The infamous NASA tool bag lost in space during a November 2008 International Space Station (ISS) maintenance mission left the crew with one less grease gun and no way to replace the missing tool. In a few years astronauts may be able to restock lost or damaged instruments by simply 3-D printing new ones.
NASA will test the feasibility of 3-D printing in a confined microgravity environment early next June when it sends a microwave-size printer to the ISS for a series of experiments producing plastic and composite parts and tools. If all goes well, the space agency plans to install a permanent ISS printer in 2015.
In the near term such a machine would let the ISS crew replicate odds and ends—plastic clips to anchor cargo, for example—without having to wait for the next resupply mission. Further in the future the space agency imagines a day when raw materials mined from asteroids could be delivered to a spacecraft or orbital lab and used as 3-D printing fodder. The ability to resupply far from Earth would give such a vessel the ability to carry out longer, deep-space missions, assuming myriad other sticking points are worked out—fuel, food and radiation exposure among them.Test run
First things first: Astronauts will install the test 3-D printer—built by a company called Made in Space—in the ISS’s Microgravity Science Glovebox, an enclosed 255-liter work space located in the European Space Agency’s Columbus laboratory module. ESA developed the work space to allow terrestrial scientists from different disciplines carry out experiments in space, aided by ISS crew members via real-time data links and video. The work space is sealed and held at a negative pressure to enable the crew to manipulate experimental hardware and samples without the danger of small parts, particulates, fluids or gases escaping into the open laboratory module.
Made in Space’s printer builds objects by first heating a thermoplastic filament and then using an extrusion head to deposit the softened material according to a blueprint dictated by a computer-aided design (CAD) file. This printing technique—commonly used by inventors for quickly prototyping their designs—creates items from the bottom up, depositing materials in layers as thin as 0.04 millimeter.
3-D printers are generally designed to take advantage of gravity and surface tension to help form layers without air bubbles or other imperfections that weaken the finished product. “In the presence of microgravity all the components of a 3-D printer begin to float around, and even fractions of a millimeter of float can be detrimental to a print,” says Made in Space chief technology officer Jason Dunn. Without going into specifics—for competitive reasons—Dunn says that his company has developed “the first 3-D printer that is essentially gravity independent.”
Lack of gravity also means the ISS atmosphere offers no natural convection. This poses problems for managing heat, which is central to the 3-D printing process. “Keeping hot things hot and cold things cold requires new thermal-management methods compared to those found in terrestrial 3-D printers,” Dunn adds.
The prototype printer has passed a number of vibration and stress tests to determine whether it could survive a launch and function in microgravity. Parabolic test flights provided 20- to 30-second intervals of weightlessness in which to test the printer and yielded a limited set of performance data that NASA hopes to round out during next year’s ISS installation. Made in Space will present research from its early test flights at the American Institute of Aeronautics and Astronautics Space 2013 conference next month.
During the ISS test, the Made in Space printer will build a variety of objects, including mock-ups of tools and parts used on the space station. “The main goal of this project is to identify not only how the printer reacts when exposed to long-duration microgravity but also to determine if the materials change when being built in that environment,” says Mike Snyder, a founding partner of Made in Space as well as the company’s lead engineer and director of research and development.Station power limits