NASA has actually thought through this problem and created SPICE, which lets you convert between different time systems, some relativistic and some not, as well as doing conversions between various reference frames: https://naif.jpl.nasa.gov/naif/index.html

Not sure if you are speaking from experience, but if that is the case, and this is true, then NASA as an organization seems to be a poor judge of what's important.

Even now with everything being virtual, I get invites to brown-bag type events probably 3-4 time per week. I can go to one or two, but there's no way I can fit every single one into my schedule.

The other question is why we have so many meetings per project. That one's tougher to tackle and I don't really have an answer. The one thing that I have identified is that we're very in to making sure that everyone has their say on things before taking action. That's a good thing overall, but it also leads to tremendous meeting bloat. A meeting that would only take 5 minutes if everyone restricted themselves to discussing critical issues before making a decision regularly takes a full hour in which we examine every pitfall, no matter how minor.

I wonder if there would be a benefit in your case if folks had to follow a similar process to the one Amazon requires for its meetings (this may be something NASA already does, but I will admit I'm projecting a bit here and am wishing my organization required some writing before calling for a meeting):

> We don’t do PowerPoint (or any other slide-oriented) presentations at Amazon. Instead, we write narratively structured six-page memos. We silently read one at the beginning of each meeting in a kind of “study hall.” Not surprisingly, the quality of these memos varies widely. Some have the clarity of angels singing. They are brilliant and thoughtful and set up the meeting for high-quality discussion. Sometimes they come in at the other end of the spectrum.

> ...

> Here’s what we’ve figured out. Often, when a memo isn’t great, it’s not the writer’s inability to recognize the high standard, but instead a wrong expectation on scope: they mistakenly believe a high-standards, six-page memo can be written in one or two days or even a few hours, when really it might take a week or more! They’re trying to perfect a handstand in just two weeks, and we’re not coaching them right. The great memos are written and re-written, shared with colleagues who are asked to improve the work, set aside for a couple of days, and then edited again with a fresh mind. They simply can’t be done in a day or two. The key point here is that you can improve results through the simple act of teaching scope – that a great memo probably should take a week or more.

https://www.sec.gov/Archives/edgar/data/1018724/000119312518...

I'm very thankful for the creators of https://www.worldtimebuddy.com/ handling time zone weirdness, etc, so that I can still get to Zoom calls on time (usually). I don't know how the Moment developers can ever think it's "done" - "We now generally consider Moment to be a legacy project in maintenance mode. It is not dead, but it is indeed done."

Solar system time: https://en.wikipedia.org/wiki/Barycentric_Coordinate_Time

* https://www.kimstanleyrobinson.info/content/martian-calendar

See also:

* https://en.wikipedia.org/wiki/Timekeeping_on_Mars

The big problems come from huge Earth assumptions about interval duration and interval sequencing being violated. A lunar day is 29.5 Earth days. Does the lunar calendar use solar days, and just have absurdly long weeks and years? Maybe the years are standard Earth length, they just don't use weeks or months. Does a lunar society have a shorter "not-day" that replaces the way Earth uses days, and now everything needs to handle this new unit of time? Do days still get measured as solar intervals, and we just decide it's okay for days to be longer than weeks on the moon, so it stays Tuesday for a month at a time?

There are no days, weeks, months, years. Just count the seconds and make sure everyone knows the epoch you started at.

Now, let's suppose you have a permanent settled outpost on Luna. You still use accumulated seconds as your time basis, but for casual conversation, you can talk about any Earth time marking that makes sense to you -- next Tuesday, or March 20th, or "in three months". You might occasionally care about whether it's bright or dark outside, but the tidal lock means that local weeks and months really aren't useful.

The hard thing is when you actually care about both the time on Earth and the local time/date/season of a planet you are interacting with naturally. Let's hypothesize a terraformed Venus, and while we're at it, let's change the axial tilt from 2.mumble degrees to 24 degrees. That gives us a 224ish terrestrial day V-year, a 1.92 V-day V-year, and approximately eight seasons per V-year, each being 56 days long.

On that planet, you get to go outside and enjoy the fresh air, but you want to know what season it is more than you want to know what month it is:

dark-winter, dark-fall, dark-summer, dark-spring

bright-winter, bright-fall, hell, bright-spring

(Venus rotates backwards, that's why the seasons are all funny.)

But when you want to know when the next shipment of Earth whisky is coming, you ask a computer.

UTC is better, because at least it is aware of leap seconds, but performing any calculation spanning a year's end involves consulting a database of leap seconds. Notably these aren't determined much in advance, so such calculations involving future dates will also involve leap-second errors.

TAI is best (for non-relativistic non-sidereal purposes), as it is not adjusted to account for leap seconds. You can calculate with it without trouble.

(All three of the above are based on the atomic SI second, so despite their differences, their seconds tick synchronously.)

UTC is not a great choice for a universal interplanetary time system, as it's designed to work on just one planet, for just one calendar system. It'll work fine while we're asking humans on Earth to oversee robots on the Mars, but will fall down pretty quickly once humans take permanent residence on celestial bodies that don't have Earth's rhythms.

Leap seconds are based on conditions here on Earth and wouldn't really be needed on Mars or Venus. They might have different peculiarities though, and they wouldn't be usable on Earth. In that situation, a single point of reference would be useful for conversions.

Maybe the "stardate" of the future will simply be Unix Time, but based on TAI.

Once you get into relativistic effects you need something better, but for practical purposes UTC and TAI are just fine for the foreseeable future. The days just become a meaningless abstract concept.

On the Moon and Earth you can just use UTC like ISS does.