Guys and gals, Europe lost a Mars mission due to a lack of corresponding units. It happens.

Personally, I spend some years in a metric country and learned in short order how to shift my thought process, as well as to read (modern) Arabic numbers. And, "thinking about it", should it avoid a Mars-type screw-up is, perhaps, not a bad thing. Any unit may be sufficiently divided to achieve necessary precision. I also spent a number of years working as a machinist for a company that made the liquid sodium pump seals for French breeder reactors. And the same machinist would make SAE parts on the same machine as he would make Metric parts - using the same measuring sticks, keeping all the while in his head how they divided and compared. That is what those guys did, and did it exceedingly well. Me, I was mostly QC - and signing off (literally acid-etching my name on a part or assembly) on their work.

Yes, we did think of dimensions and measurements. Every day. And we lost no sleep whatsoever on which was 'better'. As long as the parts fit.

Peter Wieck
Melrose Park, PA