[kej]

We already have separate planet times, for what it's worth [1].

I can't find it now, but I remember listening to an interview with a scientist involved with one of the Mars rovers who converted his whole family to Martian time for a few weeks or months after his rover landed, since those were the hours he was keeping for work.

[1] https://en.wikipedia.org/wiki/Timekeeping_on_Mars