser containing a carrousel of relevant aerospace aluminium alloys, with a second cylinder containing batteries to power the welding system plus avionics for remote operation and data transmission.
This is not the first time that welding has been attempted in space, with the first experiments taking place on the USSR’s Soyuz-6 spacecraft in October 1969, then aboard the US Skylab and Soviet Salyut-7 space stations in 1973 and 1984 respectively. There were also plans to develop a multi-purpose welding tool for maintenance on the International Space Station in the 1990s, but this collaborative US-Russian project was abandoned due to safety concerns and logistical difficulties.
As a result it has been 40 years since welds have been performed in orbit and never autonomously before now. The system was taken into orbit on a SpaceX Falcon 9 that was launched from Cape Canaveral on 6 May.
ThinkOrbital CEO and co-founder, Colonel Lee Rosen (USAF, retired) said, “This technology is critical to humanity’s future in space. Not only are we demonstrating ThinkOrbital's technology for in-space construction, we're also contributing to ESA's important scientific research and understanding of revolutionary technologies that will improve our collective ability to work and live in space.”
TWI has experience in creating bespoke electron beam solutions for a range of industries and this system may be capable of cutting and additive manufacturing in space as well as welding.
To find out more about TWI’s work with electron beam systems or our capacity as the ESA Technology Broker for the UK, please email contactus@twi.co.uk.