When traveling through space, there are certain items you know you're going to need. A spacesuit? Most likely. A towel? Some say it's the most massively useful item you can have.For all the rest, NASA has a new plan: 3-D printers. In space.The agency plans to send a 3-D printer to the International Space Station in June, when the fifth SpaceX supply mission is scheduled.In a video published Monday, the agency explains that a functional 3-D printer would help astronauts keep a steady supply of all the little parts needed to keep the 15-year-old station in working order without having to deliver or find storage space for replacements."3-D printing provides us the ability to do our own 'Star Trek' replication right there on the spot," NASA astronaut Timothy "T.J." Creamer says in the video. The printer would "help us replace things we've lost, replace things we've broken or maybe make things that we've thought of that would be useful."NASA will be able to load software for items it knows the astronauts will need onto the printer beforehand but also will be able to upload new ones from Earth if needed.A model of the proposed 3-D printer, from private company Made In Space, recently passed a battery of tests at NASA's Marshall Space Flight Center in Huntsville, Alabama.Chief among the questions addressed: whether the printer can withstand the pressure of a launch and how it would perform in "micro-gravity" aboard the space station."The 3D printing experiment with NASA is a step towards the future," Made In Space CEO Aaron Kemmer said in a news release when the partnership was announced. "The ability to 3D-print parts and tools on demand greatly increases the reliability and safety of space missions while also dropping the cost by orders of magnitude."Niki Werkheiser, NASA's point person on the project, said 3-D printing will significantly improve efficiency and convenience for astronauts."As you might imagine on Space Station, whatever you have available in orbit is what they have to use," she said. "Just like on the ground, you have parts that break or get lost. When that happens, you do have to wait for replacement parts, or we have to use multiple spares that have to be launched -- which does require extra mass."So what types of things could easily be lost and reproduced on the printer? In the video, Creamer mentions tools used on the space station and small pieces of storage racks used to anchor them down. But a 3-D printer could also be used to replicate more ambitious items in space -- someday, maybe even a pizza.