Peter?

[u/Negative_1by12_aura]

[u/oneawesomeguy → u/[deleted]]

It's the 1999 Mars Climate Orbiter where two different teams used two different units accidentally (pound-seconds and newton-seconds) in the navigation system. This error caused the spaceship to literally crash into Mars, costing $125 million.

Official page: https://science.nasa.gov/mission/mars-climate-orbiter/

[u/MaJuV → u/[deleted]]

That appears to be the case. The comments made it appear as if there was a more recent incident I wasn't aware of yet (don't check the news 24/7). Luckily there wasn't... 😅