NASA is Testing Shape Memory Alloy Wheels

Rovers on alien worlds need to be built of strong stuff. The dry rugged terrain can be punishing on the wheels as they explore the surface. In order to prevent the damage to the wheels, NASA is testing a shape memory alloy material that can return to its original shape after being bent, stretched, heated or cooled.  NASA has already used this material for years but never in tires, in what may be its perfect application.

Rovers are a common sight now as they explore the surface of other planets. Their versatility and ability to respond to the environment and commands from mission controllers make them a valuable exploration tool. Cameras, sensors, collection instruments and analysis tools are common onboard systems that provide information about the local environment. There have been a number of well known examples such as the Mars rovers; Spirit, Opportunity, Curiosity and Perseverance. They have helped us to learn about the geology, atmosphere, presence of water and habitability of the planet. Taken Mars as a case in point, we have only explored 1% so there is most certainly still a need for robotic rover exploration. 

Perhaps the most robust aspect of a rover is its wheels and tires. They must be capable of coping with rugged, uneven and rocky surfaces yet light enough not to cost a fortune to launch to the alien worlds. NASA has recently undertaken and completed a rigorous round of testing of a new tire using revolutionary shape memory alloys material. The tire technology was developed at the Glenn Research Center in partnership with Goodyear Tire and Rubber. 

The shape memory alloys have been used for numerous applications due to their unique feature of being able to return to their original shape after being deformed. They are typically made from combinations of metals like nickel and titanium which exhibit the property known as super-elasticity. The fascinating property allows the material to ‘remember’ its original shape and have been used in medical devices like stents, wires and various aerospace components. This is the first time NASA have explore their use in tyres. 

The idea about their use in rover wheels came about rather by chance. Dr. Santo Padula II, materials research engineer at NASA Glenn Research Center came across Colin Creager a NASA mechanical engineer while leaving a meeting. Creager explained about the work he was doing in the Glenn Simulated Lunar Operations Laboratory (a simulated lunar surface) to improve rover performance. Having enjoyed a tour of the facilities, Padula noticed the rover tyres were made of steel. Padula immediately realised that the steel wheels would get irreversibly damaged through use ultimately leading to their failure to provide traction. On discussing the matter, Creager explained it was the only problem they couldn’t solve. 

As a materials researcher Padula told him about his  work on a new alloy that would solve the problems with wheel irreversible deformations. The SMA tires concept was born. The two joined forces to develop the first nickel-titanium tires that would deform but return to their original shape and, after rigorous testing, the SMA tires became the solution to Creager’s problem. 

The team is now looking for other ways that SMAs can be used in other space exploration such as habitat protection. The extreme environment of space with meteoroid impacts being a regular occurrence make memory alloys the ideal solution. As robotic exploration continues apace and human exploration of our Solar System moves forward, SMAs look set to be a real game changer in ensuring safety and continued operation of a multitude of space hardware. 

Source : NASA Sets Sights on Mars Terrain with Revolutionary Tire Tech

Link : https://www.nasa.gov/technology/nasa-sets-sights-on-mars-terrain-with-revolutionary-tire-tech/