How Can Metallic Glass Get Us Into Space?
Imagine an alloy that can withstand the harshest environments of space without becoming brittle. Not only is this futuristic material made on Earth, but you may also own products made of this material, such as golf clubs or cellphones.
Researchers have discovered the benefits of bulk metallic glass (BMG)
when designed with injection molding technology. BMGs have been around since the 1960s and form from the extreme heating and quick cooling of metal to form an amorphous material.
NASA scientists are using this new material for gears in space robots and rovers, but the future of space exploration to extremely cold planets and moons may be possible with metallic glass incorporated onto NASA spacecraft.
How Bulk Metallic Glass Forms
To form bulk metallic glass, the atoms within the metal must lose their organized structure through a heating process that turns the metal into a liquid. If allowed to cool slowly, the liquid metal’s atoms will rearrange into the same organized pattern. To make the atoms stay in a randomized structure, the liquid metal cools automatically through a process at a temperature of 1,832 degrees Fahrenheit per second (1,000 degrees Celsius).
This randomized structure is metallic glass. Just like glass, this new material can flow easily when heated. The alloy becomes bulk metallic glass when it measures greater than 1 millimeter. BMG is pliable due to its low melting temperature, and this allows researchers to create gears using injection molding technology, similar to the process for plastics.
The Benefits of BMG
Although useful on Earth, steel and other materials in the harsh environments of space can lead to breakdowns of machines or an overuse of lubricant. Gears made of BMG can run without lubricant up to a temperature of minus 328 degrees Fahrenheit (minus 200 degrees Celsius). In order for rovers like the Curiosity Mars to work, the heating element for the lubricant receives its power from necessary devices on board. With BMG, this will no longer be necessary.
Using BMG in place of steel may prove to be cost-effective for future space exploration. For example, strain wave gears center around a flexible metal elliptical core that changes shape as it spins. It is costly to mass produce, but required to keep humanoid robotic arms from shaking, resulting in a smoother performance.
If scientists can use BMG instead of steel, it will increase the bottom line while also ensuring the strain-wave gears can operate in extremely cold temperatures without needing lubricant or becoming brittle.
What the Future Holds
NASA’s Jet Propulsion Laboratory (JPL), along with Caltech and UC San Diego, are conducting tests on BMG for use in not only high-precision robotics, but also in NASA spacecraft. Using the bulk metallic glass will allow space missions to harsh environments such as Jupiter’s icy moon, Europa. Although the scientists were using BMG for robotic gears, the alloy is in performance testing for planetary gearboxes, JPL spacecraft and rovers.
NASA is also investigating bulk metallic glass in the absence of gravity. By creating hardened foam from BMG, the new material has a higher strength-to-weight ratio and is lighter. Using lighter materials means less propellant burns during a space mission.
By taking the metallic glass foam and expanding it in microgravity and a vacuum, scientists learned that metallic glass can potentially shield spacecraft from micrometeorites and space debris. The space applications for this form of metallic glass include moon and Mars space structures and long-term space flights.
Researchers continue to test the potential benefits of metallic glass in different forms. This new material may be the solution to spacecraft challenges and could launch humans safely into space to finally explore the galaxy.
|Credit: Megan Ray Nichols – Science Writer|