By Mark Norfolk on Friday, August 6th, 2021
and Sarah Jordan
Welding in space is a topic with a longer history than most people realize. The first documented welds in space can be traced back to the Soviet Soyuz 6 mission in 1969 over 50 years ago. Read more about the crew’s experiments and near disaster welding at Wikipedia. But why would anyone want to weld in space? Or with more recent technology developments, why would anyone want to 3D print in space?
The most obvious reason for welding or 3D printing in space is for repair. There are currently 27,000 pieces of space debris in orbit that are large enough to be tracked. Moving at 17,000+ miles per hour, any one of these can lance a hole in space structures. Even tiny flecks of paint are known to cause serious damage on impact. A small piece of debris can puncture a hole in a spacecraft. Immediate repair techniques are needed to stabilize the situation and hopefully allow for the mission to continue.
Long term though, the real focus for welding and 3D printing in space is construction. Currently we build spacecraft mainly to support the loads experienced in launch. Once in space, most space craft experience almost no real structural loading. If engineers can figure out ways to manufacture in space, then our material efficiency can shoot to the stars. An additional benefit is that we can build far larger structures than will fit in launch vehicles. By launching raw materials and then welding in space, we can create the exact structures we need without having compromise designs just for launch.
Being able to solve these problems is why Fabrisonic is so excited by a recent NASA small business innovation research (SBIR) project. We are partnering with TGV Rockets to turn our Ultrasonic Additive Manufacturing (UAM) process into equipment that can repair damage to spacecraft and eventually help manufacture in orbit. UAM is a 3D metal printing process which joins thin metal foils to produce a three-dimensional product.
There are many benefits for UAM in space, including:
On a prior NASA SBIR project, our 20 kHz sonotrode was reconfigured and miniaturized into our 30 kHz device (Fig. 1). The goal was to shrink UAM to further reduce system weight and power usage. Not only did we prove that our equipment could shrink to meet NASA requirements, the resulting designs have been commercialized into our popular SonicLayer® 1200 UAM machine.
The next step to UAM in space is freeing the print head from its current CNC platform. The goal of this SBIR project is to develop alternative motion systems for our welding tool (Fig. 2). Having a flexible motion system, like a robot arm, could allow UAM to access and repair damage on spacecraft (Fig 3). This can also free the process from the restrictions of a build envelope here on Earth. Although our SonicLayer® 7200 already has a very large footprint at 72 x72 x 63 inches, a robotic UAM device would dramatically increase the potential applications for this 3D printing technique.
A low temperature, low energy, welding process on the end of a large motion system enables the possibility of constructing large structures in orbit. For instance, we could launch a densely packed load of beams into orbit. An autonomous system could arrange the beams into structures using UAM to link together these elements with metal printed at each joint. Imagine how large of a radio-astronomy dish that could be assembled using this method!
One day we expect to look up in the sky and know that up above, a UAM robot is making repairs and even building new structures in space.
Figure 2. Concept robotic arm with sonotrode device.
Figure 3. Schematic of a micrometeorite hitting a space craft and being repaired by Fabrisonic’s UAM in space.