A "new" Martian calendar? Frankly this is a bit of technical "fluff" for a SF novel where a good deal of the story takes place on well established colonies on Mars, but it's still an interesting technical question to think about. If there were substantial, well established colonies on Mars, what would they use for a calendar and time standard? The obvious choice would be a calendar and time standard based on the motion and seasons of Mars, but that approach ignores some rather prickly conversion problems between Martian dates and times, and those used on Earth. When you consider how important dates and times are, just in areas like commerce trade and the law, and then also consider how resistant lawyers and businessmen are when it comes to changing systems like this that impact their day to day lives, my own view is, that any kind of independent "Martian calendar", however efficient and or elegant it may be in terms of the realities of celestial mechanics, is very unlikely to ever come into widespread use by a predominately lay population. Scientists would use it, but everyone else's eyes would glaze over, and they'd groan and complain about it being "too complicated" and "a pain in the neck". As a result there'd never be the political will for any governing body to arrive at some sane standard (even assuming there IS the political will to come up with a standard, the chances of a "sane" standard being the result of months to years of political wrangling strikes me as unlikely as all hell). So how will a "standard" develop? Frankly I don't think any independent Martian calendar ever will develop. Instead, I suspect a bastardized version of Earth's time and date standards will emerge, that works something like this... A MARTIAN "DAY" - consists of 24 hours with time and time zones *directly* matched to those of Earth were "midnight GMT" = say, "midnight OMT" (aka midnight Olympus Mons Time), and the extra 37+ minutes in a day takes on the name "drop time", traditionally a break period of 37+ minutes a day where at "noon" all Martian clocks essentially freeze for those 37+ minutes (Martian clocks have a small "subface" that counts down "drop time" until the clocks restart). THE MARTIAN "YEAR" - doesn't exist. It's ignored in favor of staying in synch with dates on Earth. The Martian seasons come and go with no relationship at all to the date or months of the year. Thoughts?