[galangalalgol]

I like the odea of reference frames. But it isn't just geographic. The unix clock on a starlink is doing double digit mach and goes horizon to horizon in minutes. GPS satellites have always had to account for relativity, so we could look to that system... Hmm, seems gps time doesn't add leap seconds, only using those already added when it started ;)

[SAI_Peregrinus]

Sure, you can define the reference frames to allow any orbit on any body. Mars landers & orbiters have slightly different time due to general & special relativity than Earth's surface, and also don't need Earth days/months/years, for example.