Recently, NASA's been toying with the idea of 3D-printed spacecrafts, and the prospect alone has fans of the medium positively giddy. But in our 3D-printing-for-space frenzy, we've overlooked the simplest problem of all: Imperfect surfaces and outer space don't mix.

The potential of 3D printing in space is phenomenal. Not only does the process itself cut down on waste, but the lighter, 3D-printed parts would also mean less fuel consumption. Unfortunately, as you can see in the below electron microscope close-up, 3D printing also leaves you with slightly imperfect (read: rough) surfaces.

And while this is ok for Earthly matters, outer space demands precision. Any extra space between particles means a far greater risk of developing cracks. What's more, that space makes it easier for loose particles floating around to get caught in the bumpy, 3D-printed surface. Which is a big no-no for space-suitable materials, which are held up to a surgical standards of sterilization. According to the the European Space Agency (ESA), "Delicate satellite electronics or optics have in the past been fatally damaged by particle contamination or outgassing."


Now, in an effort to figure out how to make 3D printing a viable option for space travel, the ESA is launching an investigation in various surface treatments such as aluminum, titanium, and stainless steel, among others. The ESA explains:

Different manufacturing techniques, including laser and electron beam melting, will be assessed, along with surface treatments such as sandblasting, etching, nickel coating and painting.

The mechanical properties of the processed parts will be assessed for resistance to stress corrosion and the tendency to fracture.

Of course, this doesn't mean that our dreams of a fully 3D-printed rocket need to be dashed—at least not yet. There's still plenty of potential to be had, and a long, long way to go before we'll know if that potential could ever become a reality. [ESA]