Date:18 November 2010
Nasa and The Goodyear Tyre & Rubber Company were honoured with the R&D 100 Award for an airless tyre capable of transporting large, long-range vehicles across the surface of celestial bodies, such as the Moon or Mars. The R&D 100 Awards ceremony, billed as the “Oscars of Innovation”, was held last week in Orlando, Florida.
The tyre, developed last year, is constructed out of 800 load bearing springs. It is designed to carry much heavier vehicles over much greater distances than the wire mesh tyre (which Goodyear also contributed to) that was previously used on the Apollo Lunar Roving Vehicle (LRV). The new tyre could allow for broader exploration and the eventual development and maintenance of planetary outposts. It might also have applications on Earth.
According to Vivake Asnani, principal investigator for the project at Nasa’s Glenn Research Centre, the tyre being recognised for an R&D 100 Award had to meet a significant change in requirements that required innovation. “With the combined requirements of increased load and life, we needed to make a fundamental change to the original moon tyre,” he said. “What the Goodyear-Nasa team developed is an innovative, yet simple network of interwoven springs that does the job. The tyre design seems almost obvious in retrospect, as most good inventions do.”
The Spring Tyre was installed last year on Nasa’s Lunar Electric Rover test vehicle and put through its paces at the “Rock Yard” at Nasa’s Johnson Space Centre where it performed successfully.
“This tyre is extremely durable and extremely energy efficient,” noted Jim Benzing, Goodyear’s lead innovator on the project. “The spring design contours to the surface on which it’s driven to provide traction. But all of the energy used to deform the tyre is returned when the springs rebound. It doesn’t generate heat like a normal tyre.”
According to Goodyear engineers, development of the original Apollo lunar mission tyres, and the new Spring Tyre were driven by the fact that traditional rubber, pneumatic (air-filled) tyres used on Earth have little utility on the Moon. This is because rubber properties vary significantly between the extreme cold and hot temperatures experienced in the shaded and directly sunlit areas of the Moon. Furthermore, unfiltered solar radiation degrades rubber, and pneumatic tyres pose an unacceptable risk of deflation.
According to Asnani, “The Spring Tyre does not have a single point failure mode. What that means is that a hard impact that might cause a pneumatic tyre to puncture and deflate would only damage one of the 800 load bearing springs. Along with having this ultra-redundant characteristic, the tyre has a combination of overall stiffness yet flexibility that allows off-road vehicles to travel fast over rough terrain with relatively little motion being transferred to the vehicle.”