But I could have sworn my teacher my freshmen year of highschool told me that some smart guy at Nasa was off by a number, and some launch made to mars, it missed it and nearly WASTED millions of dollars for no good reason... But I am not sure if it was announced to the public, but pretty much it would be the same thing as of now.... Just off by ONE number, and there goes the entire project....
I didn't happen once, it's happened on several occasions!
metric-imperial conversions (or lack thereof) have caused a few failures.
A minus sign once took out a rocket!
...and it doesn't just happen to NASA:
http://www.around.com/ariane.html