Rockets are expensive. Really expensive. A single Delta IV rocket, for instance, can cost more than $150 million. There are a lot of reasons for this: design, construction, and fuel costs are just a few. As we push towards more frequent access to space, various organizations are looking for ways to trim this. The SpaceX Grasshopper, for example, will hopefully be able to make some rockets partially reusable. NASA is exploring a different path - 3D printing. Why 3D printing? Many mechanical parts are milled from solid blocks of metal, which is a very wasteful process. If you could instead print the exact part needed, there would be almost no waste. This could reduce construction costs and lower a rocket's final price.
Before you try and print a rocket at home, these probably aren't the sort of 3D printers you're familiar with. Instead of laying down layers of brightly-colored plastic, these heavy-duty machines build objects out of metal. The basic process, though, is more or less the same. A machine lays down tiny layers of nickel-chromium metal, which are then melted with a laser to the layer below. Working from a computer design, the machine slowly creates the desired part.
NASA's latest effort comes in the form of a fuel injector. Like the fuel injectors in your car engine, this part delivers propellant to the engine chamber for burning. Sets of injectors deliver liquid oxygen and gaseous hydrogen to the fuel chamber. When combined, these elements produce an explosion of energy, which is directed out the back of the rocket as thrust. In this latest test, the system was able to provide ten times more thrust than any previous 3D-printed system.
But 3D printing has the potential to make a far bigger impact on space travel than simply lowering its cost. Imagine that a rocket delivers NASA's Orion capsule to the International Space Station (ISS). En route, a problem is detected with the capsule. Normally, mission controllers would have to decide whether the issue was serious enough to keep the crew from returning to Earth. They'd be stuck on the ISS until another capsule could be sent. If a 3D printer were on board, however, a replacement part could be fabricated and the mission could continue normally. It would be far too expensive and heavy to store one of each potential part on the station, but a 3D printer with only a small amount of powdered metal could accommodate them all.
If that doesn't seem worth it, potential astronauts might want to take note of this: NASA is also considering turning its 3D printers into short-order cooks. Instead of being stuck with the same few meals for an entire mission, 3D-printed food could accommodate everyone's tastes. Now, that seems like a machine worth having!