After reading on regarding in situ manufacturing in space, I've found out there is already a 3D printer for plastic on ISS, and the company behind it works on a space craft to manufacture larger (metal?) structures.

Now I've found also an initial design of a 3D metal /glass printer available as open hardware from the RepRap community, based on electron beam welding. I.e. they want this printer to be able to largely replicate itself, as well, beyond printing solar cells or metal parts.


My question is - would such a printer (or specifically electron beam welding) work in space? And produce solar cells good enough for space use?


It seems, like space environment would not only be possible, but actually beneficial - although not necessarily for this specific device.

Both due to gravity introducing undesirable stresses, which make the construction bulkier than necessary (any structural/moving parts in gravity need to support their own weight besides overcoming the necessary inertia) and with ubiquitous high-quality vacuum - the process is intended to work in high vacuum conditions.

Cooling will be harder, as is cooling in space - good active radiators would become a necessity. That's an added difficulty but not an insurmountable problem. Also, standard 'for space' preparation of all mechanics and electronics - radiation-hardening (or shielding), protection against cold welding, etc.

What won't work with this specific device is the gravity-fed powder deposition.

The one gun will be stationary situated 1.159m above the build platform. A sensor pick up ring will be attached to a 12Kg gravity fed powder hopper just above the build surface with 2 powder wiper blades attached, using sliding slotted plates to release the powder. A second powder hopper will gravity feed the 12 kg powder hopper.

This obviously won't work in microgravity; even if the hoppers are fed through different means, the powder deposition and leveling through the wipers won't work; it depends on the powder settling down due to gravity (and vacuum keeping it from flying with the air currents). Alternate means would need to be used. Possibilities include sputtering of already heated metal to sinter on contact/impact, holding it down electrostatically, introducing small centrifugal acceleration by spinning the device, combining deposition with welding by directing a narrow stream of powder to be heated right above the surface, or some other means yet to be designed.

Obviously, there will be the whole difficulty of logistics surrounding the process:

  • preparation of the raw materials for printing (there's a long way from meteoritic iron to a powder ready to deposit using a 3D printer),

  • material acquisition and transport,

  • assembly and delivery of completed products (or transport of the device and materials to where the production is needed),

  • other minor processes involving materials we take for granted (copious pressurized air to blow away the unsintered powder from a finished part?)

...And in the end, this, plus aforementioned "standard 'for space' preparation" are the greatest barriers - as of "soon", we can make a proof-of-concept device that will print a solar cell in space. To make something actually practically useful, say, providing a constant supply of cells for an expanding space colony, would require at least several decades. There's a myriad of these "minor details", all are all critical, all rather difficult, all quite costly, require moderate amounts of research and an enormous amount of smart engineering and effort, plus associated mountain of money, and are the ultimate answer to "why aren't we doing it yet."

  • $\begingroup$ thanks @SF. - still I wonder which type of device will Made in Space' Archinaut use. $\endgroup$ – J. Doe Aug 13 '18 at 9:18
  • $\begingroup$ would you say, several account with taking into account the pace of technological progress assumed no global catastrophe happens? $\endgroup$ – J. Doe Aug 15 '18 at 10:11
  • $\begingroup$ @J.Doe: We're nowhere close to utilizing space resources in any way. 3D printing is the easy part. But without proper ISRU it's quite useless in space; the area where you'd want something manufactured in space from raw materials, as opposed to assembled from modules, is a narrow fringe if we need to lift the materials from Earth. So, yes, possibly a big several decades, until ISRU becomes more than a pipe dream. $\endgroup$ – SF. Aug 15 '18 at 12:21
  • $\begingroup$ sure you're right! would be great so see something like this for ISRU en.wikipedia.org/wiki/Lists_of_unsolved_problems. Actually I have been thinking what could be major breakthroughs to support further ISRU developments, so if 3D printing is the easy part what are currently researched "hard" parts? $\endgroup$ – J. Doe Aug 15 '18 at 12:27
  • $\begingroup$ ^^ ok possibly this ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050204002.pdf $\endgroup$ – J. Doe Aug 15 '18 at 12:34

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