1.5 - Why Measuring is Important!
The Mars Climate Orbiter
Designed to orbit Mars as the first interplanetary weather satellite, the Mars Orbiter was lost in 1999 because the NASA team used metric units while a contractor used imperial. The $125m probe came too close to Mars as it tried to manuever into orbit, and is thought to have been destroyed by the planet's atmosphere. An investigation said the "root cause" of the loss was the "failed translation of English units into metric units" in a piece of ground software.
The Vasa warship
In 1628, crowds in Sweden watched in horror as a new warship, Vasa, sank less than a mile into her maiden voyage, with the death of 30 people on board. Armed with 64 bronze cannons, it was considered by some to be the most powerful warship in the world. Experts who have studied it since it was raised in 1961 say it is asymmetrical, being thicker on the port side than the starboard side. One reason for this could be that the workmen were using different systems of measurement. Archaeologists have found four rulers used by the workmen who built the ship. Two were calibrated in Swedish feet, which had 12 inches, while the other two measured Amsterdam feet, which had 11 inches.
The Laufenburg bridge
What is sea level? It varies from one place to another, and different countries use different benchmarks. "For example, Britain has measured height in relation to mean sea levels in Cornwall, while France measures height in relation to sea levels in Marseille," says Dr Philip Woodworth, of the National Oceanography Centre Liverpool. Germany, for its part, measures height in relation to the North Sea, while Switzerland, like France, opts for the Mediterranean Sea. This caused a problem in Laufenburg, a town that straddles Germany and Switzerland. As two halves of a new bridge grew closer to one another in 2003, it became clear that, instead of being at the same height "above sea level", one side was 54cm higher than the other. Builders knew that there was a 27cm difference between the two versions of sea level - but somehow it was doubled, rather than cancelled out. The German side reportedly had to be lowered before the bridge could be completed.