Australia’s earliest tractor and deep space exploration
What does Australia’s earliest tractor have in common with Mars landing vehicles? The two surprising similarities are terrain and wheels.
NASA visits the outback
In 2019, NASA scientists together with members of the joint European–Russian ExoMars mission visited Australia’s outback to learn lessons about the oldest convincing evidence of life on Earth.
Did you know that the rocks in the Pilbara region are approximately the same age as those on Mars, ranging from 2.5 to 3.5 billion years old? This field trip provided essential knowledge that could be directly applied to the mission plan for landing a rover on the red planet.
Tractor wheels and steel lugs
Whether you are designing vehicles for exploration on Mars or for agriculture across our Great Southern Land, it is important to consider the terrain and design the wheels accordingly.
Australia’s earliest tractor, known as the EA, was made possible by the invention of the oil-driven internal combustion engine in the 1870s and was first released in 1908. In 1912, the engineers, Alfred and Ernest McDonald, improved the design and released the second generation, the EB.
The EB came 20 years before the invention and use of pneumatic rubber tractor tyres and so the wheels were made from steel. The rear wheels on the EB have steel lugs, in the form of low-level square section rods, welded to the surface to provide greater traction on softer ground.
During the early 1920s, Australia led the way in the development of steel lugs for agricultural purposes. For a while, Australian company Ronaldson Tippet was set to become the country’s largest tractor manufacturer with commissions to alter the wheels for several American tractor manufacturers. However, the invention of the rubber tractor tyre very soon surpassed the need for steel lugs.
Redesigning wheels for Mars
So why, with so many innovative improvements and advances in rubber technology, did NASA choose to develop metal tyres for a vehicle destined to explore the surface of Mars?
Perhaps the simplest answer is that the rover mission to Mars has cost well over $1 billion USD and tractor tyres, regardless of quality, are not puncture proof. A puncture on Mars could end the mission.
In the 1960s, NASA began to develop its own tyre technology for the first manned mission to the moon in 1972. The vehicle used large flexible wire mesh wheels with stiff inner frames to prevent over deflection and, just like the wheels on the EB tractor, thin tread strips were used to enhance traction in soft lunar soil.
This is where the similarities between early tractor wheels and Mars landing vehicles end.
The technology, type of metal and engineering principles adopted for the wheels on the EB are very different to those adopted by NASA for their rover vehicle.
Today, tyres designed for space exploration are made from nitinol, a nickel and titanium alloy with extraordinary ‘super elastic’ (which has the ability to deform) and ‘shape memory’ capabilities (that is, the ability to return to its resting state without being damaged).
These tyres are impervious to punctures, do not require maintenance, are lightweight and designed to perform in the most extreme environments.
Back to Earth
The SMART (Shape Memory Alloy Radial Technology) Tire Company was formed to commercialise this new category of airless tyre for use on Earth and for exploration on the moon and Mars.
The company has developed tyres for automotive, cycling, agriculture, trucking and aerospace applications while also creating the ultimate lunar tyre designed to carry multiple astronauts and heavy cargo across the south pole of the moon.
Perhaps one day, rubber tyres will be superseded by metal tyres. I wonder what Alfred and Ernest McDonald would make of that?