Uncle Bill's Helicopter

“On September 23rd, 1999, the Mars Climate Orbiter, after travelling from earth to mars, missed its re-entry to the atmosphere by 143 kilometers, and burned to a crisp. Why? One engineering group used english units, the other used metric. 3 years of labor. Toast. They’d made a big mistake. They’d screwed up. Email to engineering: Clearly communicate essential facts. Otherwise, spaceships turn to smoke and ash. If you can’t convert…