What’s the most useful thing a 3D printer could print? Metal automobile or aerospace parts? A concrete building? Medical supplies? Even more useful would be something that would produce all of those things and more, on its own: a 3D printed 3D printer. Researchers in Canada have been looking into the possibility of making a 3D printer that could replicate itself in its entirety, which could potentially be used to build settlements in space ready for the arrival of humans (as well as other structures).
The research project is being carried out by the Department of Mechanical and Aerospace Engineering at Carleton University in Ottawa, led by associate professor Alex Ellery. "Our starting point is the RepRap 3D printer, which can print many of its own plastic parts," he says, the Rep Rap being an open-source 3D printer first developed at the University of Bath in the UK. The RepRap concept allows 3D printers to be made at a low cost by printing their own components.
A Reprap 3D printer
"I believe that self-replicating machines will be transformative for space exploration because it effectively bypasses launch costs," Ellery says, the idea being that a 3D printer could be sent to the moon, where it would start replicating itself. Eventually these 3D printers would set to work producing all the necessary equipment and infrastructure to establish a lunar base.
Obviously, these lunar 3D printers would be limited to using materials that are locally available, mostly extracted from the moon dust known as lunar regolith. The printer could be fitted with a robotic arm, which would scoop up the regolith, after which the printer would heat up the regolith to around 900 degrees using sunlight through a frensel lens. Any volatile gases stored in the lunar soil would be removed through this process, and the remaining material could be separated to obtain a mineral called ilmenite. Ellery says that iron could be extracted from this mineral, and silicone plastic could also be manufactured from resources on the moon.
Ellery’s team is currently using a mixture of polylactic plastic and iron to 3D print two parts of the motor, the stator and the rotor. But another important part that needs to be made are aluminium coils, which would replace the wire coils currently used by the motor. These aluminium coils could eventually be replaced on the moon by fernico, an alloy made from iron, nickel and cobalt.
Unfortunately, the team is currently having issues with the power that could be provided to the motor by the coils. According to Ellery, the magnetic field is "actually quite weak, so we are trying figure out ways to add more layers to increase the amount of current that goes through them. But eventually, what we will do is that we will integrate that into the motor so that will give us a complete core, which is 3D printed."
The 3D printed motor should be fully functional within two months, but the electronics part of the printer will take a lot longer to replicate. The lunar environment would pose problems for 3D printing electronics in the normal way.
"We have looked at vacuum tubes because trying to create solid-state electronics would be virtually impossible on the moon," Ellery said. "If you use vacuum tubes, the only materials you need are nickel, tungsten, glass, essentially, and Kovar, all of which you can make on the moon." Circuit boards for the self-replicating 3D printer would be modelled after the neural network of the human brain.
If the self-replicating 3D printer project is eventually successful, it could point the way forward for an exciting new era of space exploration and eventually settlement. However, even if lunar civilization remains an impossible dream, current space activities could also benefit greatly from self-replicating machines. 3D printers in satellites could produce solar panels to capture energy from the sun’s rays, as well as shields that would protect the increasingly fragile environment from the effects of solar radiation.


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