Hacker News Reader

...well NASA (or its supplier) did try - the infamous Mars Orbiter crash[0]:

The primary cause of this discrepancy was that one piece of ground software supplied by Lockheed Martin produced results in a United States customary unit, contrary to its Software Interface Specification (SIS), while a second system, supplied by NASA, expected those results to be in SI units, in accordance with the SIS.

[0]: https://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_...

> According to NASA, the cost of the mission was $327.6 million

It probably makes the top 10 most expensive software defects of all time.

Microsoft Windows was likely #1.

Maybe not NASA, but what about its contractors? https://www.simscale.com/blog/nasa-mars-climate-orbiter-metr...

The gauges in the Apollo modules were all in US customary for the benefit of the pilots. AFAIK the underlying systems used metric internally, though.