THE BOOSTER ROCKETS that lift the Space Shuttle off its launchpad – those twin bright red cylinders either side of the shuttle – are significantly taller than the shuttle itself. The reason why is surprising.
The rockets are built at a plant some distance from the launchpad, and as they’re much too big to go by road the only way of getting them there is by train. And trains are limited to the width of the track, which is four feet eight and a half inches.
The reason the tracks are that width is that when the first train carriages were made in England in the 19th century, they were regular road carriages fitted with different wheels. It was much easier to adapt existing carriages than to commission new ones.
Road carriages have wheels of a standard width because they fit the ruts in the road made by previous carriages. And the reason the ruts in the road are that width is because that was the width of the wheels on a Roman chariot, which made the ruts in the first place.
The chariots were set to that width so they could follow the ruts made by the hooves of the horses that were pulling them – two horses beside each other, making two sets of ruts.
So the design of the Space Shuttle is due directly to the width of a Roman horse’s bottom.
