TIL that NASA lost a $330m Mars Orbiter in 1999, immediately before mars orbit was achieved, because one of the contracted US companies used imperial units instead of metric.
Metric vs Imperial Units: How NASA lost a 327 Million Dollar Mission to Mars
https://everydayastronaut.com/mars-climate-orbiter/
Imagine a simple conversion error caused a multi-million dollar mission to go puff! We explore how the Mars Climate Orbiter was lost in 1999.