Here's How NASA's Wild Airless Tires Work

[Buster's Uncle]

Here's How NASA's Wild Airless Tires Work
Popular Mechanics
Tony Markovich •February 5, 2018



Photo credit: NASA



NASA is constantly trying to reinvent the wheel, both literally and figuratively. While satellites and probes are exploring undiscovered reaches of space, engineers and scientists are attempting to create the perfect wheel and tire combination down here on Earth. NASA’s latest innovation is based on an idea that has been around for years, the airless tire, but uses shape-memory alloys as radial stiffening elements to maximize the advantages and capabilities. It goes by the uninspired name of Superelastic Tire.

Like many breakthroughs, NASA’s newest development was born from an issue with its previous tire. In the late 2000s, NASA was doing testing for motorhome-size lunar rovers. Back then, the airless spring tires utilized spring steel, and although they worked well, they were vulnerable to plastic deformation or dents when put under heavy loads. A chance visit from materials scientist Santo Padula to the Simulated Lunar Operations (SLOPE) lab at NASA’s Glenn Research Center resulted in a potentially revolutionary merging of technology. Padula suggested using shape-memory alloys in the form of radial stiffeners on the tire instead of spring steel.



Photo credit: NASA


The material used for this technology on this tire is an alloy based on stoichiometric nickel titanium. To get technical about it, other material atoms stretch to the point of breaking when taking on the duress of heavy loads. This nickel titanium alloy rearranges at an atomic level and regains its shape once the load is taken off. Hence, memory. According to Padula, this allows for 30 percent more deformation without permanent changes or damage. The memory alloys can take up to 10 percent “reversible strain,” as opposed to 0.3 to 0.5 percent the spring steels or composites are capable of. In prototype form, the tire looks like pliable chain mail.

The advantages of this type of tire are obvious. Not only does it eliminate potential issues with temperature or pressure affecting a gas-filled tire, it also eliminates the possibility of deflation. This newest prototype also removes the need for an inner frame, which saves weight. NASA says the alloys allow control of tire stiffness, too, which means the rovers could be adjusted for various loads on different types of terrains and the differing gravity of other planets.

Although these prototypes were created for rovers to be used on missions to Mars, NASA says the technology could trickle into real-world applications here on our own planet. Of course, traction, speed capability, and cost would be major issues, but commercial vehicles that only travel at low speeds and operate off-pavement could benefit. And just imagine how great these would be driving over potholes.


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