Today an article in Space.com appeared about tests a company Made In Space did with two 3D printers during a few zero-gravity flights. It is unclear from the article if the tests were successful or not. Regardless there are a couple of reasons why 3D printing makes so much sense.
The first requirement is for manned space flight into our solar system is that we can actual do manufacturing in space. At the moment all stuff is hauled from Earth and brought to space. Sometimes some assembly is required but we send mostly finished products in space. This limits us to wander very far from earth. The production, testing and shooting things into space is extremely costly and time-consuming.
The second requirement is that we need to be able to fix what is broken — even far from home. When we send people to Mars you cannot just order and replace a broken part. Because of this reason spaceships and space equipment are build according to the highest quality standards possible to avoid that they break. But of course things break nonetheless. Just imagine a design flaw which causes a part to break. If we would lower quality standards and can accept things will break in space the cost of design and manufacturing for space equipment can go down significantly.
The third requirement is when we venture further in space we cannot prepare 100% for what we will find or encounter. We need to be able to adapt existing equipment or make new ones.
The fourth requirement is that we simply cannot take everything with us.
Here comes 3D printing to the rescue. It offers a few solutions to these problems. 3D printers allow to manufacture on the spot using basic materials. On a space mission only these basic materials should be on board. I can imagine that we would mine local resources like moon dust to build parts.
When parts fail during a mission because of design flaws astronauts can modify the design — or even receive it from earth — and build an improved part on the spot. New parts can be created as well and produced for opportunities or problems we could not envision when the mission started.
The current state of 3D printing is still not up to the level it is good enough to actually solve the aforementioned problems but I am confident that we can get there. I can only imagine what will happen when NASA would put her weight behind this technology and actually starts to move this industry forward like she did in other industries as well.