I heard this story by watching a recent lecture given by MIT’s Open Coursware initiative. It traces the history of how the rocket booster design of the Space Shuttle was influenced by Roman Empire horses. t goes a little like this.

  1. Thoikol is a Utah-based company that builds the rocket boosters. The boosters are transported to Florida via the railroad. NASA engineers wanted large boosters but were constrained by a tunnel along the railroad path that the boosters would take on their trip. The tunnel was just slightly larger than the railroad tracks which measure 4 feet, 8.5 inches wide. So why the weird dimension.?
  2. 4 feet, 8.5 inches is the width of the British railroads, and it was British engineers who built American railroads.
  3. The people who built the British railroads had initially built the British streetcar lines
  4. The people who built the streetcar lines used tools made for building coaches and those coaches had a track gauge. The coaches had the 4 feet, 8.5 inches track gauge because of the width of the British roads.
  5. It was the Romans who built the first British roads so they kept the width in building future roads.
  6. The Romans built their roads to move the Army and thus fit their war chariots.
  7. The Roman war chariot was built to accommodate the width of two horses!

So there you go, the reason the Space Shuttle booster rockets were designed and built as they are can trace their requirements back to butt of a Roman horse.