Units in Pounds or Newtons – Can Spacecraft Survive?
There are two main systems used in the world for measurement: English System and Metric System. Each system was devised independently. The English system is used in only a few countries. The rest of the world uses the Metric system.
The English system uses names such as inch, feet, yard, and mile. Pound is used for weight or pounds of force. The Metric system uses names such as meter, kilogram, second, newton, and mole (not the animal). Newtons is used for force.
One may wonder does it really matter which system to use? If you want to build a spacecraft that orbits the planet Mars, the answer is yes.
In 1998, NASA launched the Mars Climate Orbiter. When it got to Mars, it either crashed into the planet or escaped the planet and went into outer space. Nonetheless, the mission was a wash. Why did this happen?
Lockheed Martin and NASA used different measurement systems in some of the computer software the orbiter had. In one case, Lockeed Martin used the English system and NASA’s software expected metric system values. This disagreement cause the spacecraft to fail to orbit the planet Mars.
See Mars Climate Orbiter for all the juicy details.