Space is, in some ways, a fairly forgiving place to work. Sure, there are sudden and unpredictable blasts of radiation, belts of high-energy particles, and the ever-present danger of meteorites, but the advantages are just as strong. There is (functionally) no gravity in orbit, so you can make odd or flimsy designs, no air or weather to batter and corrode materials, no insects or birds to muck up the machinery. In some ways, working in space is a designer’s dream, allowing virtually any shape to be practical.However, we don’t live in space, and anything we want to put up there has to first exist in space. That poses a number of problems, foremost of which involves the sheer size of many of our would-be space inventions. The space shuttle has (had) a big enough cargo area for some fairly large pieces of equipment, but the truly revolutionary stuff had to fold up, or be shipped in pieces and assembled in space. This introduces confounding challenges for designers and engineers who maddeningly have to accommodate an environment in which their creations will never actually operate. But what if we could build those things in space to begin with?That’s what SpiderFab from Tethers Unlimited aims to do. For more than a year, NASA has been collaborating with Tethers to create the space-fabrication system, and has just extended the contract by a further $500,000. The multi-armed space robot would 3D print the scaffolds and walls of large structures, so only the complex functional units need to be sent up after fabrication on Earth. The prime example is a the huge backbone of a major solar array — SpiderFab is projected to be able to make structures more than a half a mile wide.There are currently few details on exactly how SpiderFab will work. Specifically, how the basic idea of 3D printing will have to change to accommodate both the vacuum of space and NASA’s rigorous equipment requirements. Finding a printable material that will fuse quickly and with high strength without an atmosphere to act as a heat sink will be difficult — there are currently no projections for just how long it might take SpiderFab to complete a large-scale project.Still, these sorts of cost-cutting measures are absolutely essential. Perhaps the most famous is the space elevator, which would negate the need for expensive rocket fuel when putting things into orbit. Until such time as we can just build a dedicated power plant or two for slow ascents into space, though, SpiderFab might be the best option available.