Author Topic: Mars Timekeeping System  (Read 19921 times)

Offline Tony Whitehead

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Mars Timekeeping System
« on: 11/03/2016 02:53 AM »
I was thinking back to the Andy Weir novel, The Martian, and about how the time was based on elapsed mission time.  If things fall into place as Mr. Musk is planning, that method will have to necessarily change.  A quick Internet search later and I found this link:  http://ops-alaska.com/time/krutein/Marstime2.html

Comments?  Suggestions?

Offline RonM

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Re: Mars Timekeeping System
« Reply #1 on: 11/03/2016 03:29 AM »
It might be useful for colonists to have a Mars calendar based on the martian year.

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

http://www.giss.nasa.gov/tools/mars24/help/notes.html

A mars solar day (Sol) is 24 hours 39 minutes 35.244 seconds. I guess one second before midnight on Mars would occur at 24:39:34.244 instead of 23:59:59.  ???

Subdividing by more than a Sol will be confusing when communication with Earth. Of course, if the colonists want to use the SI metric system, then the second has to remain the same.

Offline biosehnsucht

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Re: Mars Timekeeping System
« Reply #2 on: 11/03/2016 04:42 AM »
I imagine you'd use both Earth days and Martian Sols (mostly unless corresponding with Earth or tracking Earthly holidays) to track local time (and use some variation of julian style calendar or something that at least has entirely newly defined months rather than trying to stretch out our regular 12 months to cover 668 days, or add ones to the existing names, since that would cause no end of confusion... ). You'd normally use Martian Sols locally, but generally any time keeping device (we live in the future now, there's not going to be many grandfather clocks operating on Sols) will be able to display the current date/time on Earth as well. There wouldn't be much attempt generally to try and force things to happen on Earth schedules, though I'm sure there's some people who would be celebrating Earth traditional holidays on the days corresponding on Earth just because they want to (so xmas twice a year, for example).

I think as for hours/minutes/seconds, keep the existing units and definitions, and just allow that every day has a weird fractional hour/minute/second. Again, we live in the future, our technology will save us from doing the math, we just know that there's ~24:39:30 in a day (ignoring the extra 5 seconds and change in common conversation, unless there's some kind of science/engineering reason it matters - you won't meat someone at the bar at 24:39:35.244, you'll say "I'll see you there around 24:30!").

As necessary the underlying time system may have various leap years/days/seconds/whatever to maintain sanity, since there's also not a perfectly divisible number of Sols in a Martian Year.

But generally, the h/m/s are the same, just more in a Sol, and different calenders with different names for months, and "new" (actually apparently already existing) words like yestersol and solmorrow, for conversational use. Technology handles all our timekeeping / conversion needs, just as it has been for some time (cell phones, etc).

I tried to find a reasonable division of sols into months that didn't involve silly 30/31/28 day nonsense but 668 sols, ignoring the partial sol, can only be broken down as far as 167 x 4 ... So I'm not sure if we use 4 day weeks and weird alternating month lengths (as we do on Earth), or 8 day weeks (and again weird month lengths, plus a half week somewhere), or stick to 7 days (of which they will rarely coincide with those of Earth, but might be important to some for religious reasons) and still, weird month lengths - and also a partial week again (this time of 3 days rather than 4). The easy option is just to forego weeks and months entirely and use just a straight up Julian system, but psychologically people may still want to have the idea of "weekends", etc. I just can't come up with a non-wonky system of weeks/months (just weeks is easier though).

Either way, it seems the most reasonable plan would be for those who wish to track Earthly traditions to do so separately in addition to local dates using the local Martian calendar, following the actual dates on Earth for their celebrations (xmas two times a year! yay! except not really). There might be new Martian traditions following the new Martian calendar, but probably best to make a clean break and just tear the bandaid off.

Offline MickQ

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Re: Mars Timekeeping System
« Reply #3 on: 11/03/2016 08:08 AM »
20 months of 33 sols leaves an 8 sol surplus that could be a designated festival/ carnival/settlement celebration period.  Martian clocks could run a little fast so that midnight on Earth and on Mars occur at the same instant or use the Martian Timeslip invented by Kim Stanlefy Robinson..  As far as I can see there is no easy way to sync the two planets together.

Offline Beittil

Re: Mars Timekeeping System
« Reply #4 on: 11/03/2016 08:32 AM »
I suppose in relation to Earth they could keep a schedule where they make contact based on UTC time, much like the ISS does.

Offline high road

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Re: Mars Timekeeping System
« Reply #5 on: 11/03/2016 09:24 AM »
Don't forget that people have prefered in the past to divide the year into 'useful' periods, where cycling events in the environment impacts daily activities in some way. So things like 'dust storm season', spare-solar-power season', 'annual meteor shower', 'holliday season' might make it onto the calendar eventually. That's how we ended up with our alternating month lenghts that we've been trying to standardize for milennia.

Religious feasts will continue to be held in reference to Earth time, like Islamic events use the Islamic calendar. But new religions might spring up.

Considering that the greatest impact on activity on Mars for a long time to come will be the arrival and departure of supply missions, maybe it'll be more effective to express time relative to the nearest launch windows, even if it's not fixed. By the time supply missions stop determining the activity in the colony, people might have gotten used to this system, so they no longer wish to change.

Offline Phil Stooke

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Re: Mars Timekeeping System
« Reply #6 on: 11/03/2016 09:50 AM »
We have been using Martian sols for landed missions since 1976 without any difficulty relating Mars time to Earth time.  So for time we need only look at how our Mars rover folk manage.  Dates are another issue, of course, but there is a perfectly good calendar of Mars dates in use now, just using Mars years and sols, used since 2000 on all Mars missions, orbital and surface.  People don't seem to need a week or month in the system.  I just want to emphasize that this subject has not just arisen in a vacuum, there is a longish history of this and a well-established literature, so changes are not very likely.

Online guckyfan

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Re: Mars Timekeeping System
« Reply #7 on: 11/03/2016 10:41 AM »
We have been using Martian sols for landed missions since 1976 without any difficulty relating Mars time to Earth time.

That's a group of scientists and specialists handle their job. I am quite sure settlers will use something else. They want a structue in their timekeeping they can relate to.

As they would not be very much exposed to the conditions outside they could even use the earth calender in sync with earth. Only the days adapted to the slightly different length of day. After all the Australians celebrate Christmas in summer, too.

Offline JamesH65

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Re: Mars Timekeeping System
« Reply #8 on: 11/03/2016 11:22 AM »
We have been using Martian sols for landed missions since 1976 without any difficulty relating Mars time to Earth time.

That's a group of scientists and specialists handle their job. I am quite sure settlers will use something else. They want a structue in their timekeeping they can relate to.

As they would not be very much exposed to the conditions outside they could even use the earth calender in sync with earth. Only the days adapted to the slightly different length of day. After all the Australians celebrate Christmas in summer, too.

???? Just use Martian days/years. Makes outside jaunts much easier - daylight matches the clock. It's the people on Earth who would need to sync with Mars, not vica versa. The guys on Mars are going to have it difficult enough without having to worry about what time they phone home.

Offline philw1776

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Re: Mars Timekeeping System
« Reply #9 on: 11/03/2016 04:04 PM »
Those living on Mars would want a sunlight oriented system for sols like we have on Earth.  I think it's a bad idea to alter the second proportionately as some elsewhere have suggested.  Although not noticed by Mars residents it could complicate engineering calculations and be a source of error.

My radical Mars quirky solution is to use normal Earth hours minutes and seconds but at midnight when all but the night shift and those wild & crazy late night Mars party animals are asleep, have the clocks go to Red Time where the extra 39 minutes 35.244 seconds are added and counted down before resuming at say 12:01.  Mars sols are preserved.  Everyone in the inner solar system is using standard seconds, etc.  And a party time is enshrined in unique Mars culture.
« Last Edit: 11/03/2016 04:05 PM by philw1776 »
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Offline JasonAW3

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Re: Mars Timekeeping System
« Reply #10 on: 11/03/2016 04:16 PM »
Those living on Mars would want a sunlight oriented system for sols like we have on Earth.  I think it's a bad idea to alter the second proportionately as some elsewhere have suggested.  Although not noticed by Mars residents it could complicate engineering calculations and be a source of error.

My radical Mars quirky solution is to use normal Earth hours minutes and seconds but at midnight when all but the night shift and those wild & crazy late night Mars party animals are asleep, have the clocks go to Red Time where the extra 39 minutes 35.244 seconds are added and counted down before resuming at say 12:01.  Mars sols are preserved.  Everyone in the inner solar system is using standard seconds, etc.  And a party time is enshrined in unique Mars culture.

      I played around with the number of seconds in a Mars Sol, working with Mars hours and Mars minutes, but overall, your's seems both the simplest and least problematic solution.  Almost having an additional 40 minutes of sleep per night would probably be welcome by any colonists, although it WILL cause some time synchronization issues with those on Earth.

      Now, what's your thoughts on a Mars Calendar?

      I'm thinking a 7 day week, (about 95.43 weeks a year) a 22 month year with 14 months with 30 days and 8 months with 31 days.  The odd bit at the end would be a Leap Day, to be used every couple of years or so.

      Naming the first ten days could use one through ten in Latin, with the other twelve months pretty much as January through December.

      Alternatively, you could have a year with 24 months, with about 95.5 weeks for the year, with 20 months having 4 weeks, for 28 days each having 4 weeks, and 4 months of 27 days each.  Thewy could be named First January, First February, etc. until First December, then start with Second January, Second February, etc.  This would keep the calendar to a fairly close approximation of the Earth calendar, adding a Leap Day to First February every so often to keep in approximate sync with Earth
« Last Edit: 11/03/2016 04:42 PM by JasonAW3 »
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Online guckyfan

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Re: Mars Timekeeping System
« Reply #11 on: 11/03/2016 04:25 PM »
Only the days adapted to the slightly different length of day.

???? Just use Martian days/years. Makes outside jaunts much easier - daylight matches the clock.

Maybe you missed this part of my suggestion? I would not suggest having the days divert from local daylight. Only the calendar as close as possible with the earth calender might be a good idea. To make up for the different length of day, occasionally the 31. of a month would need to be skipped.

Offline Jim

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Re: Mars Timekeeping System
« Reply #12 on: 11/03/2016 04:56 PM »
Those living on Mars would want a sunlight oriented system for sols like we have on Earth.  I think it's a bad idea to alter the second proportionately as some elsewhere have suggested.  Although not noticed by Mars residents it could complicate engineering calculations and be a source of error.

My radical Mars quirky solution is to use normal Earth hours minutes and seconds but at midnight when all but the night shift and those wild & crazy late night Mars party animals are asleep, have the clocks go to Red Time where the extra 39 minutes 35.244 seconds are added and counted down before resuming at say 12:01.  Mars sols are preserved.  Everyone in the inner solar system is using standard seconds, etc.  And a party time is enshrined in unique Mars culture.

How does that work for multiple time zones?  And for shift work?
« Last Edit: 11/03/2016 04:56 PM by Jim »

Offline CraigLieb

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Re: Mars Timekeeping System
« Reply #13 on: 11/03/2016 04:59 PM »
Those living on Mars would want a sunlight oriented system for sols like we have on Earth.  I think it's a bad idea to alter the second proportionately as some elsewhere have suggested.  Although not noticed by Mars residents it could complicate engineering calculations and be a source of error.

My radical Mars quirky solution is to use normal Earth hours minutes and seconds but at midnight when all but the night shift and those wild & crazy late night Mars party animals are asleep, have the clocks go to Red Time where the extra 39 minutes 35.244 seconds are added and counted down before resuming at say 12:01.  Mars sols are preserved.  Everyone in the inner solar system is using standard seconds, etc.  And a party time is enshrined in unique Mars culture.

This is nearly what the settlers did in the fictional Mars novels by Robinson.
It was considered a period where non-violent, but outside norms behaviors were tolerated or even encouraged.
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Offline baldusi

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Re: Mars Timekeeping System
« Reply #14 on: 11/03/2016 06:07 PM »
I certainly believe that the SI second should be used. This means that a sol should be defined as either 88,775s or 88,776s.
88,775s factors are 5^2*53*67. So you could have a 25 martian hour with 53 martian minutes of 67 seconds.
88,776s factors are 2^3*3^4*137. So you could have 24 hours, but with just 137 martian minutes of 27 seconds. I guess you could also have 137 martian hours of 9 martian minute of 72 seconds.
Btw, a 25hr of 59minutes of 60 seconds would be off by 275.25seconds/sol.


Offline biosehnsucht

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Re: Mars Timekeeping System
« Reply #15 on: 11/03/2016 10:12 PM »
Apparently some (all?) of our existing Mars rovers use 24 hour clocks with "slow" seconds so that they stretch 24h of onboard time to the actual length of a Sol. I guess this was easier to use existing hardware clocks that only understand earth time?

I think modifying the duration of a second, is a terrible idea. Basic units should mean the same thing, and if you need similar-but-different units, they should be called something else.

Similarly, I think trying to force the martian months to coincide with Earth months is a bad idea, as it will just lead to confusion, as they inevitably drift apart and have to be forced back together with weird calendar gymnastics. If you're communicating with someone on the other planet and make reference to something in january, is that Earth January , Mars First January, Mars Second January, .... ? They should have unique names so intent is clear.

Offline CuddlyRocket

Re: Mars Timekeeping System
« Reply #16 on: 11/04/2016 01:25 AM »
I agree that you don't want to mess with the definitions of the basic units of measurements used in science and engineering. That will cause all sorts of problems. (Obviously, meters and kilograms can stay the same magnitude, but just changing the unit of time changes the definition of a meter; not to mention the definitions of velocity, acceleration, force, current, etc.) But there's nothing to stop the development of Martian equivalents with some defined conversion factor. After all, both the US and UK use miles, but the mile is defined as 1,609.344 meters by international agreement. It would probably help avoid confusion if the local equivalents used different words - otherwise you'd need to talk about 'standard' and 'local' seconds etc.

Colonists on Mars are going to have a lot of new stuff to deal with, and it's important in such circumstances not to gratuitously change things that don't need to change. People are used to days of 24 hours and weeks of seven days etc, and I see no reason to change them or make things unnecessarily complicated. Plus, there are probably good, if unarticulated, reasons why we've settled on our time periods with attempts to change them failing. They seem to fit human nature, somehow!

It seems the use of 'sol' has already become established, so you could keep that and have sols of 24 local hours (or whatever you choose to call this time unit) divided into 60 local minutes etc. You could have a seven sol week with weekends. Call the days Monsol, Tuesol, Wednesol, Thursol, Frisol, Satsol and Sunsol! (Other language versions may be available!)

As for the year, I don't think people are going to be happy with a year that's nearly twice as long as it is now. It could cause all sorts of legal problems relating to age. For instance, at what age do Martian kids start school? There are already difficulties with the different levels of development of children with birthdays early in the school year compared with those who have birthdays at the end. Imagine if there was twice this difference in any school class? No, Martians would probably end up with some mechanism to divide the year into two, so it's probably better to build this in from the start. I'd divide the Martian orbital period into two calendar years. Each would then be 343.5 days long, which is about 6% shorter. (The age of majority on Mars would probably be 19, rather than 18!)

I don't think seasonal changes will be as important on Mars, where people will live in artificial environments, but you could refer to 'early' and 'late' years or somesuch, if felt desirable (though the years should be numbered consecutively). Divide each year into twelve 'months' with some appropriate number of sols in each (there's ~334.25 sols in such a year), remembering to keep the half and quarter-years as near the same length as possible - very important for commercial contracts and something often forgotten by Martian calendar creators! Throw in the odd leap day to keep things consistent over time.

Offline savuporo

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Re: Mars Timekeeping System
« Reply #17 on: 11/04/2016 04:28 AM »
While you all figure out the ever important mars calendars along with GPS constellations and other important details, such as BX ( Before SpaceX ) or Anno Elon is more appropriate way to start counting Sols once we get JPL out of the way, here are some functional Mars Timekeeping Systems

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Offline b0objunior

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Re: Mars Timekeeping System
« Reply #18 on: 11/04/2016 04:32 AM »
While you all figure out the ever important mars calendars along with GPS constellations and other important details, such as BX ( Before SpaceX ) or Anno Elon is more appropriate way to start counting Sols once we get JPL out of the way, here are some functional Mars Timekeeping Systems
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Offline savuporo

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Re: Mars Timekeeping System
« Reply #19 on: 11/04/2016 04:34 AM »
You're kidding right? I really hope so.
On an internet forum ? I would never
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Offline Stan-1967

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Re: Mars Timekeeping System
« Reply #20 on: 11/04/2016 06:17 AM »
Those living on Mars would want a sunlight oriented system for sols like we have on Earth.  I think it's a bad idea to alter the second proportionately as some elsewhere have suggested.  Although not noticed by Mars residents it could complicate engineering calculations and be a source of error.

My radical Mars quirky solution is to use normal Earth hours minutes and seconds but at midnight when all but the night shift and those wild & crazy late night Mars party animals are asleep, have the clocks go to Red Time where the extra 39 minutes 35.244 seconds are added and counted down before resuming at say 12:01.  Mars sols are preserved.  Everyone in the inner solar system is using standard seconds, etc.  And a party time is enshrined in unique Mars culture.

How does that work for multiple time zones?  And for shift work?

I think it could still work fine.  It would operate like "overtime" in any familiar sporting event you want to compare against.  The final 24th  hour of the day would not roll over at 60 minutes past the hour, but keep ticking away to 24h 99min &  35.244 seconds then it's becomes 1am.  This would be the case in every time zone. 

We accept some randomness in our definitions of time periods here on earth.   Every four years we have a leap year, where we alter the definition of a year from 365 days to 366 days.   Martians will do something like this every night.  On Mars, an hour is equal to 60 minutes, with the exception of the last hour of the day, which is equal to 99 minutes & 35.244 seconds.  If that's too messy, just call it any name your want, overtime, Red Time, purge time, etc., but define it as 39 minutes and 35.244 seconds, & don't roll over the clock to the next day until that time period is expired.

As for shift workers, just pay them by the minute.  I'm sure the unionized ones will find a way to slack off for that hanging chad of 35.244 seconds to keep the math simple.



Offline Bynaus

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Re: Mars Timekeeping System
« Reply #21 on: 11/04/2016 08:04 AM »
I don't think time-keeping on Mars would change much, certainly not initally. People would still feel comfortable counting in minutes (60 s each), hours (60 min each), days (of 24 hours and 38 minutes each) and weeks (7 days each). Machines will still expect seconds to be SI-seconds.

So I think nothing will really change much, except for the fact that there would be 668.6 sols in a martian year (which is an important cycle especially for a solar-powered colony, as this is the time horizon / cycle length over which energy storage and crop production has to be managed). It would feel most natural to just drop the month system (no "Moon" anyway...) and subdivide the year in weeks (of 7 days) instead of months, so you would simply have 95.5 weeks per (martian) year.

The half-week could be used for festivities, so that each year could start on the same day of the week. Then, your birth-date on Mars could simply be, say, Tuesday 49th, 23, meaning Tuesday of the 49th week in the 23rd year after the first landing.

Offline Jim

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Re: Mars Timekeeping System
« Reply #22 on: 11/04/2016 10:05 AM »

I think it could still work fine.  It would operate like "overtime" in any familiar sporting event you want to compare against.  The final 24th  hour of the day would not roll over at 60 minutes past the hour, but keep ticking away to 24h 99min &  35.244 seconds then it's becomes 1am.  This would be the case in every time zone. 

We accept some randomness in our definitions of time periods here on earth.   Every four years we have a leap year, where we alter the definition of a year from 365 days to 366 days.   Martians will do something like this every night.  On Mars, an hour is equal to 60 minutes, with the exception of the last hour of the day, which is equal to 99 minutes & 35.244 seconds.  If that's too messy, just call it any name your want, overtime, Red Time, purge time, etc., but define it as 39 minutes and 35.244 seconds, & don't roll over the clock to the next day until that time period is expired.
.


No,  it wouldn't.  It is 11pm and a person wants to have a telecon with groups in 3 different time zone in 200 minutes.   What time would that be in each time zone?
« Last Edit: 11/04/2016 10:05 AM by Jim »

Offline Jim

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Re: Mars Timekeeping System
« Reply #23 on: 11/04/2016 10:09 AM »

I think it could still work fine.  It would operate like "overtime" in any familiar sporting event you want to compare against.  The final 24th  hour of the day would not roll over at 60 minutes past the hour, but keep ticking away to 24h 99min &  35.244 seconds then it's becomes 1am.  This would be the case in every time zone. 


That is the wrong way to do, if you are going to have red time.   The last hour would be 23h 99min &  35.244 and then it becomes 0000h
« Last Edit: 11/04/2016 10:11 AM by Jim »

Online rsdavis9

Re: Mars Timekeeping System
« Reply #24 on: 11/04/2016 11:05 AM »
I think mars sols are good.
Keep "normal" hours, minutes, seconds.
martian years of martian sols.

Get rid of timezones. We only have timezones because we use to use the sun as our clock.
People get used to a time being a location specific sun condition. So it doesn't matter what it is as long as it stays the same day after day. So time of day starts for the prime mars meridian having the mean sun passing it. It ends when the mean sun makes 360 degrees of rotation. Just because mars doesn't have exactly 86400 seconds in it shouldn't matter.

So without timezones. Helas basin colonists would get used to 7:35 being sunrise. and 18:37 being sunset. Of course seasonal variations change that somewhat. Another location would have 23:53 as sunrise and 12:01 (the next day) as sunset.
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Offline Jim

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Re: Mars Timekeeping System
« Reply #25 on: 11/04/2016 11:21 AM »

So without timezones. Helas basin colonists would get used to 7:35 being sunrise. and 18:37 being sunset. Of course seasonal variations change that somewhat. Another location would have 23:53 as sunrise and 12:01 (the next day) as sunset.


That is impractical.  So when one travels to a different location, how would they know when the start of the day is?  When does work start or shops open?

Online rsdavis9

Re: Mars Timekeeping System
« Reply #26 on: 11/04/2016 11:31 AM »

So without timezones. Helas basin colonists would get used to 7:35 being sunrise. and 18:37 being sunset. Of course seasonal variations change that somewhat. Another location would have 23:53 as sunrise and 12:01 (the next day) as sunset.


That is impractical.  So when one travels to a different location, how would they know when the start of the day is?  When does work start or shops open?

Everytime I travel on earth work and shops change. So do the open/start times. So when doing a big move you get used to different times.
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Offline Jim

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Re: Mars Timekeeping System
« Reply #27 on: 11/04/2016 11:42 AM »


Everytime I travel on earth work and shops change. So do the open/start times. So when doing a big move you get used to different times.


You at least know it is 9 or 10am when they open

Online rsdavis9

Re: Mars Timekeeping System
« Reply #28 on: 11/04/2016 11:51 AM »
When I travel to california customer service reps start work at 7am or earlier so as to better serve east coast customers. When I go to work in the east coast work starts 8 or 9am.

Personally I hate am and pm. Gotten confused too many times. Timezones fall into the same class for me. Mass confusion about when something happens. I see questions on this forum numerous times saying that EST? what time is that in CET.

Ugh!
UTC is so much easier.
I have a good friend that everytime he traveled he would keep his watch set to EST(where he lives) and would just convert while away from home.

The last time I got bit by AM/PM was when I had a flight out of orlando back to boston. I printed out the boarding passes and never noticed the departure time was 7PM. So I got up early to get on a flight for what I thought was 7AM. Luckily the airlines let me get on a earlier flight with no fee instead of making me wait in the airport for 12 hours!

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Offline philw1776

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Re: Mars Timekeeping System
« Reply #29 on: 11/04/2016 11:54 AM »
Those living on Mars would want a sunlight oriented system for sols like we have on Earth.  I think it's a bad idea to alter the second proportionately as some elsewhere have suggested.  Although not noticed by Mars residents it could complicate engineering calculations and be a source of error.

My radical Mars quirky solution is to use normal Earth hours minutes and seconds but at midnight when all but the night shift and those wild & crazy late night Mars party animals are asleep, have the clocks go to Red Time where the extra 39 minutes 35.244 seconds are added and counted down before resuming at say 12:01.  Mars sols are preserved.  Everyone in the inner solar system is using standard seconds, etc.  And a party time is enshrined in unique Mars culture.

How does that work for multiple time zones?  And for shift work?

I may not understand the question, but as on Earth there would be multiple time zones, each using the same 24 Hr 39 minute system.

If you're on night shift, your digital clocks simply display Red Time for 39 minutes after 12 AM.  If the question is if they're paid per hour, do they get time and a half for those minutes, I dunno!
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Offline baldusi

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Re: Mars Timekeeping System
« Reply #30 on: 11/04/2016 02:20 PM »
Well, one interesting fact about Mars orbit is that it is more elliptical than Earth's. So, seasons have different lengths (194 to 142 max min). This also means that the difference between sideral and solar day varies with the year.
I'm wondering if this could be used to have "built in" time differences (like having certain days with 25hrs and some with 24hs) to keep the year right but both keep the martian year and the solar year closer to the solar cycle.

Online rsdavis9

Re: Mars Timekeeping System
« Reply #31 on: 11/04/2016 02:24 PM »
Well, one interesting fact about Mars orbit is that it is more elliptical than Earth's. So, seasons have different lengths (194 to 142 max min). This also means that the difference between sideral and solar day varies with the year.
I'm wondering if this could be used to have "built in" time differences (like having certain days with 25hrs and some with 24hs) to keep the year right but both keep the martian year and the solar year closer to the solar cycle.

Thats just the difference between mean sun and actual sun. The equation of time is what it is called. On earth it is 16min. On mars it is larger.
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Offline baldusi

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Re: Mars Timekeeping System
« Reply #32 on: 11/04/2016 03:23 PM »
Well, one interesting fact about Mars orbit is that it is more elliptical than Earth's. So, seasons have different lengths (194 to 142 max min). This also means that the difference between sideral and solar day varies with the year.
I'm wondering if this could be used to have "built in" time differences (like having certain days with 25hrs and some with 24hs) to keep the year right but both keep the martian year and the solar year closer to the solar cycle.

Thats just the difference between mean sun and actual sun. The equation of time is what it is called. On earth it is 16min. On mars it is larger.
You are assuming a constant radial velocity, which would keep the precession constant. On more elliptical orbits than Earth, the rate varies through the year, the difference is significant. This means days which are "longer" and "shorter". Not in the daylight sense but on the total length of the cycle (e.g. dawn to dawn).
May be that variance can be used to introduce leap hours to keep a more logical time system. I don't like to use prime numbers for hours, minutes and seconds.

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Offline philw1776

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Re: Mars Timekeeping System
« Reply #34 on: 11/04/2016 03:40 PM »
https://en.wikipedia.org/wiki/Equation_of_time#Explanations_for_the_major_components_of_the_equation_of_time

https://en.wikipedia.org/wiki/Analemma#/media/File:Mars_analemma.GIF

so the equation of time is about +- and hour.

Maybe the Martians will invent a system to deal with this.  Call it something, say like "Daylight Savings Time"  or somesuch? :)
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Offline ThereIWas3

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Re: Mars Timekeeping System
« Reply #35 on: 11/04/2016 04:37 PM »
I liked Jim's idea of stretching the last hour of the day rather than inserting a time-slip.  But then I realized that if this is combined with time zones it gets confusing again, as each time zone would be stretching an hour at a different global time.

How about say each hour consists of 61 minutes and 39 seconds?  24 such hours add up to the correct total, all hours are the same length everywhere on Mars, your computerized wristwatch does the math, and time zones are possible.   You would hardly notice the difference for most human activities.   But if you are timing a critical process, navigation, rocket launches, better just use units of seconds, just like the SI system is supposed to.   I remember in the "Orbiter" space simulation program, all timestamps are in seconds, so you get things like "Launch will be at 57,322.7 seconds"

Alternately, define the 'minute' to be a tiny bit longer, rather than the hour.  It works out the same.
« Last Edit: 11/04/2016 04:40 PM by ThereIWas3 »
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Offline Robotbeat

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Re: Mars Timekeeping System
« Reply #36 on: 11/04/2016 05:47 PM »
A mini party during the Red Time each night!
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Offline MP99

Re: Mars Timekeeping System
« Reply #37 on: 11/04/2016 06:54 PM »
How about a standard day of 24:40, then about every 25th day is 24:30 long?

Clocks would never get more than five minutes out of sync with the daylight cycle.

It does mean that on transition day, the hours in some time zones would be 10 minutes adrift until they also hit midnight.

That might also make for a natural "month" analogue - the last day of the "month" would be shorter. This would also make it easier for people to remember about the "leap" minutes. If today is the first, then westerly timezones which haven't yet reached midnight are 10 minutes behind. If tomorrow is the first, then easterly timezones which are past midnight are 10 mins ahead.

Unfortunately, months wouldn't fit into a year - much as Lunar months don't on earth.

Cheers, Martin

PS programmers would curse this scheme - makes for some nasty timezone and time difference calculations, with various conditionals.

Edit:mixed up east and west.
« Last Edit: 11/04/2016 06:59 PM by MP99 »

Offline mrhuggy

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Re: Mars Timekeeping System
« Reply #38 on: 11/04/2016 07:50 PM »
I actually did some work on this about 20+ years ago.

1 Martian Second = 1.025956010 Earth Second

60 Msec Per Minutes
60 Minutes per Hour
24 Hours per Day

Making the second slightly longer keeps things usable.

The Year would be split into 98  7 day weeks. This would leave you with 1 day which would be new years day.

So you would have a time looking like 12:28 Monday 89 2025
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Offline Paul451

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Re: Mars Timekeeping System
« Reply #39 on: 11/04/2016 11:43 PM »
I find it bizarre that people are trying to force some equivalent of weeks and months into the Martian year. Or even time-zones.

These are not medieval tenant farmers. They are highly educated, technologically equipped, first-world space colonists.

"How will you know when the stores open?" {sigh} Seriously? It's the 21st freakin' century.

--

It's worth noting that the calendar year on Earth came long after the development of weeks/months/seasons. Lunar calendars were more common initially (hence months). And every region generally used their own incompatible calendars. (Even seasons weren't standard.)

Likewise, time "zones" didn't exist, in any meaningful sense. There was only ever the time where you were, based on local noon. Ten miles down the road, the time would be different.

Every village kept its own time. Every ship used its local time, not the local time-zone. That is, they calculated local noon, they did not work out which 1/24th time-zone they were in. Railway schedules seem to have standardised regions into single "time-zones", which then led to global standardisation. (For very low values of "standard", when you look at an actual map.)

China copes with a single time-zone instead of the 4 or 5 they should be using. Russia mostly ignores 4 of their 11 time zones. The US military generally uses a single "time-zone" (GMT) globally to make communication easier.  The trend has been to collectivise local times into zones, not to divide them. And much of the wonkiness of the time-zone map is because of regions pushing themselves into neighbouring time-zones for commercial reasons, trade and communications mattering more than keeping track of local noon.

--

So looking at how Martian settlement would evolve: There would the site of the first colony. Most secondary sites would be close enough to the colony that they would just use the same time. Missions (such as science stations) at significant distance would likewise use the same standard colony time for convenience and communication. Hence there'd be one standard time-zone for the entire planet (and one standard Earth-time (GMT) that they'd compare that to.)

By the time there are enough large secondary colonies far enough away from the primary colony for local-noon to differ by more than a couple of hours, the Standard Mars Time created by that first colony site would be culturally entrenched. Secondary time-zones are unlikely to then be adopted due to the perceived disadvantages they create. (I mean, think about the ridiculousness of the International Dateline. Australian and US readers are on different days.)

Similarly, it would be silly to divide the Martian year into weeks/months. There's no pre-existing tradition of a Mars calendar, it would just be a clumsy arbitrary system to memorise. The first colony would just count sols, and that would become the tradition.

In fact, I'm not even convinced they'd bother to use the Martian year for a calendar. Again, these aren't medieval farmers. Mostly they'd use keep counting in Earth-years. You could even use Earth weeks, mostly. Even counting sols, you'd only lose 3 "days" every 109 sols. Ie, during a 16 weeks cycle, you need to have three short weeks and that keeps you in approximate sync with the Earth calendar.

[And if you were going to use anything other than Earth years, it would more likely be based around the Earth-Mars synod, which will be the most important cycle to colonists for decades, and thus the most likely to become "traditional". Nearly 760 sols/780 days. And by the time you have a large enough Martian population for the majority to no longer care about transfer orbits, it would have long since become traditional. Synod 50 rather than Mars-Year 56.]

Offline Robotbeat

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Re: Mars Timekeeping System
« Reply #40 on: 11/05/2016 12:06 AM »
Why is this in the SpaceX section?
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Offline RonM

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Re: Mars Timekeeping System
« Reply #41 on: 11/05/2016 12:55 AM »
Why is this in the SpaceX section?

I guess because at the moment SpaceX is the only group that might actually colonize Mars.

Offline Nomadd

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Re: Mars Timekeeping System
« Reply #42 on: 11/05/2016 01:23 AM »
"Stardate 2016309.22.....Mars Timekeeping System thread degenerates into free-for-all."
« Last Edit: 11/07/2016 10:33 PM by Nomadd »

Offline ChrisWilson68

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Re: Mars Timekeeping System
« Reply #43 on: 11/05/2016 02:13 AM »
My preferred solution: sols, mours, minutes, seconds, meeks, marths, and mears.

Minutes and seconds are as on Earth.  Sols are Martian days, as already used.  A mour is 1/24th of a sol.  A meek is 7 sols.  A marth is 30 or 31 sols.  A mear is a Martian year. One of the marths will have 30 sols on some mears and 31 on other mears.

Mours, meeks, marths, and mears are so named to avoid confusion with the Earth versions but to be similar enough to make it easy to remember what each means.

Why?  Well, sols are very useful because the day-night cycle is the most important regular time cycle to humans.  A mour as 1/24th of a sol is so timezones work out right.  Timezones have developed on Earth as a system that works pretty well.  But does  a mour need to be divided into exactly 60 of some unit?  Not really.  Minutes and seconds are often used to measure intervals of time, and there's good reason to keep these the same as on Earth.  A 5 minute limit in a video game or a 20 minute timer for cooking would be the same as on Earth.  It has the disadvantage that it's a little harder to figure out what time is 100 minutes from now, but then again that's not terribly simple for some people using Earth time, and not something that comes up all the time.

A meek as 7 sols is useful because over thousands of years, human civilization has adapted a cycle of 7 day-night cycles as a work-rest pattern.  Why this instead of the 28 of a lunar cycle?  Maybe it's just random, but I think there's a good chance it's because a cycle of 7 day-night cycles tends to work out fairly well for humans.  Even if there's nothing inherently good about having a weekend every 7 day-night cycles, it's part of the culture of the first colonists and it will help them feel more at home.  During the French Revolution, they tried to replace 7-day weeks with 10-day weeks as they were replacing other units with the metric units.  The metric system was successful, 10-day weeks, not so much.

The marth is the one whose utility I'm least convinced of.  But we have kept using months on Earth for 2,000 years after ithey became detached from the lunar cycle they started from.  It might be because there's some utility in it.  We don't really have much of our daily life revolving around months as we do with days and weeks, but it's a convenient way of partitioning the year into memorable chunks.  We have images that come to mind when we think of August or February.  It might be easier to think of what part of the year we're in when we have names for 30-or-so day-night cycle chunks than just using numbering within the year.

And the mear is a useful measure because it corresponds to the biggest climate cycle.  Though I can also see the argument for the synod for as long as contact with Earth is important (i.e. a very long time).

In writing, instead of 8:04pm 11/4/2016, you'd have something like 22:04mt 11/4/2016md where the mt is Mars Time and md is Mars Date.  That helps avoid confusion between Earth dates and times and Mars days and times.

People on Mars would also commonly use the Earth year for some purposes, I think.  It's too deeply embedded in our culture.  We think in terms of ages in years.  And, for a long time, people will be aware of the current Earth date a lot of the time simply because they'll commonly be consuming media from Earth.

Offline Stan-1967

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Re: Mars Timekeeping System
« Reply #44 on: 11/05/2016 03:09 AM »
Lots of interesting points in this thread.
1.  Time zones present difficult complications for coordinating events planet wide on Mars, & are a historical construct colonists could leave behind.

2.  Mars colonists will likely assign importance to time intervals not related to earth weeks or years.  I agree with the synod observation, just as military enlistees may count the days to their release.   

2A.  Another possibly better analogy for guidance would be to look at how people stationed in Antarctica lend relevance to time.  24 hr daily cycles are important for biological reasons, but when it's 6 month long dark winter "night", they probably just count days & think about when it gets light again, & when do the re-supply planes start landing.





Online GORDAP

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Re: Mars Timekeeping System
« Reply #45 on: 11/05/2016 03:23 AM »
I think Mars timekeeping standards give a unique opportunity to correct some of the things we currently do wrong on Earth, due simply to historical accident.

My recommendations for 'corrections':

1) Get rid of AM/PM.  'Military' time only.  The first hour is '0', not '12'.
2) Make all months the same number of days (sols).
3) Make each month an integral number of weeks.  For Earth, this would best be done as 4 weeks per month, and switch to having 13 months.  Leftover days (for Earth this would normally be 1 day, sometimes 2), would be placed at the end of the year after the last month and would just be 'Leap Days'.  They would all be 'Sundays' (the last day of the week, see #6 below), i.e., they wouldn't advance the day of the week.  Then the new year starts on Monday every year.
4) Make each month start off at the start of a week.  Taking numbers 3 and 4 together means we just don't need calendars anymore.  The Nth day of the month, every month, forever, would be the same day of the week.
5) Get rid of timezones.  We'd all be better off if we just switched to UTC on Earth (Jim's objections notwithstanding).  Oh, and without timezones, 'daylight savings time' makes no sense.  Jettison it as well.
6) While we're at it, make the first day of the week 'Monday', so those two days we call the 'weekend' are actually at the end of each week.

Mars Specifics:
A) Keep a standard 'second'.  The second is sacrosanct.
B) Keep a minute defined to be 60 seconds, and an hour to be defined as 60 minutes.
C) Have 'hour 24' consist of 39 minutes and 35 seconds.  Then hour 0 starts.  I slightly prefer this to Jim's solution of having hour 23 have an extra 39 minutes and 35 seconds.
D) Retain a 7 day week (I think this is pretty culturally ingrained).
E) So, to follow #s 3 and 4, above, we have to decide how many weeks per month, and the number of months.  It looks like the best would be 5 weeks per month and 19 months.  (This leaves I think 5, sometimes 6 'leap days' as defined above?)
F) I'd suggest month names of Manuary, Mebuary, Arch, Mapril, Ay, Mune... Mecember, plus 7 more new month names.
G) On the last 'leap day' each year, adjust for the built up leap seconds from rounding off the seconds of each sol.
H) Manuary 1st (Day 0) of Year 0 will be defined to be the exact day a human first sets foot on Mars.  (Unfortunately we are forever stuck with the mathematically confusing fact that we have no year 0 on Earth - we go from -1 to 1.)

Summary:

Keep the second, minute, hour and week as defined on Earth.

Let technology correct for the raggedy bits (extra partial hour each day, leap seconds at end of year) in an unobtrusive way.

Make several common sense improvements compared to present Earth systems.
« Last Edit: 11/05/2016 03:29 AM by GORDAP »

Offline colbourne

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Re: Mars Timekeeping System
« Reply #46 on: 11/05/2016 03:23 AM »
I really hope we have just one time zone for the whole of Mars. It will make everything much simpler, and I know this from experience, having written software to organise meetings across different time zones.

I suggest, as have many others, keeping seconds , minutes and hours the same as on Earth. It would be fun to have Mars months of a combination of  30 and 31 Mars days, with new Mars relevant names. The year would begin on the shortest day of where the first human base is established, probably using the first human landing as year 0.

All communications with Earth would use Earth dates and time (UTC).

Offline ChrisWilson68

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Re: Mars Timekeeping System
« Reply #47 on: 11/05/2016 06:40 AM »
Lots of interesting points in this thread.
1.  Time zones present difficult complications for coordinating events planet wide on Mars, & are a historical construct colonists could leave behind.

I disagree.  Timezones aren't "historical constructs".  The reasons they were created are the same reasons we still use them and the same reasons people on Mars will use them.

They were created so that the same time labels all over the world apply to the same parts of the day.  People can travel all over the world and know when it's noon, the sun will be approximately overhead.  They'll know the sun will come up sometime around 6:00am and set sometime around 6:00pm.  It's not always the same, but the best we can reasonably do while being able to easily keep track of what time it is for different people in different places and have nearby people using the same time as us.

Timezones are brilliant solutions to difficult problems.  They are problems we have today just as much as we had them when they were developed.  People shouldn't be so quick to dismiss them as relics of the past that aren't relevant in today's world.

2A.  Another possibly better analogy for guidance would be to look at how people stationed in Antarctica lend relevance to time.  24 hr daily cycles are important for biological reasons, but when it's 6 month long dark winter "night", they probably just count days & think about when it gets light again, & when do the re-supply planes start landing.

I don't think Antarctica is a good analog for Mars as far as timekeeping goes.  Mars has a light-dark cycle that is close to 24 hours.  And it has a whole continuum of places where midday light is shifted by a constant factor from that in any given reference region.  As far as timekeeping goes, most of Mars is much more like most of Earth than either is like the polar regions of either planet.

Offline ChrisWilson68

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Re: Mars Timekeeping System
« Reply #48 on: 11/05/2016 06:58 AM »
I think Mars timekeeping standards give a unique opportunity to correct some of the things we currently do wrong on Earth, due simply to historical accident.

My recommendations for 'corrections':

1) Get rid of AM/PM.  'Military' time only.  The first hour is '0', not '12'.

I agree with you on that one.

2) Make all months the same number of days (sols).

There are good reasons to have months that are different numbers of days.  It allows you to have them come in the same place in every year without the lengths of the units being limited to factors of the number of days in a year.

3) Make each month an integral number of weeks.  For Earth, this would best be done as 4 weeks per month, and switch to having 13 months.  Leftover days (for Earth this would normally be 1 day, sometimes 2), would be placed at the end of the year after the last month and would just be 'Leap Days'.  They would all be 'Sundays' (the last day of the week, see #6 below), i.e., they wouldn't advance the day of the week.  Then the new year starts on Monday every year.

This just replaces one oddity with another one.  I don't believe it's an improvement.  Having some days that aren't in any month and some days that aren't in any week is a far more serious problem than having years and months begin on different days of the week, or months with small variations in length.  It means, for example, that if you have something that you want done exactly once every 7 days, you can't just have it on the same day of the week indefinitely.  It means you have to think carefully and do special calculations to see how many days away the Friday 8 weeks from today is.  And there are many more issues.

4) Make each month start off at the start of a week.  Taking numbers 3 and 4 together means we just don't need calendars anymore.  The Nth day of the month, every month, forever, would be the same day of the week.

But it causes more severe problems as I mentioned above.

5) Get rid of timezones.  We'd all be better off if we just switched to UTC on Earth (Jim's objections notwithstanding).

Timezones are great!  They let us travel without having to re-learn what times mean what parts of the day.

Oh, and without timezones, 'daylight savings time' makes no sense.  Jettison it as well.
6) While we're at it, make the first day of the week 'Monday', so those two days we call the 'weekend' are actually at the end of each week.

There's no commonly-agreed-on convention about which day of the week the week "begins" on.  And there's really no need.

Mars Specifics:
A) Keep a standard 'second'.  The second is sacrosanct.
B) Keep a minute defined to be 60 seconds, and an hour to be defined as 60 minutes.

That breaks a lot of the utility of timezones -- making it easy to figure out what time it is there when it is a particular time here.

C) Have 'hour 24' consist of 39 minutes and 35 seconds.  Then hour 0 starts.  I slightly prefer this to Jim's solution of having hour 23 have an extra 39 minutes and 35 seconds.
D) Retain a 7 day week (I think this is pretty culturally ingrained).
E) So, to follow #s 3 and 4, above, we have to decide how many weeks per month, and the number of months.  It looks like the best would be 5 weeks per month and 19 months.  (This leaves I think 5, sometimes 6 'leap days' as defined above?)
F) I'd suggest month names of Manuary, Mebuary, Arch, Mapril, Ay, Mune... Mecember, plus 7 more new month names.
G) On the last 'leap day' each year, adjust for the built up leap seconds from rounding off the seconds of each sol.

That will cause more pain for computer systems than just putting the fractional seconds in the sols themselves.  The more unevenness in the lengths of days, the worse it is.  It's bad enough week get a leap second every once in a while, your scheme of saving them up and adding a bunch of them in one day would be much worse.

Online guckyfan

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Re: Mars Timekeeping System
« Reply #49 on: 11/05/2016 07:36 AM »
1) Get rid of AM/PM.  'Military' time only.  The first hour is '0', not '12'.

As a european I don't have problems with am/pm.

But 12 pm as noon, not midnight, is an absurdity.

Offline Paul451

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Re: Mars Timekeeping System
« Reply #50 on: 11/05/2016 03:37 PM »
My preferred solution: sols, mours, minutes, seconds, meeks, marths, and mears.
E) So, to follow #s 3 and 4, above, we have to decide how many weeks per month, and the number of months.  It looks like the best would be 5 weeks per month and 19 months.  (This leaves I think 5, sometimes 6 'leap days' as defined above?)
F) I'd suggest month names of Manuary, Mebuary, Arch, Mapril, Ay, Mune... Mecember, plus 7 more new month names.
G) On the last 'leap day' each year, adjust for the built up leap seconds from rounding off the seconds of each sol.

See how quickly you ended up with a convoluted hack?

For Mars, you'd be better off avoiding months entirely and just counting sols within the Martian year. Remembering 19 month names is no more useful than remembering that the early 400's is the start of winter, or that the 200's are dust-storm season and you have to prepare for occasional power rationing and generally schedule more guys for clean-up EVAs; or that you need to get low priority comms with Earth done by 340, 345 at the latest, because this year Earth is in solar-conjunction between 348-351 and comms is relay-only.

IMO, colonists will use the standard Julian Earth calendar for 90% of long term planning and time-tracking. I doubt there will ever be an elaborate and unique "Martian" dating system; likewise counting Martian Years as part of the date; likewise counting your age in Mars years. Years will be counted by the Earth standard, the current date is whatever it is on Earth. Not 33/17/247, the 33rd day of the 17th month, MarsYear 247, which is your 35th MarsBirthday and the year of your retirement...

Of course the date of Mars settlement will be an anniversary date, just like Independence Day in the US, or any "Founders Day" of any former colony on Earth. But the US doesn't have it's own calendar, it just occasionally celebrates big round numbers like the bicentenary. In 1976, not Year200US. There will not be a MarsYear 0.

Yes, they'll keep track of the part of day (or sol) they are in, for obvious local convenience, and I suspect they'll keep some track of the number of sols in the Martian year, and the synod. But that's it. There'll be no "Martian calendar" as such.

I get the nerd-appeal of creating calendars, I'm even a fan of the 13 month universal calendar, but it is neither necessary nor desirable on Mars.
« Last Edit: 11/05/2016 03:56 PM by Paul451 »

Offline Paul451

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Re: Mars Timekeeping System
« Reply #51 on: 11/05/2016 03:41 PM »
1.  Time zones present difficult complications for coordinating events planet wide on Mars, & are a historical construct colonists could leave behind.
I disagree.  Timezones aren't "historical constructs".  [...]
They were created so that the same time labels all over the world apply to the same parts of the day.

For most of history there was no such thing as "time zones", the time was always based on immediate solar time. Ten miles down the road, the time would be slightly different. Every village had their own time. The combination of better clocks and increased speed of transport meant that coordinating between regions became harder, so regional time was created. (Historically, train timetables played a big role in that. Communities would gradually adopted nearby train-time as their local time, even if it was 10-30 minutes away from true solar time. According to wiki, Great Western was the first railway company to create a uniform time zone within their network.)

That led to "time zones" in different countries and regions within countries. But not the current nearest-hour system. Local time zones were still based on some previous local point, so neighbouring countries might be something random, like 47 minutes apart. The push to make it more uniform didn't really start until 1900 and took 30 years. (We still haven't truly adopted the uniform time-zone system. You just need to look at a map of actual time zones. It's a horrible mess.)

Likewise...

12 pm as noon, not midnight, is an absurdity.

Historically, the local day could start at sunrise, sunset, noon or midnight, depending on local custom. Solar zenith, noon, could be the seventh hour, the first, or the twelfth. (You see the remnants of this in many religious customs, where a holy day goes from sunset on one day to sunset on the next.)

Midnight doesn't have to be the start of the local day, "12" doesn't have to be when the sun is at local zenith (give or take). People have adopted a wide variety of systems and coped perfectly well.

As I said earlier, for decades after permanent settlement begins, the local time of the first colony site will be the most important "clock" to keep track of. (And for a long time, even that will run second to Earth's UTC.) Research and supply stations scattered at significant distances will still use "Colony Time", just as the US military uses UTC, and for the same reasons. And IMO, by the time there are major secondary settlements more than a few hundred kilometres away from the first colony, that single universal Colony Time will be so entrenched that the idea of introducing different time-zones will seem bizarre. The negatives will be seen as outweighing any possible convenience of a separate clock based on local-noon.

It's different on Earth. Adapting to a single global time would be chaos, we can't even finish the change to the existing time-zones. But on Mars, they'll start with universal planetary time. Introducing time zones would be the thing that causes confusion and is resisted.

Online guckyfan

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Re: Mars Timekeeping System
« Reply #52 on: 11/05/2016 04:02 PM »
12 pm as noon, not midnight, is an absurdity.

Historically, the local day could start at sunrise, sunset, noon or midnight, depending on local custom. Solar zenith, noon, could be the seventh hour, the first, or the twelfth. (You see the remnants of this in many religious customs, where a holy day goes from sunset on one day to sunset on the next.)

None of these can justify 1 pm follow 12 pm.

Offline Stan-1967

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Re: Mars Timekeeping System
« Reply #53 on: 11/05/2016 04:26 PM »
"Stardate 2016309.22.....Mars Timekeeping System thread degenerates into free-for-all.

3 pages into this thread, I think the first interplanetary war will start when the Imperial Martian ambassador to Earth misses his meeting with United Nations Proconsul to the Main Belt mining colonies.  All because he didn't compensate his mars time zone clock at His Olympus Mons chateau with against the clock of the main colony at Hellas Basin.

And it will be the fault of everyone here.....
« Last Edit: 11/07/2016 10:20 PM by Stan-1967 »

Offline ThereIWas3

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Re: Mars Timekeeping System
« Reply #54 on: 11/05/2016 04:35 PM »
Why is this in the SpaceX section?

Because this forum is organized by launcher hardware, not by destination.  If there was a "Mars" top level category independent of how you got there, or on whose rocket, this would belong there.
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Offline mark_m

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Re: Mars Timekeeping System
« Reply #55 on: 11/05/2016 04:55 PM »
It seems like if we want to keep the second unmodified (a necessity IMHO) AND have timezones that make sense, you have to either modify the number of seconds in a minute or the number of minutes in an hour.

My thought is a minute should be defined as 59 seconds. (Alternatively you could define an hour as 59 minutes.) Then there would be 25 hours a day of 60 minutes each, all minutes and seconds would match up at all times in all timezones, and the second doesn't need to be changed.

If I've calculated it correctly, that's only about a second off each day from an exact sol. Perhaps midnight at the Mars equivalent of GMT once a year there could be a few minutes of adjustment to bring the clock back in line with the sun.

[Edit to switch preference to 59 second minute.]
« Last Edit: 11/05/2016 05:22 PM by mark_m »

Offline CuddlyRocket

Re: Mars Timekeeping System
« Reply #56 on: 11/05/2016 06:25 PM »
It seems like if we want to keep the second unmodified (a necessity IMHO) AND have timezones that make sense, you have to either modify the number of seconds in a minute or the number of minutes in an hour.

Or create new units that perform the same function. We already have sols instead of days, so instead of hours, minutes and seconds, have ores, lepta and defterolepta (those are greek equivalents - I think - but you could have something else!). Granted, you then have two units for the same thing, but those of us in the UK or US and elsewhere are used to this. I can quite happily deal in meters and yards, miles and kilometers, pounds and kilograms, pints and liters and acres and hectares. Which I use depends on the context - liters to buy milk from the supermarket, pints to buy beer in my local! So, for daily life on Mars, you'll probably use ores and lepta (or whatever) and for science and engineering, the second and other SI units.

People aren't going to use the 24-hour clock like the military. We could do that now, and often do for train times etc. But we don't. People prefer to keep the am/pm distinction. So, unless you're going to criminalise people on Mars for answering six instead of 18 to 'what's the time?', I expect it will continue. And people will want a whole, preferably even number of time units in a sol. Who wants to do complex mental arithmetic to work out what half a day is?

Offline Paul451

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Re: Mars Timekeeping System
« Reply #57 on: 11/05/2016 07:53 PM »
so instead of hours, minutes and seconds, have ores, lepta and defterolepta

Gak. If you're going to change the fundamental units, why copy the base-12/base-60 conventions from Babylonian time?

Just use decimal fractions of sols. Half way through the day is 0.5. Each thousandth is nearly 90 seconds, each hundredth is nearly 15 minutes, each tenth almost 2.5hrs, so quick'n'dirty conversion isn't difficult.
« Last Edit: 11/05/2016 07:53 PM by Paul451 »

Offline Oersted

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Re: Mars Timekeeping System
« Reply #58 on: 11/05/2016 08:27 PM »
I really hope they will use a logical regular calendar, such as the proposed International Fixed Calendar that we OUGHT to use here on Earth...

https://en.wikipedia.org/wiki/International_Fixed_Calendar
"The several advantages of The International Fixed Calendar are mainly related to its organization.
-  Every year has exactly 52 weeks divided in 13 months.
-  Each month has exactly 28 days divided in 4 weeks.
- The calendar is the same every year (perennial), unlike the annual Gregorian calendar, which differs from year to year. Hence, scheduling is easier for institutions and industries with extended production cycles.
- Every day of the month falls on the same weekday in each month—the 17th always falls on a Tuesday, for example."





« Last Edit: 11/05/2016 08:27 PM by Oersted »

Offline ThereIWas3

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Re: Mars Timekeeping System
« Reply #59 on: 11/05/2016 09:59 PM »
And every month has a Friday the 13th.  :)
"If you want to build a ship, don’t drum up people to collect wood and don’t assign them tasks and work, but rather teach them to long for the endless immensity of the sea" - Antoine de Saint-Exupéry

Offline Paul451

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Re: Mars Timekeeping System
« Reply #60 on: 11/05/2016 10:09 PM »
The 13 month calendar works on Earth because 7*4*13 is 364 days, only one day off 365, close enough to be workable.

But the closest you can get on Mars is 7*5*19, which is still 5 sols away from a Martian year. You end up with a very clumsy calendar.

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Re: Mars Timekeeping System
« Reply #61 on: 11/05/2016 10:21 PM »
On Earth with this calendar, we'd have 1, sometimes 2 'leap days' at the end of the year.  This just gives one a looong weekend, which is just fine, and kind of lends itself to a natural 'New Years's extended holiday.

Sure, on Mars this comes out to 5, sometimes 6 extra days, but I don't think anyone would complain.  After all, the 'year' is a lot longer, so I'm sure the Martians would appreciate a nice 7 or 8 day weekend break before launching into the new year. 

Small price to pay for the nice, rational 'Fixed Calendar'.  Actually (for Earth or Mars), such a natural year ending holiday would be a feature, not a bug, in my book.


Offline Paul451

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Re: Mars Timekeeping System
« Reply #62 on: 11/05/2016 10:27 PM »
Surely the most "fixed" calendar is simply to count the sols.

Offline mark_m

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Re: Mars Timekeeping System
« Reply #63 on: 11/05/2016 10:34 PM »
Surely the most "fixed" calendar is simply to count the sols.

This seems reasonable, especially in technical applications. However, in the same way that timezones allow the various hours to correspond to traditional times of day (noon is about midday, 6 or so is sunrise, etc.) as Jim commented, the months do the same for the time of the year. Why not just have the same twelve months, just make them 57 or 58 sols long? That way, March would still mean the beginning of spring, August the middle of summer, etc.

[Edit days reference to sols.]
« Last Edit: 11/06/2016 12:55 AM by mark_m »

Offline Ludus

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Re: Mars Timekeeping System
« Reply #64 on: 11/06/2016 01:49 AM »
http://chapters.marssociety.org/usa/oh/zubrin/Zubrin.html
Zubrins

https://en.m.wikipedia.org/wiki/Darian_calendar
Darian

https://en.m.wikipedia.org/wiki/Timekeeping_on_Mars
Mars timekeeping conventions

https://en.m.wikipedia.org/wiki/Astronomy_on_Mars
Astronomical observation from Mars.

If I was going to live on Mars I'd prefer a calendar year based on the Mars-Earth Synodic cycle rather than Mars' orbit around the sun. That's 780 days so only about a hundred days longer, though that's based on earth days. The Mars sol concept as a basis for a day seems reasonable. I just don't see a justification from a colonist's pov to base a year on a Mars' solar year instead of a synod. That's fine for academics living on earth and is an obvious choice, but seems out of synch with what would matter to the lives of Martians living with the calendar day to day.

On earth it makes total sense that the relevant cycle of seasons that dominates people's lives be the basis of the calendar. On Mars it seems like the Mars solar orbit would be less important to people living there than the Mars-Earth synodic cycle. That's what would dictate holidays and determine the rhythm of life. Nobody is planting based on seasonal cycles or experiencing weather. Everybody is planning their life around the next wave of ships arriving and departing and the waxing and waning of communications latency.

The Martian Calendar shouldn't be arbitrarily imitative of what's important to people on Earth. This would be a "year" based on a physical orbital cycle, just not on Mars' Solar orbit, which would be less relevant to the lives of humans living there.

Numbers for a Martian Synodic Year Calendar:

The conversion is about 1.0274 days/sol (Earth days to Mars days).

So a Synod which is about 780 earth days is about 759.1 Sols.

This could allow 27.1 Martian months of 28 Sols each per Synodic year. So 27 months of a perfect 28 sols each, synched to the days of the week evenly plus a few festival days left over to even out the Synodic year (which might be styled as a very short 28th month.)

There is a pleasant symmetry in having a "year" contain as many months as a month has days, having months that are all even units (except for the last), having the days of the week synched with months and having the whole cycle reflect the orbital period that defines the coming and going of physical contact with earth which would dominate people's work and emotional lives.
« Last Edit: 11/06/2016 02:37 AM by Ludus »

Offline mark_m

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Re: Mars Timekeeping System
« Reply #65 on: 11/06/2016 02:13 AM »
If I was going to live on Mars I'd prefer a calendar year based on the Mars-Earth Synodic cycle rather than Mars' orbit around the sun.
That's a very interesting thought. Things to consider though: It'll certainly be a major factor for many decades at least, but how long until advances reduce the importance of the synod cycle? Similarly, how long before the Mars society isn't focused around the arrival of ships from Earth?

However, it may be true that the colonists won't care about the Martian seasons. I was just thinking of how the rovers have had to hunker down for the winter and assuming that they would have an impact on people's lives as well.

Offline Ludus

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Re: Mars Timekeeping System
« Reply #66 on: 11/06/2016 02:22 AM »
If I was going to live on Mars I'd prefer a calendar year based on the Mars-Earth Synodic cycle rather than Mars' orbit around the sun.
That's a very interesting thought. Things to consider though: It'll certainly be a major factor for many decades at least, but how long until advances reduce the importance of the synod cycle? Similarly, how long before the Mars society isn't focused around the arrival of ships from Earth?

However, it may be true that the colonists won't care about the Martian seasons. I was just thinking of how the rovers have had to hunker down for the winter and assuming that they would have an impact on people's lives as well.

I'd think it would dominate completely for many centuries. Only on a terraformed Mars that had weather and seasons that mattered to people would there be competition from the Solar year for priority.

Offline Hyperion5

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Re: Mars Timekeeping System
« Reply #67 on: 11/06/2016 06:11 AM »
People aren't going to use the 24-hour clock like the military. We could do that now, and often do for train times etc. But we don't.

Who are these people you speak of?  I've lived in Germany and traveled to much of Europe, where practically everything runs on 24-hour time, although a 12-hour clock is still more often used in colloquial conversation.  At last glance 24-hour time is used to varying degrees in Germany, Austria, Switzerland, Belgium, France, the Netherlands, Norway, Denmark, Sweden, Finland, the UK, Ireland, Italy, Poland, Spain, Portugal, Serbia, Turkey, South Korea, Japan, Australia, Cyprus, Czechia, Brazil, South Africa, Thailand (also uses 6-hour clock), Bahrain, Pakistan, and others.  India, Colombia, the US, Canada, and the Philippines are countries where 24-hour time is rarely used outside the military.  It doesn't seem like adjusting to a 24-hour clock is all that hard given its widespread use, sometimes even in colloquial speech. 


People prefer to keep the am/pm distinction. So, unless you're going to criminalise people on Mars for answering six instead of 18 to 'what's the time?', I expect it will continue. And people will want a whole, preferably even number of time units in a sol. Who wants to do complex mental arithmetic to work out what half a day is?

No one's going to criminalize anything, it's just that 24-hour time makes a lot of sense.  Obviously it's going to need some adjusting however, since we need to stuff more seconds into each hour.  A Martian Hour would therefore consist 3,698.9675 seconds in 60 Martian Minutes.  Each Martian Minute would consist of 61.649 seconds, while the SI second would be left as is.  This would probably be a good compromise at doing an early Martian timekeeping system. 





Offline Hyperion5

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Re: Mars Timekeeping System
« Reply #68 on: 11/06/2016 06:23 AM »
so instead of hours, minutes and seconds, have ores, lepta and defterolepta

Gak. If you're going to change the fundamental units, why copy the base-12/base-60 conventions from Babylonian time?

Just use decimal fractions of sols. Half way through the day is 0.5. Each thousandth is nearly 90 seconds, each hundredth is nearly 15 minutes, each tenth almost 2.5hrs, so quick'n'dirty conversion isn't difficult.

Decimal Timekeeping has already been done on Earth, but it never divided up the day as you have suggested.  Instead each day consists of 10 hours, each hour consists of 100 minutes, and each minute consists of 100 seconds.  It makes calculating fractions of the day dirt-simple and you can easily have time zones.  Although it never caught on it does make a lot of sense. 

Offline Paul451

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Re: Mars Timekeeping System
« Reply #69 on: 11/06/2016 11:44 AM »
Decimal Timekeeping has already been done on Earth, but it never divided up the day as you have suggested.

Swatch company tried to introduce "Swatch time", which was based on 1000th of a day.

Instead each day consists of 10 hours, each hour consists of 100 minutes, and each minute consists of 100 seconds.

That kind of stupidity is precisely what I'm trying to avoid. Blindly mimicking hours/minutes/seconds. It's the kind of thing the metric system was intended to eliminate. Different countries (or parts of a country, or trades within a country) using different length feet or miles, different sized ounces or pounds, etc. "New Seconds", "Mars Seconds". Blah.

(IMO, one of the worst mistakes in the metric system was deci/deca/centi/hecta prefixes, in order to create sub-units sort-of/kind-of similar to imperial units, giving in to the urge to mimic those old units. Centimetre, which is not even close to an inch. Decilitres, nearly but not three fluid ounces. Hectare, nothing like an acre. Hectapascal, which.. okay, it is a millibar, but still, blah, blah I say.)

[Edit: All of that said, it is interesting how easily the mission operators at NASA adopted a Mars clock by changing the length of the second, and hence minute/hour, even though the second is a metric unit, scientifically important.]
« Last Edit: 11/06/2016 11:52 AM by Paul451 »

Offline Paul451

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Re: Mars Timekeeping System
« Reply #70 on: 11/06/2016 11:45 AM »
Surely the most "fixed" calendar is simply to count the sols.
This seems reasonable, especially in technical applications. However, in the same way that timezones allow the various hours to correspond to traditional times of day (noon is about midday, 6 or so is sunrise, etc.) as Jim commented, the months do the same for the time of the year. Why not just have the same twelve months, just make them 57 or 58 sols long? That way, March would still mean the beginning of spring, August the middle of summer, etc.

How would that not apply to a simple sol-count? Remembering that winter starts around Sol 400, etc, is easier to remember than the kind of arbitrary calendars proposed so far.

If I was going to live on Mars I'd prefer a calendar year based on the Mars-Earth Synodic cycle rather than Mars' orbit around the sun.
That's a very interesting thought. Things to consider though: It'll certainly be a major factor for many decades at least, but how long until advances reduce the importance of the synod cycle? Similarly, how long before the Mars society isn't focused around the arrival of ships from Earth?

By which time it is a tradition, around which the Mars culture has evolved, hence very hard to shift.

Offline Jim

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Re: Mars Timekeeping System
« Reply #71 on: 11/06/2016 12:24 PM »

So a Synod which is about 780 earth days is about 759.1 Sols.


Synod is not applicable.  Musk intends to use fast transit which negates the need to launch at that specific time.

Offline Hyperion5

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Re: Mars Timekeeping System
« Reply #72 on: 11/06/2016 03:43 PM »
Decimal Timekeeping has already been done on Earth, but it never divided up the day as you have suggested.

Swatch company tried to introduce "Swatch time", which was based on 1000th of a day.

Instead each day consists of 10 hours, each hour consists of 100 minutes, and each minute consists of 100 seconds.

That kind of stupidity is precisely what I'm trying to avoid. Blindly mimicking hours/minutes/seconds. It's the kind of thing the metric system was intended to eliminate. Different countries (or parts of a country, or trades within a country) using different length feet or miles, different sized ounces or pounds, etc. "New Seconds", "Mars Seconds". Blah.

Given the distances involved, there is no way to have near-instantaneous communication with Earth, nor to have large scale trade.  Thus the barriers to implementing a more Mars-centric timekeeping system are not especially high. 


(IMO, one of the worst mistakes in the metric system was deci/deca/centi/hecta prefixes, in order to create sub-units sort-of/kind-of similar to imperial units, giving in to the urge to mimic those old units. Centimetre, which is not even close to an inch. Decilitres, nearly but not three fluid ounces. Hectare, nothing like an acre. Hectapascal, which.. okay, it is a millibar, but still, blah, blah I say.)

[Edit: All of that said, it is interesting how easily the mission operators at NASA adopted a Mars clock by changing the length of the second, and hence minute/hour, even though the second is a metric unit, scientifically important.]

I don't think you'll find many people who believe the prefix system in metric is a mistake.  It certainly hasn't hurt its worldwide acceptance, which increasingly is trending towards the US being the sole holdout against it and its prefix system.  With regards to the adoption of a Mars clock by NASA, it doesn't shock me, as some form of timekeeping adaptation will be needed.  I'd advocate keeping the SI second as is but simply modifying the minute or the hour for Mars local use. 

Offline Robotbeat

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Re: Mars Timekeeping System
« Reply #73 on: 11/06/2016 06:01 PM »

So a Synod which is about 780 earth days is about 759.1 Sols.


Synod is not applicable.  Musk intends to use fast transit which negates the need to launch at that specific time.
While true, launches ARE still going to be clustered around the Mars launch window.

I think synods may be more important for the lives of Martians than seasons will be, at least for this century. It won't be "what year did you arrive?" It'll be "What synod? Oh really? That's a tough one. Must've been a long trip!"

I think it'll be some mix of synods and Earth years for a while. Eventually Mars years.

I also suspect Martian weeks of 7 days, probably grouped in fours like our months roughly are.
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Offline mark_m

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Re: Mars Timekeeping System
« Reply #74 on: 11/06/2016 07:10 PM »
I just wanted to summarize a little more clearly my posts. This is all-in on a Mars-centric calendar, because I'm suspecting the colonists will have a little too much of an independent streak to base their new calendar off of Earth interactions. It also retains familiar associations of the time of day (in relation to sun position) and months of the year (in relation to seasons). Also, hours, minutes, and seconds are identical or nearly so to the familiar Earth variety.

1 Earth second = 1 second on Mars
59 seconds = 1 Mars minute
60 Mars minutes = 1 Mars hour
25 Mars hours = 1 sol
12 months, January-December, 58 or 59 days each, with the summer solstice occurring around June 40th.

Certainly sols since Jan 1 or seconds since midnight could be used for more technical applications. And of course smartwatches and other devices would have no trouble converting to Earth time. Hmmm, might have to write an Apple Watch app to do that....  ;)

Offline ccdengr

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Re: Mars Timekeeping System
« Reply #75 on: 11/06/2016 07:11 PM »
[Edit: All of that said, it is interesting how easily the mission operators at NASA adopted a Mars clock by changing the length of the second, and hence minute/hour, even though the second is a metric unit, scientifically important.]
If you're talking about the slowed-down wristwatches that were used on MER and MSL, those were useful for easily determining the local time on Mars with regard to sunrise, but nobody was making detailed calculations with the second hand (if they had one, I never saw one.)  SI units are still in effect.

BTW, the use of the word "synod" for an Earth-Mars synodic period is, AFAIK, unique to this forum.  Does anyone know of its use in common aerospace literature?  In all the dictionary definitions I've seen for "synod" it's a religious term, e.g., see https://en.wikipedia.org/wiki/Synod


Offline ThereIWas3

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Re: Mars Timekeeping System
« Reply #76 on: 11/06/2016 07:56 PM »
Remembering that winter starts around Sol 400, etc, is easier to remember than the kind of arbitrary calendars proposed so far.

That is exactly the system used in the Red-Green-Blue Mars books, at least at the start.  They used a term Ls, for Solar Longitude, as described here.  That particular paper used 12 variable-length months, since the seasons are of different lengths on Mars due to the eccentric orbit.  I think in the RGB books they eventually used 24 months, with an additional Mars-specific month interposed between each Earth Month.
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Offline CuddlyRocket

Re: Mars Timekeeping System
« Reply #77 on: 11/06/2016 09:24 PM »
so instead of hours, minutes and seconds, have ores, lepta and defterolepta

Gak. If you're going to change the fundamental units, why copy the base-12/base-60 conventions from Babylonian time?

Because people like them! Or do you think they've survived all these millennia from sheer luck?

Quote
Just use decimal fractions of sols. Half way through the day is 0.5. Each thousandth is nearly 90 seconds, each hundredth is nearly 15 minutes, each tenth almost 2.5hrs, so quick'n'dirty conversion isn't difficult.

A yes, decimal fractions. Which most people never use, preferring rational ones like a half, etc.

I really hope they will use a logical regular calendar, such as the proposed International Fixed Calendar that we OUGHT to use here on Earth...
- Every day of the month falls on the same weekday in each month—the 17th always falls on a Tuesday, for example."

I can't think of anything more horrendous! This is a perfect example of calendar design that exalts logic over humanity. Calendars are meant to be used by people. People who have, for instance, birthdays; and we all know we prefer to celebrate our birthday on some days of the week more than others - those where we don't have to go to work the next day, for instance. Such a fixed calendar means that if you're unlucky enough to be born on a day that's a bad day for a birthday party, it will be a bad day for a birthday party your entire life. The Gregorian calendar rotates the dates through the days of the week giving everyone a shot at good and bad days.

People aren't going to use the 24-hour clock like the military. We could do that now, and often do for train times etc. But we don't.

Who are these people you speak of?

Humanity. Well, most of them.

Quote
I've lived in Germany and traveled to much of Europe, where practically everything runs on 24-hour time, although a 12-hour clock is still more often used in colloquial conversation.

Exactly. Despite 'practically everything' running on 24-hour time, people still prefer to use the 12-hour clock.

Quote
It doesn't seem like adjusting to a 24-hour clock is all that hard given its widespread use, sometimes even in colloquial speech.

No, it's not that hard (although my mother could never get the hang of it!). Makes you wonder why it doesn't seem to prevail over the 12-hour system?

Quote
... it's just that 24-hour time makes a lot of sense.  Obviously it's going to need some adjusting however, since we need to stuff more seconds into each hour.  A Martian Hour would therefore consist 3,698.9675 seconds in 60 Martian Minutes.  Each Martian Minute would consist of 61.649 seconds, while the SI second would be left as is.  This would probably be a good compromise at doing an early Martian timekeeping system.

This is obviously a new usage of the phrase 'good compromise' that I've not previously come across before! Do you really think people are going to use 'minutes' consisting of 61.549 seconds?

People need to remember that a self-sustaining Mars colony is going to be big enough that a substantial fraction of the population won't have careers in any numerate discipline, let alone scientists and engineers (it will probably have the same proportion who are functionally innumerate!). Calendars and time-keeping have to work for everyone, not just scientists and engineers, or even just the well-educated.

Offline Ludus

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Re: Mars Timekeeping System
« Reply #78 on: 11/06/2016 09:35 PM »

So a Synod which is about 780 earth days is about 759.1 Sols.


Synod is not applicable.  Musk intends to use fast transit which negates the need to launch at that specific time.
While true, launches ARE still going to be clustered around the Mars launch window.

I think synods may be more important for the lives of Martians than seasons will be, at least for this century. It won't be "what year did you arrive?" It'll be "What synod? Oh really? That's a tough one. Must've been a long trip!"

I think it'll be some mix of synods and Earth years for a while. Eventually Mars years.

I also suspect Martian weeks of 7 days, probably grouped in fours like our months roughly are.

Everything I've read from Elon suggests he plans around the synodic cycle with a fleet building up and launching in that window regardless of transit times.

Communications latency also waxes and wanes with the synod and I think that will be a major rhythm in the life of Martians.

Offline Lumina

Re: Mars Timekeeping System
« Reply #79 on: 11/06/2016 11:10 PM »
I just wanted to summarize a little more clearly my posts. This is all-in on a Mars-centric calendar, because I'm suspecting the colonists will have a little too much of an independent streak to base their new calendar off of Earth interactions. It also retains familiar associations of the time of day (in relation to sun position) and months of the year (in relation to seasons). Also, hours, minutes, and seconds are identical or nearly so to the familiar Earth variety.

1 Earth second = 1 second on Mars
59 seconds = 1 Mars minute
60 Mars minutes = 1 Mars hour
25 Mars hours = 1 sol
12 months, January-December, 58 or 59 days each, with the summer solstice occurring around June 40th.

Certainly sols since Jan 1 or seconds since midnight could be used for more technical applications. And of course smartwatches and other devices would have no trouble converting to Earth time. Hmmm, might have to write an Apple Watch app to do that....  ;)

Pretty good actually! Workaholics will love the 25 hour sol and procrastinators will be grateful for the 58-59 day months. Something in it for everyone.

As for inconvenience of having to convert between units and so forth, not a problem. Richard Feynman once said that nearly a third of what one has to learn in physics is because historically we've used many different units for what is essentially the same thing. The silver lining is that we will have to use only per second units, so watt-seconds, metres per second etc. instead of kWh, mph and so on. Everyone working off the same per second units will be a positive development actually.

[Edit - a suggestion: since the Mars minute of 59 seconds will cause clocks to drift by about 5 minutes per day relative to solar time, is there a point in sticking to having an integer number of seconds in the Mars minute? Because if you allow decimals and make one Mars Minute equal to 61.6494751 seconds then the Mars Sol of 24 Mars hours of 60 Mars minutes each will be in sync with local solar time. Or you can make it 59.1834961 seconds for 25 hours of 60 Mars minutes and again be in sync...]

[Edit - another one: since on Earth the length of the month varies from 28 to 31 days, you could vary the length of the Martian month a little more so that the seasons at Mars Base Alpha will start in familiar months. You will also need a new rhyme for Martian schoolchildren to learn the arbitrary lengths of month by heart :)]
« Last Edit: 11/06/2016 11:38 PM by Lumina »

Offline mark_m

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Re: Mars Timekeeping System
« Reply #80 on: 11/07/2016 12:12 AM »
[Edit - a suggestion: since the Mars minute of 59 seconds will cause clocks to drift by about 5 minutes per day relative to solar time, is there a point in sticking to having an integer number of seconds in the Mars minute? Because if you allow decimals and make one Mars Minute equal to 61.6494751 seconds then the Mars Sol of 24 Mars hours of 60 Mars minutes each will be in sync with local solar time. Or you can make it 59.1834961 seconds for 25 hours of 60 Mars minutes and again be in sync...]
You're right, I miscalculated, I thought I was a few seconds off per sol, but I'm over 4 1/2 minutes off.  :(

So it's not quite as clean as I'd hoped. Your non-integer number of seconds in a minute would certainly work, and although it seems strange, it might not be bad at all. Most people could just consider it 59 seconds per minute, and devices would know the exact value. Another similar adjustment would be to go back to 60 seconds in a minute, but have an hour be 59 minutes plus an additional 11 seconds at the end of each hour. Then the drift would be really slow, and could be made up for in leap seconds periodically. Or, following your lead, have each hour be 59 minutes plus 11.00976 seconds....
« Last Edit: 11/07/2016 12:17 AM by mark_m »

Offline Lumina

Re: Mars Timekeeping System
« Reply #81 on: 11/07/2016 12:35 AM »
Inspired by Mark_M, here's my complete proposal for Martian timekeeping and calendar:

1 Mars second    =    1               Earth second
1 Mars Minute    =  61.6494751  Earth seconds
1 Mars Hour       =  60               Mars minutes
1 Mars Sol         =  24               Mars hours
1 Mars Year       = 669              Mars sols

January = 50 sols
February = 48 sols (46 sols every 5 Mars years)
March = 54 sols (Spring Equinox: March 36th)
April = 66 sols
May = 67 sols
June = 64 sols (Summer Solstice: June 43rd)
July = 64 sols
August = 63 sols
September = 45 sols (Autumn Equinox: September 30th)
October = 45 sols
November = 44 sols
December = 59 sols (Winter Solstice: December 39th)

Offline Lumina

Re: Mars Timekeeping System
« Reply #82 on: 11/07/2016 12:59 AM »
Just for fun, I was wondering how long it would take to change Mars' solar day length to 24 Earth hours by firing raptors due west from the top of the southern rim of Pavonis Mons (latitude: 1.48 deg N, altitude 14,000 metres), perhaps as part of a terraforming project.

If my math is right, you'd need about 1 million vacuum raptors firing non-stop for 8,600 Mars years.

It will probably be much easier to get used to 1 Mars minute being only approximately 60 seconds!
« Last Edit: 11/07/2016 01:21 AM by Lumina »

Offline ChrisWilson68

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Re: Mars Timekeeping System
« Reply #83 on: 11/07/2016 05:49 AM »
Just for fun, I was wondering how long it would take to change Mars' solar day length to 24 Earth hours by firing raptors due west from the top of the southern rim of Pavonis Mons (latitude: 1.48 deg N, altitude 14,000 metres), perhaps as part of a terraforming project.

If my math is right, you'd need about 1 million vacuum raptors firing non-stop for 8,600 Mars years.

Your calculation is a little off.  It will actually take 1 million vacuum raptors firing approximately infinity Mars years.

The problem is that the exhaust of the raptors stays in the atmosphere and it eventually imparts its momentum back to the planet.

Said another way, unless something is leaving the planet, conservation of angular momentum says the rotational speed won't be affected except by the distribution of mass.  Move more mass to the poles and the rotation will speed up.  But you'd have to move an impractically huge amount of mass to get a 24-hour day.

Offline AncientU

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Re: Mars Timekeeping System
« Reply #84 on: 11/07/2016 10:39 AM »
What is interesting about a 24 hour day?
(Earth's random and continually changing rotation rate aside, that is...)

Note: When we start terraforming, polar ices will be more evenly distributed and rotation rate will actually get slower -- longer days, not shorter.
« Last Edit: 11/07/2016 10:43 AM by AncientU »
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Offline Lumina

Re: Mars Timekeeping System
« Reply #85 on: 11/07/2016 11:20 AM »
Just for fun, I was wondering how long it would take to change Mars' solar day length to 24 Earth hours by firing raptors due west from the top of the southern rim of Pavonis Mons (latitude: 1.48 deg N, altitude 14,000 metres), perhaps as part of a terraforming project.

If my math is right, you'd need about 1 million vacuum raptors firing non-stop for 8,600 Mars years.

Your calculation is a little off.  It will actually take 1 million vacuum raptors firing approximately infinity Mars years.

The problem is that the exhaust of the raptors stays in the atmosphere and it eventually imparts its momentum back to the planet.

Said another way, unless something is leaving the planet, conservation of angular momentum says the rotational speed won't be affected except by the distribution of mass.  Move more mass to the poles and the rotation will speed up.  But you'd have to move an impractically huge amount of mass to get a 24-hour day.

I think you are right that this fun idea is theoretically as well as practically infeasible. I didn't geek out all the way with the math of atmospheric pressure at that altitude, the resulting momentum exchange with the plume, the exhaust velocity relative to the escape velocity of a particle launched westwards from 14,000m / 28,000m up on Mars, the angle of the plume to the horizontal and whether all that's enough to get a plume to punch through the 30 pascals of pressure at Olympus Mons and to escape into space (I changed to Pavonis at the last minute for its equatorial location). Even if I did go through all that, you're probably right about the infinity thing, but never let the math stand in the way of a good laugh!
« Last Edit: 11/07/2016 11:24 AM by Lumina »

Offline Paul451

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Re: Mars Timekeeping System
« Reply #86 on: 11/07/2016 11:35 AM »
Inspired by Mark_M, here's my complete proposal for Martian timekeeping and calendar:
1 Mars second    =    1               Earth second
1 Mars Minute    =  61.6494751  Earth seconds
1 Mars Hour       =  60               Mars minutes
1 Mars Sol         =  24               Mars hours
1 Mars Year       = 669              Mars sols
January = 50 sols
February = 48 sols (46 sols every 5 Mars years)
March = 54 sols (Spring Equinox: March 36th)
April = 66 sols
May = 67 sols
June = 64 sols (Summer Solstice: June 43rd)
July = 64 sols
August = 63 sols
September = 45 sols (Autumn Equinox: September 30th)
October = 45 sols
November = 44 sols
December = 59 sols (Winter Solstice: December 39th)

Do you really not see how incredibly annoying that would be to actually live with? Fractional seconds per minute? "Months" ranging from 44 to 67 days in a random pattern? Why? What possible advantage could there be to having such a system?

Offline mark_m

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Re: Mars Timekeeping System
« Reply #87 on: 11/07/2016 01:12 PM »
Do you really not see how incredibly annoying that would be to actually live with? Fractional seconds per minute? "Months" ranging from 44 to 67 days in a random pattern? Why? What possible advantage could there be to having such a system?
Unfortunately 88,775 (the integer number of seconds in a sol) doesn't divide up nicely, so if you're keeping seconds as they are and want time periods at all roughly analogous to minutes and hours, it seems like you have 3 choices: a few "leap" seconds per hour,  almost 5 "leap" minutes per day, or Lumina's suggestion of non-integer seconds per minute (which conveniently also takes care of the fractional number of seconds in a sol). With digital devices keeping and calculating time, which is really the least intrusive?

I'm assuming the variable length months is related to orbital mechanics and Martian seasons. I could see 56 day months except for February, which would be 52 or 53 days. The equinoxes and solstices might shift a bit, but I think they'd be close enough to feel comfortable.

Offline Oersted

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Re: Mars Timekeeping System
« Reply #88 on: 11/07/2016 06:03 PM »
I really hope they will use a logical regular calendar, such as the proposed International Fixed Calendar that we OUGHT to use here on Earth...
- Every day of the month falls on the same weekday in each month—the 17th always falls on a Tuesday, for example."

I can't think of anything more horrendous! This is a perfect example of calendar design that exalts logic over humanity. Calendars are meant to be used by people. People who have, for instance, birthdays; and we all know we prefer to celebrate our birthday on some days of the week more than others - those where we don't have to go to work the next day, for instance. Such a fixed calendar means that if you're unlucky enough to be born on a day that's a bad day for a birthday party, it will be a bad day for a birthday party your entire life. The Gregorian calendar rotates the dates through the days of the week giving everyone a shot at good and bad days.

If that is the worst you can come up with about the International Fixed Calendar then I am tempted to take that as a ringing endorsement of the idea! Most people happily celebrate their birthday on the nearest practical weekend day or holiday. Or are you saying they only celebrate in the years where their birthdays happen to fall on a weekend? :-)

No worries, we can agree to disagree. What we think is not important anyway.
« Last Edit: 11/07/2016 06:03 PM by Oersted »

Offline ChrisWilson68

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Re: Mars Timekeeping System
« Reply #89 on: 11/07/2016 06:08 PM »
I really hope they will use a logical regular calendar, such as the proposed International Fixed Calendar that we OUGHT to use here on Earth...
- Every day of the month falls on the same weekday in each month—the 17th always falls on a Tuesday, for example."

I can't think of anything more horrendous! This is a perfect example of calendar design that exalts logic over humanity. Calendars are meant to be used by people. People who have, for instance, birthdays; and we all know we prefer to celebrate our birthday on some days of the week more than others - those where we don't have to go to work the next day, for instance. Such a fixed calendar means that if you're unlucky enough to be born on a day that's a bad day for a birthday party, it will be a bad day for a birthday party your entire life. The Gregorian calendar rotates the dates through the days of the week giving everyone a shot at good and bad days.

If that is the worst you can come up with about the International Fixed Calendar then I am tempted to take that as a ringing endorsement of the idea!

He didn't say that's the worst, just an example.

The International Fixed Calendar just trades some disadvantages of the Gregorian calendar for other disadvantages.  Which disadvantages are preferable is purely subjective.  I hope you can recognize that just because someone prefers the Gregorian calendar doesn't mean they're stupid or don't understand the IFC.  They just have different things they value.

Offline Robotbeat

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Re: Mars Timekeeping System
« Reply #90 on: 11/07/2016 06:23 PM »
Leave seconds, minutes, and hours alone, you insane people!  ;D
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Offline Hyperion5

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Re: Mars Timekeeping System
« Reply #91 on: 11/08/2016 01:42 AM »
Quote
... it's just that 24-hour time makes a lot of sense.  Obviously it's going to need some adjusting however, since we need to stuff more seconds into each hour.  A Martian Hour would therefore consist 3,698.9675 seconds in 60 Martian Minutes.  Each Martian Minute would consist of 61.649 seconds, while the SI second would be left as is.  This would probably be a good compromise at doing an early Martian timekeeping system.

This is obviously a new usage of the phrase 'good compromise' that I've not previously come across before! Do you really think people are going to use 'minutes' consisting of 61.549 seconds?

People need to remember that a self-sustaining Mars colony is going to be big enough that a substantial fraction of the population won't have careers in any numerate discipline, let alone scientists and engineers (it will probably have the same proportion who are functionally innumerate!). Calendars and time-keeping have to work for everyone, not just scientists and engineers, or even just the well-educated.

Leave seconds, minutes, and hours alone, you insane people!  ;D

No need for exclamation marks or questioning of sanity, gentlemen.   8)  I think all of us realize that a substantial fraction of any population, be they in South Korea or South Africa, won't be very numerate.  That's not what the issue is about.  All of this boils down to how do you create proper Martian time zones using Earth-based measures of time?  Most of us have agreed that we should keep the SI second.  The problem is unless you then adjust the Martian Minute or Martian Hour, you wind up with the 39-minute long "Zero Hour", which ruins any attempt to create proper time zones.  Unless you can miraculously force Mars to have the same length day as Earth, this issue isn't going away.  The alternative is not to have any time zones at all, which I think is wildly unfeasible, but that's exactly what it appears you are proposing. 

Offline Lumina

Re: Mars Timekeeping System
« Reply #92 on: 11/08/2016 10:27 AM »
Leave seconds, minutes, and hours alone, you insane people!  ;D

"No one pretends that democracy is perfect or all-wise. Indeed, it has been said that democracy is the worst form of Government except all those other forms that have been tried from time to time."

This is from a speech Winston Churchill gave to the House of Commons, November 11, 1947.

After weighing the alternatives, and considering that all timekeeping is basically digital nowadays, I suggest that having a fractional number of seconds per Martian minute is the worst form of timekeeping except all those other forms that have been suggested from time to time :)
« Last Edit: 11/08/2016 10:28 AM by Lumina »

Offline Lumina

Re: Mars Timekeeping System
« Reply #93 on: 11/08/2016 10:49 AM »
Inspired by Mark_M, here's my complete proposal for Martian timekeeping and calendar:
1 Mars second    =    1               Earth second
1 Mars Minute    =  61.6494751  Earth seconds
1 Mars Hour       =  60               Mars minutes
1 Mars Sol         =  24               Mars hours
1 Mars Year       = 669              Mars sols
January = 50 sols
February = 48 sols (46 sols every 5 Mars years)
March = 54 sols (Spring Equinox: March 36th)
April = 66 sols
May = 67 sols
June = 64 sols (Summer Solstice: June 43rd)
July = 64 sols
August = 63 sols
September = 45 sols (Autumn Equinox: September 30th)
October = 45 sols
November = 44 sols
December = 59 sols (Winter Solstice: December 39th)

Do you really not see how incredibly annoying that would be to actually live with? Fractional seconds per minute? "Months" ranging from 44 to 67 days in a random pattern? Why? What possible advantage could there be to having such a system?

The lengh of the months is not random at all and it certainly isn't any more arbitrary than the length of months on Earth (see the children's rhyme below).

The intent of the concept is to keep the most important features of our calendar as close to being intact and familiar as possible while adapting to the orbital realities of Mars by making the fewest possible adjustments in the least worst places.

One important feature of a Mars calendar in my opinion is to have the familiar names of the months aligned with the familiar orbital seasons. I tried to do that by aiming to get all the solstices and equinoxes to occur two thirds of the way through their usual months. This then constrained somewhat the choices of how many days I could give to each month, and that was the source of the variance in month lengths. It's a loose constraint because you can take days from April and give them to May for instance without affecting the solstice/equinox dates, so there are many other ways to do this if you don't like the result. I do admit to putting my finger on the scales and giving extra days to December so that you can have a long one to two week end of year holiday without butchering the number of work days in that month.

"Thirty days hath September,
April, June, and November.
All the rest have thirty-one,
Except for February alone,
Which hath but twenty-eight days clear,
And twenty-nine in each leap year."
« Last Edit: 11/08/2016 10:56 AM by Lumina »

Offline baldusi

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Re: Mars Timekeeping System
« Reply #94 on: 11/08/2016 03:38 PM »
Leave seconds, minutes, and hours alone, you insane people!  ;D

"No one pretends that democracy is perfect or all-wise. Indeed, it has been said that democracy is the worst form of Government except all those other forms that have been tried from time to time."

This is from a speech Winston Churchill gave to the House of Commons, November 11, 1947.

After weighing the alternatives, and considering that all timekeeping is basically digital nowadays, I suggest that having a fractional number of seconds per Martian minute is the worst form of timekeeping except all those other forms that have been suggested from time to time :)

I insist: 25 martian hour with 53 martian minutes of 67 seconds. leaves an error of .5 seconds/sol. Don't call them hour and minutes, put another name, and you are done.

Offline ThereIWas3

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Re: Mars Timekeeping System
« Reply #95 on: 11/08/2016 04:02 PM »
At a different level, what to choose as the origin for figuring years on Mars?  Many SF books take the "year of first manned landing" as the origin, and figure in Mars Years before and after that.  In Heinlein's "Podkayne of Mars" the heroine, who was born on Mars, describes herself as being a bit over 8 years old, or 15 in Earth Years.

Earth cultures have handled varying traditional calendars without much problem.  Ask someone in Japan what year it is and they are just as likely to answer "Heisei 28" as they are "2016".  You will even find dates written that way on public announcements.
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Offline Duds

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Re: Mars Timekeeping System
« Reply #96 on: 11/08/2016 05:26 PM »
Those living on Mars would want a sunlight oriented system for sols like we have on Earth.  I think it's a bad idea to alter the second proportionately as some elsewhere have suggested.  Although not noticed by Mars residents it could complicate engineering calculations and be a source of error.

My radical Mars quirky solution is to use normal Earth hours minutes and seconds but at midnight when all but the night shift and those wild & crazy late night Mars party animals are asleep, have the clocks go to Red Time where the extra 39 minutes 35.244 seconds are added and counted down before resuming at say 12:01.  Mars sols are preserved.  Everyone in the inner solar system is using standard seconds, etc.  And a party time is enshrined in unique Mars culture.

Similar to Stanley Robinsons sci-fi Red Mars trilogy idea for martian time keeping

Online guckyfan

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Re: Mars Timekeeping System
« Reply #97 on: 11/08/2016 05:42 PM »

My radical Mars quirky solution is to use normal Earth hours minutes and seconds but at midnight when all but the night shift and those wild & crazy late night Mars party animals are asleep, have the clocks go to Red Time where the extra 39 minutes 35.244 seconds are added and counted down before resuming at say 12:01.  Mars sols are preserved.  Everyone in the inner solar system is using standard seconds, etc.  And a party time is enshrined in unique Mars culture.

The perfect solution as long as there is just one major settlement. When people are spread all over Mars and people live in all time zones, there is a problem.

You can keep that part hour locally everywhere at midnight, that would make for odd jumps of time between time zones.

You can move that part hour around locally, so that it is everywhere at the same time, but that would have it during the day in many locations. Despite the disadvantage I like this option best.

Offline Paul451

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Re: Mars Timekeeping System
« Reply #98 on: 11/08/2016 06:40 PM »
The lengh of the months is not random at all and it certainly isn't any more arbitrary than the length of months on Earth

It really is.

Even Earth's arbitrary and centuries abused calendar is just:

31, 28*, 31, 30, 31, 30, 31,
31, 30, 31, 30, 31.

A fairly clear 31/30, 31/30 pattern, with just one odd month which is then the home of that single leap day (nicely signposted by its odd-man status). Though it would have better if the damn Romans hadn't messed with August... 31, 29/30, 31, 30, 31, 30, 31, 30, 31, 30, 31, 30. Even better if they'd kept the March start, 31, 30, 31, 30, 31, 30, 31, 30, 31, 30, 31, 29/30, so the odd-man is at the end.

(Thanks to this relative uniformity, the solstices and equinoxes are always somewhere around the 20th.)

For Mars, you've got a "pattern" of....

50, 48/46, 54, 66, 67, 64, 64, 63, 45, 45, 44, 59. (I actually ran out of colours that display well.)

(With equinoxes/solstices varying: 36, 43, 30, 39. And those dates will each vary by three days, drifting back and forth as they interact with the leap-year cycle, just as Earth's do.)

(see the children's rhyme below).
...
Thirty days hath September, April, June, and November.
All the rest have thirty-one,
Except for February ...

Yeah, just two repeated values, 30 & 31, and one thrown exception - and we consider it complex and arbitrary! Which is why so many nerdlings are attracted to the 13-month universal calender.

Now make up a rhyme for your system.

The intent of the concept is to keep the most important features of our calendar as close to being intact and familiar as possible

What's familiar except "twelve sort-of-months"?

One important feature of a Mars calendar in my opinion is to have the familiar names of the months

Which only serves to force people to specify which calendar they are talking about. Like having to specify which regional "foot" you are using in the various pre-metric systems, or ounce, or pound, or mile...

January or Mars-January?

This then constrained somewhat the choices of how many days I could give to each month, [etc etc]

So why not give up the whole thing? It doesn't work. It can't work. The Martian year is too different from the Earth year.

Just count Sols. They are going to do that anyway. And they would have to in order to understand your system, certainly no-one is going to remember it.

(And if you must insist on some kind of calendar, at least use a simple one like the Darian 7/4/24 variants.)

[edit: Plurals vs possessives.]
« Last Edit: 11/08/2016 07:27 PM by Paul451 »

Offline Paul451

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Re: Mars Timekeeping System
« Reply #99 on: 11/08/2016 07:12 PM »
At a different level, what to choose as the origin for figuring years on Mars?  Many SF books take the "year of first manned landing" as the origin, and figure in Mars Years before and after that.

You mean the same way it's currently Year 524 in the American Calendar?

[edit: Or 71 AE, if we're using the SF books I read as a kid. Still waiting for us to switch to the more sensible "Atomic Era" calendar.]

When people are spread all over Mars and people live in all time zones, there is a problem.
You can keep that part hour locally everywhere at midnight, that would make for odd jumps of time between time zones.

Sounds like the problem is in having time-zones. Universal Mars Time, FTW.

I insist: 25 martian hour with 53 martian minutes of 67 seconds. leaves an error of .5 seconds/sol. Don't call them hour and minutes, put another name, and you are done.

While I insist: if you aren't going to use hours and minutes, don't use pretend hours & minutes. Especially don't use weird numbering like 25/53/67. (At least it's integers, but still, two primes?)
« Last Edit: 11/08/2016 07:26 PM by Paul451 »

Offline MP99

Re: Mars Timekeeping System
« Reply #100 on: 11/08/2016 07:17 PM »
Leave seconds, minutes, and hours alone, you insane people!  ;D
Make a sol into 24h and 40m, then have a short day of 24h 30m whenever you get 10 mins ahead - about every 25th day.

Cheers, Martin

Offline Lumina

Re: Mars Timekeeping System
« Reply #101 on: 11/08/2016 07:48 PM »
No, Paul451, the month lengths which I calculated using a linear optimization rig in Excel to satisfy five equations are not at all random, because the main point of having months is to remind us of the season and unlike Earth, on Mars the seasons have variable lengths (see the drawing).

So in my concept the months are Earth-like in their number, names and association with seasons, solstices and equinoxes. The price paid is the months having a variable length, which is the least sacrifice in my subjective opinion. (You are welcome to your own subjective opinion, to which I will not agree). This is a concept suitable for Martians who prize and value symbolic reminders of their Earth roots in their daily lives.

If you insist that months must have the same lengths, there are many options, you could simply create a new calendar with 22 months of 30 days plus a New Year's holiday period of 9 days, and give the months (and the holiday period) new names. Or 19 months, 15 with 35 days and 4 with 36. Or dozens of other possibilities. In any of those, a new set of months would be associated with the orbital seasons, and some seasons would have more months. This is a concept more suitable for Martians who want to subtly emphasize their independence from Earth, and in the long term it might be "better" functionally speaking, once the Martians learn how to use it.
« Last Edit: 11/08/2016 07:54 PM by Lumina »

Offline baldusi

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Re: Mars Timekeeping System
« Reply #102 on: 11/08/2016 08:25 PM »
I insist: 25 martian hour with 53 martian minutes of 67 seconds. leaves an error of .5 seconds/sol. Don't call them hour and minutes, put another name, and you are done.

While I insist: if you aren't going to use hours and minutes, don't use pretend hours & minutes. Especially don't use weird numbering like 25/53/67. (At least it's integers, but still, two primes?)
Those are the divisors of the Martian average sol. It is surprisingly difficult to keep "nice" divisors and the average sol length in seconds. Leap minutes would help a lot, thou.
As I explained before, the Mars synodic day has a much greater variance than Earth, so that's where the answer might lie. Does anyone has a Mars synodic day calculator for the whole year?

Offline Paul451

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Re: Mars Timekeeping System
« Reply #103 on: 11/08/2016 11:11 PM »
Leave seconds, minutes, and hours alone, you insane people!
Make a sol into 24h and 40m, then have a short day of 24h 30m whenever you get 10 mins ahead - about every 25th day.

If you're going to have leap-hours, why not alternate between 24 and 25hr sols? That way you can at least use whole hours, as well as whole minutes.

A pattern of 24/25/25 gets you within 24sec/sol. But that obviously lends itself to a 6 day week. How much do we hate Mondays?

If you want to keep the 7 day week, the 24/25 pattern has to be more complex, which gets back to the problem of trying to sync Martian day-length with SI seconds; it always creates a system that's human-hostile.

But for the sake of the exercise: if you have 24/24/25/25/25/25/25 hr weeks, then every fifth or sixth week, you need to remove one hour from one of the 25hr sols.

I've also mentioned before that if you drop a named weekday (ie, have a 6 day week) 3 times every 16 weeks, you can keep the day of the week within 12hrs of Earth's UTC, ie, the Mars day-of-the-week will be no further out than anywhere on Earth.

So one of the patterns needs to lose an hour, alternating between every fifth or sixth week, and the other pattern needs to skip an entire sol every fourth or fifth week. There might be an elegant way of syncing the two up if the second pattern alternates between skipping a 24hr or 25hr sol, giving you whole hours and weekdays that stay synced to the day-of-the-week on Earth, but my brain doesn't want to see the pattern.

--

If you insist that months must have the same lengths,

On the contrary, I object to the whole idea of using months on Mars.

...I just object to yours more than most.

there are many options

And they're all horrible. (One of the Darian variants is probably the best of a bad bunch.)

because the main point of having months is to remind us of the season and unlike Earth, on Mars the seasons have variable lengths (see the drawing).

You're confusing the astronomical seasons with the practical Earthly reasons why humans track seasons, changes to the local environment. Thinking of four uniform seasons on Earth is a very temperate-climate (US/Euro) chauvinism.

North of where I live, there are about five main "seasons", the short monsoon season, two short seasons either side (storm and flood, respectively), and two long seasons making up the bulk of the year. So there's the long dry season, leading to a short stormy season with highly variable weather, leading to the very short actual monsoon rain season, followed by the calm but very wet period where the land is flooded, followed by a long green season as the waters move through different lands, back to the long dry. (Although pre-contact natives apparently used multiple calendars simultaneously, different cycles for major food groups and weather risks. Nomadic tribes would have different calendars for different regions/years on their long-cycle.) I imagine at high latitudes, especially above the polar circle, there are similar varying length "seasons" based around long winters and short summers.

Likewise, for practical purposes, Mars has two seasons. Dust storm season and not dust storm season. That's more like monsoon regions on Earth, but dust-storm season runs closer to half the year. So again, just counting Sols is sufficient to keep track of the things which will actually matter to colonists.

(It's not like they're going to be planting crops or tracking lambing season based around the Martian equinoxes. "Spring's comin', Samael, best be tending your flock.")

[edit: Typos and stupid]
« Last Edit: 11/08/2016 11:20 PM by Paul451 »

Online guckyfan

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Re: Mars Timekeeping System
« Reply #104 on: 11/09/2016 05:49 AM »
If you're going to have leap-hours, why not alternate between 24 and 25hr sols? That way you can at least use whole hours, as well as whole minutes.

People won't adjust to different day length. The 1 hour switch twice a year for daylight saving is bad enough. Many, like me, want to get rid of it.

I agree about the part where local seasons don't affect people a lot in equatorial regions on Mars. So the length of the calender year does not need to be aligned with the actual martian year. Either just keep the length of the earth year, with a few less days to adjust for the longer days or divide the martian year by 2 and make it 2 calendar years.

On earth the moon year is also widely adhered to and it shifts the seasons around the year.

Offline Lumina

Re: Mars Timekeeping System
« Reply #105 on: 11/09/2016 10:18 AM »
Paul451, just counting Sols (which we already do) without engaging the tougher problems is a copout, and your proposal to alternate 24h with 25h days is a nonstarter given that sunrise would move several minutes each day. Dropping hours or days in order to re-sync creates much bigger problems than the self-inflicted problem it addresses.

Do you have any serious proposals for subdividing the length of a Sol and the length of the Martian year into smaller units?

As for the seasons not mattering on Mars because we won't have goats there or whatever: there is a large temperature swing between seasons and it has been correlated with changing surface features such as recurring slope lineae (RSL). We should not presume that Martians won't care about the seasonally-varying surface temperatures, especially over the very long term as Mars is being terraformed. Calendars are products with a lifespan of thousands of years designed by humans, and it is the duty of the designer human to make the product work 10, 100 and 1000 years out.
« Last Edit: 11/09/2016 10:28 AM by Lumina »

Online guckyfan

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Re: Mars Timekeeping System
« Reply #106 on: 11/09/2016 11:42 AM »
It seems a good smoothly divided day can be made only when giving up the length of the earth second. By making it slightly longer you can keep the division 60/60/24 for a sol.

That done they can use the martian year and give it 24 months. Or keep 12 month but months of over 50 days seem unwieldy to me.

Offline envy887

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Re: Mars Timekeeping System
« Reply #107 on: 11/09/2016 12:54 PM »
It seems a good smoothly divided day can be made only when giving up the length of the earth second. By making it slightly longer you can keep the division 60/60/24 for a sol.

That done they can use the martian year and give it 24 months. Or keep 12 month but months of over 50 days seem unwieldy to me.

There are many things that are measured accurately enough in seconds for this to make a significant difference, unlike making each minute or hour a little longer (e.g. 61.xx/60/24 or 60/61.xx/24).

Online guckyfan

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Re: Mars Timekeeping System
« Reply #108 on: 11/09/2016 01:51 PM »

There are many things that are measured accurately enough in seconds for this to make a significant difference, unlike making each minute or hour a little longer (e.g. 61.xx/60/24 or 60/61.xx/24).

That is not relevant IMO. Time can be precisely measured, independent of the arbitrary definition of a second. Maybe call it differently to avoid confusion. But I doubt that is necessary as use of that metric would be universal on Mars except for scientific purposes.

Offline philw1776

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Re: Mars Timekeeping System
« Reply #109 on: 11/09/2016 02:54 PM »

My radical Mars quirky solution is to use normal Earth hours minutes and seconds but at midnight when all but the night shift and those wild & crazy late night Mars party animals are asleep, have the clocks go to Red Time where the extra 39 minutes 35.244 seconds are added and counted down before resuming at say 12:01.  Mars sols are preserved.  Everyone in the inner solar system is using standard seconds, etc.  And a party time is enshrined in unique Mars culture.

The perfect solution as long as there is just one major settlement. When people are spread all over Mars and people live in all time zones, there is a problem.

You can keep that part hour locally everywhere at midnight, that would make for odd jumps of time between time zones.

You can move that part hour around locally, so that it is everywhere at the same time, but that would have it during the day in many locations. Despite the disadvantage I like this option best.

People in sun centered different time zones may have major technical advances like smart phones/watches :) that allow for the infrequent Red Time anomalies between zones.
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Offline mark_m

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Re: Mars Timekeeping System
« Reply #110 on: 11/09/2016 03:34 PM »

There are many things that are measured accurately enough in seconds for this to make a significant difference, unlike making each minute or hour a little longer (e.g. 61.xx/60/24 or 60/61.xx/24).

That is not relevant IMO. Time can be precisely measured, independent of the arbitrary definition of a second. Maybe call it differently to avoid confusion. But I doubt that is necessary as use of that metric would be universal on Mars except for scientific purposes.

Having a marssecond slightly longer than an SI second would make everything divide up evenly, and, again, any timekeeping device could easily show and convert between Earth UTC and local time. However, the SI second is a component of so many units, the crossover from scientific to common use isn't a clearly defined boundary. I do like the clean break to a Mars-centric system, but still think the price is too high, in terms of confusion opportunities and inconveniences.

What's the real negative of having seconds and minutes match their existing definitions, but hours are defined as 1/24th of a sol (61.xxx minutes)? It's just one number or the other, and it's close enough to still "feel" like an hour in common usage. I'm having trouble imagining a situation where this would even be an inconvenience. People doing mental math maybe?

People in sun centered different time zones may have major technical advances like smart phones/watches :) that allow for the infrequent Red Time anomalies between zones.
The only advantage of the Red Time system is that the Mars hour still matches the Earth hour? I don't think that's worth the constantly changing offsets between timezones. Sure, a device could always tell you the time for any timezone, but I don't see that what you gain is worth the hassle.

[edit: grammar]
« Last Edit: 11/09/2016 03:35 PM by mark_m »

Online guckyfan

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Re: Mars Timekeeping System
« Reply #111 on: 11/09/2016 03:44 PM »
Having a marssecond slightly longer than an SI second would make everything divide up evenly, and, again, any timekeeping device could easily show and convert between Earth UTC and local time. However, the SI second is a component of so many units, the crossover from scientific to common use isn't a clearly defined boundary. I do like the clean break to a Mars-centric system, but still think the price is too high, in terms of confusion opportunities and inconveniences.

What's the real negative of having seconds and minutes match their existing definitions, but hours are defined as 1/24th of a sol (61.xxx minutes)? It's just one number or the other, and it's close enough to still "feel" like an hour in common usage. I'm having trouble imagining a situation where this would even be an inconvenience. People doing mental math maybe?

I agree that keeping the second has major advantages. But fractional minutes to the hour? Hard to imagine, even if timepieces can handle it. It goes against the grain of peoples minds.

Offline envy887

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Re: Mars Timekeeping System
« Reply #112 on: 11/09/2016 03:54 PM »
Having a marssecond slightly longer than an SI second would make everything divide up evenly, and, again, any timekeeping device could easily show and convert between Earth UTC and local time. However, the SI second is a component of so many units, the crossover from scientific to common use isn't a clearly defined boundary. I do like the clean break to a Mars-centric system, but still think the price is too high, in terms of confusion opportunities and inconveniences.

What's the real negative of having seconds and minutes match their existing definitions, but hours are defined as 1/24th of a sol (61.xxx minutes)? It's just one number or the other, and it's close enough to still "feel" like an hour in common usage. I'm having trouble imagining a situation where this would even be an inconvenience. People doing mental math maybe?

I agree that keeping the second has major advantages. But fractional minutes to the hour? Hard to imagine, even if timepieces can handle it. It goes against the grain of peoples minds.

Why? What do you measure with the hour that will be significantly different if it's 61 and change vs. 60 minutes?

Online launchwatcher

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Re: Mars Timekeeping System
« Reply #113 on: 11/09/2016 05:11 PM »
Having a marssecond slightly longer than an SI second would make everything divide up evenly, and, again, any timekeeping device could easily show and convert between Earth UTC and local time. However, the SI second is a component of so many units, the crossover from scientific to common use isn't a clearly defined boundary. I do like the clean break to a Mars-centric system, but still think the price is too high, in terms of confusion opportunities and inconveniences.

What's the real negative of having seconds and minutes match their existing definitions, but hours are defined as 1/24th of a sol (61.xxx minutes)? It's just one number or the other, and it's close enough to still "feel" like an hour in common usage. I'm having trouble imagining a situation where this would even be an inconvenience. People doing mental math maybe?

I agree that keeping the second has major advantages. But fractional minutes to the hour? Hard to imagine, even if timepieces can handle it. It goes against the grain of peoples minds.
You may not have noticed but there are fractional minutes every so often in terrestrial timekeeping.  Leap seconds (periodically declared by the International Earth Rotation Service) involve a 61-second minute.   Most people don't notice, but computers do. 

There are a number of ways of coping with it in computer timekeeping.   One approach is the leap smear -- lengthen each second by a few milliseconds until enough extra time is inserted to bring the clock back in sync with the post-leap-second UTC.
 

Offline Oersted

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Re: Mars Timekeeping System
« Reply #114 on: 11/09/2016 08:02 PM »
I really hope they will use a logical regular calendar, such as the proposed International Fixed Calendar that we OUGHT to use here on Earth...
- Every day of the month falls on the same weekday in each month—the 17th always falls on a Tuesday, for example."

I can't think of anything more horrendous! This is a perfect example of calendar design that exalts logic over humanity. Calendars are meant to be used by people. People who have, for instance, birthdays; and we all know we prefer to celebrate our birthday on some days of the week more than others - those where we don't have to go to work the next day, for instance. Such a fixed calendar means that if you're unlucky enough to be born on a day that's a bad day for a birthday party, it will be a bad day for a birthday party your entire life. The Gregorian calendar rotates the dates through the days of the week giving everyone a shot at good and bad days.

If that is the worst you can come up with about the International Fixed Calendar then I am tempted to take that as a ringing endorsement of the idea!

He didn't say that's the worst, just an example.

The International Fixed Calendar just trades some disadvantages of the Gregorian calendar for other disadvantages.  Which disadvantages are preferable is purely subjective.  I hope you can recognize that just because someone prefers the Gregorian calendar doesn't mean they're stupid or don't understand the IFC.  They just have different things they value.


I really think you need to go back and read my posting. At no point did I belittle Cuddlyrocket or insinuate that he was stupid. Your posting raises the temperature in a way that is unwarranted.

Here is my full posting:

If that is the worst you can come up with about the International Fixed Calendar then I am tempted to take that as a ringing endorsement of the idea! Most people happily celebrate their birthday on the nearest practical weekend day or holiday. Or are you saying they only celebrate in the years where their birthdays happen to fall on a weekend? :-)

No worries, we can agree to disagree. What we think is not important anyway.
« Last Edit: 11/09/2016 08:02 PM by Oersted »

Online guckyfan

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Re: Mars Timekeeping System
« Reply #115 on: 11/09/2016 08:26 PM »

I agree that keeping the second has major advantages. But fractional minutes to the hour? Hard to imagine, even if timepieces can handle it. It goes against the grain of peoples minds.

Why? What do you measure with the hour that will be significantly different if it's 61 and change vs. 60 minutes?

Humans will live by that time. Many would not feel comfortable with it. 60 as a number that is dividable by many numbers was chosen for a reason.

Offline Robotbeat

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Re: Mars Timekeeping System
« Reply #116 on: 11/09/2016 09:01 PM »
Keep hours, minutes, seconds the same. They're nice integers that are divisible by every integer up to & including 6. The only thing that needs to change is the day, which we already do with sols. Just have 39 extra minutes. Pretty simple and reduces confusion. Time zones are dumb anyway, especially since Mars population will probably be concentrated in one city for a while.

Kim Stanley Robinson has a discussion of this.

And this should go in the Mars section.
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Offline Lumina

Re: Mars Timekeeping System
« Reply #117 on: 11/09/2016 11:19 PM »

I agree that keeping the second has major advantages. But fractional minutes to the hour? Hard to imagine, even if timepieces can handle it. It goes against the grain of peoples minds.

Why? What do you measure with the hour that will be significantly different if it's 61 and change vs. 60 minutes?

Humans will live by that time. Many would not feel comfortable with it. 60 as a number that is dividable by many numbers was chosen for a reason.

guckyfan, that's why I felt it was best to keep the Mars hour at an integer number of Mars minutes (60) and to change instead the Mars minute to a fractional number of seconds (61.xx). We do mental math and other things with parts of hours, but not so much with parts of minutes.

Offline ChrisWilson68

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Re: Mars Timekeeping System
« Reply #118 on: 11/09/2016 11:48 PM »
I really hope they will use a logical regular calendar, such as the proposed International Fixed Calendar that we OUGHT to use here on Earth...
- Every day of the month falls on the same weekday in each month—the 17th always falls on a Tuesday, for example."

I can't think of anything more horrendous! This is a perfect example of calendar design that exalts logic over humanity. Calendars are meant to be used by people. People who have, for instance, birthdays; and we all know we prefer to celebrate our birthday on some days of the week more than others - those where we don't have to go to work the next day, for instance. Such a fixed calendar means that if you're unlucky enough to be born on a day that's a bad day for a birthday party, it will be a bad day for a birthday party your entire life. The Gregorian calendar rotates the dates through the days of the week giving everyone a shot at good and bad days.

If that is the worst you can come up with about the International Fixed Calendar then I am tempted to take that as a ringing endorsement of the idea!

He didn't say that's the worst, just an example.

The International Fixed Calendar just trades some disadvantages of the Gregorian calendar for other disadvantages.  Which disadvantages are preferable is purely subjective.  I hope you can recognize that just because someone prefers the Gregorian calendar doesn't mean they're stupid or don't understand the IFC.  They just have different things they value.


I really think you need to go back and read my posting. At no point did I belittle Cuddlyrocket or insinuate that he was stupid. Your posting raises the temperature in a way that is unwarranted.

The second part of my post was in reference to your earlier post, quoted above: "I really hope they will use a logical regular calendar, such as the proposed International Fixed Calendar that we OUGHT to use here on Earth".

When you say you hope they will use a "logical" calendar like the IFC on Earth, you're implying that the alternative, the Gregorian calendar we do use is not logical.  I was trying to get you away from the idea that your particular preferences on calendars are really objectively better, and instead substitute the idea that people who disagree do so for subjective reasons.

I did not claim you said anyone was stupid.  I said I hoped that you could recognize the people who disagree with you are not.  It was an invitation for you to agree with that statement that you don't think people who disagree are stupid.

Offline Lumina

Re: Mars Timekeeping System
« Reply #119 on: 11/10/2016 04:11 AM »
Inspired by Mark_M, here's my complete proposal for Martian timekeeping and calendar:

1 Mars second    =    1               Earth second
1 Mars Minute    =  61.6494751  Earth seconds
1 Mars Hour       =  60               Mars minutes
1 Mars Sol         =  24               Mars hours
1 Mars Year       = 669              Mars sols

(snip)


This is a Martian calendar with 23 months plus an end of year holiday-only month. This concept is suitable for a civilization that would like to stamp its calendar with its own identity, distinct from the Earth identity. It also helps to instantly recognize Mars dates in texts which also include Earth dates. Month lengths are either 28 or 30 days.

Winter - 2   (28 sols)
Winter - 3   (28)
Winter - 4   (28)
Winter - 5   (28)
Spring-E   (28) Spring Equinox on the 22nd
Spring-2   (28)
Spring-3   (28)
Spring-4   (28)
Spring-5   (28)
Spring-6   (28)
Spring-7   (28)
Summer-S   (30) Summer Solstice on the 20th
Summer-2   (30)
Summer-3   (30)
Summer-4   (30)
Summer-5   (30)
Summer-6   (30)
Autumn-E   (28) Autumn Equinox on the 18th
Autumn -2   (28)
Autumn-3   (28)
Autumn-4   (28)
Autumn-5   (28)
Winter - S   (28) Winter Solstice on the 21st
Wanderers (13 sols) - End of year Mars-wide vacation, will be 11 sols in leap years (every 5 M-years).

Total 669 sols.

All months are 28 days long except the summer months which are 30 days long, plus a special end of year 13 day Wanderers Holiday period, total 669 sols.

Since 1 Mars sol = about 1.027 Earth days, the month lengths on Mars will be about 29 or 31 Earth days, which might come in handy as the months on Earth and Mars will pass at approximately similar rates.
 
There are 5 autumn months, 5 winter months, 7 spring months and 6 summer months, reflecting the fact that unlike Earth, on Mars the seasons do not have the same lengths.

I have not named any of the months, the names above are placeholder names. Winter-S is the month when winter starts on the winter solstice, and Winter-2 is the second winter month, and so on.

There is a 13 day end-of-year Wanderers Holiday period after the winter solstice month and before new Mars Year's Day which will hopefully be used by Martians to travel and explore their planet together in groups. (13 days + 1 new year's day = 14 sols or two weeks annual holiday for everyone)

Every 5 years is a leap year and the Wanderers Holiday period will be shorter (11 days). With this -2 sols per 5 years adjustment, the calendar drift is very slow: it gains 1 sol every about 220 1,100 Mars years.

So summing up, the Sol is divided in 24 Mars hours of 60 Mars minutes each, but the Mars minute has a special length of 61.6494751 Earth seconds, and the Martian Year is divided into 24 periods of which 23 are normal length but one is a special 13 day holiday period just before the end of the Martian year.

Note: 'Wanderers' is the title of the Introduction to Carl Sagan's Pale Blue Dot: A Vision of the Human Future in Space which ideally will be a school textbook for kids on Mars.
« Last Edit: 11/10/2016 04:43 AM by Lumina »

Offline Paul451

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Re: Mars Timekeeping System
« Reply #120 on: 11/10/2016 05:18 PM »
If you're going to have leap-hours, why not alternate between 24 and 25hr sols? That way you can at least use whole hours, as well as whole minutes.
People won't adjust to different day length. The 1 hour switch twice a year for daylight saving is bad enough.

....in a thread where people are arguing for a minute with 61.6494751 seconds?

But remember, I was replying to someone who proposed a day-length that altered between 24h30m and 24h40m.

daylight saving is bad enough. Many, like me, want to get rid of it.

Aside: daylight savings is a least-worst kludge to deal with a varying day length. Back in the day, everyone would just wake with the dawn and the day would evolve around that. Dawn plus two hourglass turns. And for similar reasons, it makes sense to change the operating hours of schools/stores/govt-agencies/businesses/etc with the change in day-length. But with a fixed clock and hence artificially fixed school and business hours, it's easier to change the clock itself than the chaos of trying to change the other things individually.

Either just keep the length of the earth year, with a few less days to adjust for the longer days

Logically, that's what people would do. However, given the insistence that we "must have" (dates in Martian years, pseudo-months, pseudo-hours/min/sec), I suspect that some bombastic administrator/governor in the early Mars colony will create something convoluted and weird that everyone will get trapped with for centuries after.

My preference is to just use the Sol and decimal fractions thereof.¹ (And no, before anyone jumps in again, not 10 "hours" per Sol, 100 "minutes" per hour, 100 "seconds" per minute.) But it surprises me how easily the Mars rover scientists adopted a slightly length second (given that if anyone was going to object, it would be scientists). So that may be the solution that just happens, no matter how many "clever" (and hideously complex) systems we nerds come up with. You set an informal Mars-second, separate from the SI Second, and then keep the familiar 24/60/60.

¹ Combined with a simple sol-count year, a calendar-clock display (or time-stamp) would be "374.513..." to whatever precision you need. The nerd in me is deeply sated by that.
« Last Edit: 11/10/2016 05:20 PM by Paul451 »

Offline Paul451

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Re: Mars Timekeeping System
« Reply #121 on: 11/10/2016 05:40 PM »
Paul451, just counting Sols (which we already do) without engaging the tougher problems is a copout,

A "copout" of "engaging the tougher problems"? Creating a system of pseudo-months doesn't carry some moral superiority.

and your proposal to alternate 24h with 25h days is a nonstarter given that sunrise would move several minutes each day.

{laughs} The time of sunrise/sunset already moves each day, that's unavoidable on a planet with axial tilt. That's why detailed weather forecasts usually include tomorrow's time-of-sunrise/sunset (and sometimes moonrise/set); because the kind of people who need detailed weather forecasts (pilots/fishermen/etc) - and only those people - also need to know the precise time of sunrise/sunset.

But I'll point out again that I was replying to someone (MP99) who had suggested having system that varied between 24h30m and 24h40m length Sols. I literally said "if you are going to have..." as the first words in my post. Ie, if you are going to have a variable-length day, at least keep it to whole hours.

Do you have any serious proposals for subdividing the length of a Sol and the length of the Martian year into smaller units?

Counting Sols over the year is the only human-friendly system.

People can cope with seasons and other regular events being tracked by a Sol-count rather than named pseudo-months. Even fairly innumerate people can remember that "Winter starts somewhere in the 400's".

[It's worth pointing out that our calendar isn't based around seasons/solstices/equinoxes. We mark seasons/solstices/equinoxes/anniversaries/holidays by the calendar, just as we could with any calendar, we don't mark the calendar by the equinoxes (which is why they vary each year.) Historically, our calendar was meant to be based on equinoxes, starting exactly 25 days before the vernal equinox, and originally with "winter" officially being after December and not recorded on the calendar at all. Ten named months over 304 days, with 61 days unnumbered and unnamed.]

Just counting Sols it means that anyone can impose super-Sol units that fit their needs, without worrying about trying to sync it up to the convoluted and artificial "Martian calendar" (for example, FIFO workers at outposts might be on a 10/5 cycle, others on 20/10. Shift-work schedules might cycle over 30 Sols, or 50, or 70 (if they keep using 7-day weeks informally.))

And it avoids those unnecessary left-over Sols in most proposals. (You still need one leap-Sol every five years, that's baked in to the Sol/Year divisor and unavoidable. But making an odd 13 or 7 or 5 Sols gap a regular part of every calendar just so you can have pretend-months is hardly "solving" the problem.)

As for sub-Sol, I've already repeatedly said I prefer using the Sol itself as the metric in a simple decimal system. But if scientists can cope with having a different informal second at the same time as they use the SI Second, then I can accept a slightly stretched 24hr Mars-clock as the least-worst kludge.

Offline Paul451

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Re: Mars Timekeeping System
« Reply #122 on: 11/10/2016 06:05 PM »
Just for fun, I was wondering how long it would take to change Mars' solar day length to 24 Earth hours by firing raptors due west from the top of the southern rim of Pavonis Mons

A practice run for changing Earth's year to exactly 364 days, and the lunar rotation to exactly 28 days?

Offline Lumina

Re: Mars Timekeeping System
« Reply #123 on: 11/10/2016 09:56 PM »
So you have 3 newly defined units (Mars day, Mars Hour, Mars minute) instead of just one (Mars day, or sol). This is crazy.

Whether having a new minute on Mars with more seconds than Earth's minute is on balance a good thing or a bad thing, who knows. If it turns out to be good, what I posted is one possible system that can be built off of it. If it turns out not good for some subtle reason, shrug, I had fun dreaming it up.

Since some people are posting against it without offering anything other than the copout, I will let Richard Feynman give us some food for thought on whether a minute with fractional number of seconds is intrinsically evil, with his interesting perspective on perfect and nearly-perfect symmetry:

Quote from: Richard Feynman in Six Easy Pieces
“So our problem is to explain where symmetry comes from. Why is nature so nearly symmetrical? No one has any idea why. The only thing we might suggest is something like this: There is a gate in Japan, a gate in Neiko, which is sometimes called by the Japanese the most beautiful gate in all Japan; it was built in a time when there was great influence from Chinese art. This gate is very elaborate, with lots of gables and beautiful carving and lots of columns and dragon heads and princes carved into the pillars, and so on. But when one looks closely he sees that in the elaborate and complex design along one of the pillars, one of the small design elements is carved upside down; otherwise the thing is completely symmetrical. If one asks why this is, the story is that it was carved upside down so that the gods will not be jealous of the perfection of man. So they purposely put an error in there, so that the gods would not be jealous and get angry with human beings.
We might like to turn the idea around and think that the true explanation of the near symmetry of nature is this: that God made the laws only nearly symmetrical so that we should not be jealous of His perfection!”

New units aren't bad per se, they are only bad when they make it harder for us to get things done. The Mars Hour is just a derived aggregate of the truly new Martian minute which is a non-integer number of seconds long, chosen such that the "hour" on Mars would continue to be subdivided by 60 "minutes". So I would agree with you that the Mars minute is not a nice thing and it has disadvantages, but I respond that this was by design after a cost-benefit mental exercise, so that all other time units on Mars (acual SI length of a second, 60 subunits to the hour, 24 subunits to the sol) would be familiar relative to what we do on Earth.
« Last Edit: 11/10/2016 10:25 PM by Lumina »

Offline Lumina

Re: Mars Timekeeping System
« Reply #124 on: 11/10/2016 10:08 PM »
My preference is to just use the Sol and decimal fractions thereof.¹ (And no, before anyone jumps in again, not 10 "hours" per Sol, 100 "minutes" per hour, 100 "seconds" per minute.) But it surprises me how easily the Mars rover scientists adopted a slightly length second (given that if anyone was going to object, it would be scientists). So that may be the solution that just happens, no matter how many "clever" (and hideously complex) systems we nerds come up with. You set an informal Mars-second, separate from the SI Second, and then keep the familiar 24/60

The Mars Rover scientists adopted a slightly longer second? How interesting! They must be even crazier than me because a stretched Mars second means they have four new units to my "crazy" three: the long Mars second which isn't really a second, the long Mars Minute which isn't really 60 seconds long, the long Mars Hour which isn't really 60 minutes long and the long Mars day which isn't really 24 hours long.


« Last Edit: 11/14/2016 07:33 PM by Lar »

Offline rocx

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Re: Mars Timekeeping System
« Reply #125 on: 11/11/2016 09:08 AM »
It seems to me we are starting to exhaust the possible solutions, and most systems come down to a few simple choices between solutions for basic problems. And the choice mostly comes down to preference, which I think should be solved by putting up a poll on this forum, and of course later among the Mars colonists.

Sols and days are not the same length
Suggested solutionAdvantagesDisadvantages
Change length of secondKeeps mental arithmetic the sameBreaks SI units
Add time at end of minute/hourKeeps arithmetic mostly the sameWeirdness at end of minute/hour
Add time at end of solSame time lengths as on EarthBroken hour at end of sol
Leap hours at some solsNo broken time unitsMemorise leap rules

Earth weeks are less meaningful (no 1/4 of moon orbit)
Suggested solutionAdvantagesDisadvantages
Discard them all togetherSimplicityLack of repeating oppurtunity for rest or celebration
Have seven sol weeksKeep Earth labor customsNot synchronous with Earth
Introduce other length of weekMay be more suitableBreaks traditions
Track Earth weeksEasier collaboration with EarthLeap sols in weeks

Earth months are not meaningful
Suggested solutionAdvantagesDisadvantages
Discard them all togetherSimplicityYear becomes monotonous
One month for every sol-day differenceDay of month gives Earth timezones.Does not divide nicely in weeks or year.
Divide Mars year in unequal monthsBetter reflects season variabilityMore difficult arithmetic
Have months of about 30 solsKeep Earth labor customsMore months in a year
Track Earth monthsEasier collaboration with EarthMonths in different time of year

Earth years are not meaningful
Suggested solutionAdvantagesDisadvantages
Sidereal yearTracks seasonsMay not be most relevant
Synodic periodTracks launch windowsDoes not follow seasons
Earth yearsEasier collaboration with EarthNot relevant on Mars surface

So four choices to make, with 3-5 options for each one. We could probably design a functional calendar for every combination of choices. My personal preferences are added time at the end of the day, seven-sol weeks, no months, and synodic years. Let me know if I missed an important choice.
« Last Edit: 11/14/2016 08:44 AM by rocx »
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Offline Nilof

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Re: Mars Timekeeping System
« Reply #126 on: 11/13/2016 10:03 PM »
One thing worth mentioning is that it takes roughly 38 sols or 39 days for the Mars clock to wrap around the Earth time zones. Furthermore, 79/77 days is a very good approximation for the length of one sol.

So I propose Mars months alternating between 38 and 39 sols with the odd adjustment needed a few times per century. These Martian months would have the special significance of being the synodic period between Mars sols and Earth days, so that knowing the sol of the month tells you exactly what Earth time zone you are closest to.

My personal preference is:
* Added time at end of day, or Mars-specific subdivisions of the day with their own words.
* Seven-sol weeks
* Months alternating between 38 and 39 sol, allowed to drift away from the year just like weeks or lunar months.
* Synodic years.

A nice feature of the seven-sol week is 11 martian weeks in two martian months, so they are related.

(EDIT: accidentally used sidereal days instead of sols here, see post below for corrected numbers).
« Last Edit: 11/25/2016 12:59 AM by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline ccdengr

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Re: Mars Timekeeping System
« Reply #127 on: 11/14/2016 03:59 AM »
all along you knew that JPL has been stretching the second (and therefore everything else above it) for years now.
JPL uses a stretched second only in very specific contexts to produce local mean solar time at the landing sites, which has a certain mnemonic value for keeping track of when the sun is up.  SI units are still used for practically everything and the rover clocks are running in SI (nominally, they drift a little).  See http://naif.jpl.nasa.gov/pub/naif/MSL/kernels/sclk/msl_lmst_gc120806_v3.tsc for details.

Offline rocx

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Re: Mars Timekeeping System
« Reply #128 on: 11/14/2016 07:39 AM »
One thing worth mentioning is that it takes roughly 38 sols or 39 days for the Mars clock to wrap around the Earth time zones. Furthermore, 79/77 days is a very good approximation for the length of one sol.

So I propose Mars months alternating between 38 and 39 sols with the odd adjustment needed a few times per century. These Martian months would have the special significance of being the synodic period between Mars sols and Earth days, so that knowing the sol of the month tells you exactly what Earth time zone you are closest to.

My personal preference is:
* Added time at end of day, or Mars-specific subdivisions of the day with their own words.
* Seven-sol weeks
* Months alternating between 38 and 39 sol, allowed to drift away from the year just like weeks or lunar months.
* Synodic years.

A nice feature of the seven-sol week is 11 martian weeks in two martian months, so they are related.

A very well thought out proposal! I have added it to the table, and I support it, so we share all the same preferences.
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Offline Paul451

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Re: Mars Timekeeping System
« Reply #129 on: 11/14/2016 07:46 AM »
Furthermore, 79/77 days is a very good approximation for the length of one sol.

It feels like you were going to do something with this part, and then didn't.
« Last Edit: 11/14/2016 07:46 AM by Paul451 »

Offline mikelepage

Re: Mars Timekeeping System
« Reply #130 on: 11/14/2016 08:18 AM »
One thing worth mentioning is that it takes roughly 38 sols or 39 days for the Mars clock to wrap around the Earth time zones. Furthermore, 79/77 days is a very good approximation for the length of one sol.

So I propose Mars months alternating between 38 and 39 sols with the odd adjustment needed a few times per century. These Martian months would have the special significance of being the synodic period between Mars sols and Earth days, so that knowing the sol of the month tells you exactly what Earth time zone you are closest to.

My personal preference is:
* Added time at end of day, or Mars-specific subdivisions of the day with their own words.
* Seven-sol weeks
* Months alternating between 38 and 39 sol, allowed to drift away from the year just like weeks or lunar months.
* Synodic years.

A nice feature of the seven-sol week is 11 martian weeks in two martian months, so they are related.

Interesting observation, but I'm not sure I understand why syncing up with Earth time zones is important? It's not like anyone is going to be having real-time telephone conversations.  79/77 is a pretty odd fraction, so it's also not like it would be easy to remember.  Lastly, looks to me like your 38/39 sol months don't divide evenly into the year..?

668.6 sols (687 days) per Martian Year
759.1 sols (780 days) per Earth-Mars synodic

Just looking through the Darian calendar on wikipedia, I get the use of weekday names as a concession to tradition. But as far as months go, lunar months are a product of Earth calendars, and I think Martian months should be something explicitly useful to Martians, not just abstract periods of 4 weeks/5.5weeks etc. 

What I came up with was a calendar where the Earth-Mars synodic period shifts by an integer number of months each Martian year. 

There's a difference of 91 sols between the year and the synodic period, so I've divided the year into 22 months which alternate in a 31/30/30 pattern, except for the last month which also has 31 sols.  As far as leap years go, you get 3 days behind every 5 years, so you could add 3 days to the final month of the 5th year.



As far as intraday periods go, my preference is keeping the SI unit for seconds, and keeping 24 units in a sol (so you can set up a time-zone period on Mars eventually).  So I guess that means altering either minutes or hours.  You could even have a construct where you add 3 seconds to every even-numbered minute - still kludgey.
« Last Edit: 11/14/2016 08:28 AM by mikelepage »

Offline rocx

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Re: Mars Timekeeping System
« Reply #131 on: 11/14/2016 08:41 AM »
One thing worth mentioning is that it takes roughly 38 sols or 39 days for the Mars clock to wrap around the Earth time zones. Furthermore, 79/77 days is a very good approximation for the length of one sol.

I actually calculated this now, and to me it looks to be wrong. 1 sol equals 1,02749 days, so 36 sols equals 36,990 days. In practice, this means two 36-sol months followed by a 37-sol month, and sometimes one 36-sol month followed by a 37-sol month. Almost 21 of these months would fill up a synodic period. I don't see any easy way to link it with seven-sol or seven-day weeks, so they will have to drift.
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Offline mikelepage

Re: Mars Timekeeping System
« Reply #132 on: 11/14/2016 08:45 AM »
I'd add that you do want your calendar to keep track of Martian years, not just synodic periods, because the martian season you are in will directly affect how much light you're receiving on your solar panels.

Offline DreamyPickle

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Re: Mars Timekeeping System
« Reply #133 on: 11/14/2016 09:51 AM »
It seems that 79/77 was incorrectly calculated to be close to a martian sidereal rather than solar day. It's still an interesting idea because the cycle it takes for solar time at Hawthorne and the colony to resync can make the difference between getting an email reply in 1 hour or overnight. This 36 or 37 sol period will be meaningful for work habits.

291 sols is equal to 298.999954 days (much closer than 79/77) so you can have a very stable pattern with 5 36-sol and 3 37-sol martian months. Something like 36 + 36 + 37 + 36  +36 + 37 + 36 + 37 + repeat.

On earth seasons are important because they are closely correlated to weather and the life cycle of plants. On Mars all this will affect is a fluctuation in solar power production. Synods will be more relevant because they are tied to launch windows and the light delay in communication with earth. Even for non-realtime communication the difference between a 8-minute and a 48-minute roundtrip is significant. Every synod you might also have to deal with reduced bandwidth when Mars and Earth are at opposition.

Online guckyfan

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Re: Mars Timekeeping System
« Reply #134 on: 11/14/2016 10:25 AM »
The lunar calender is still widely in use on earth and is not related to the seasons. No need to have a martian calender coupled to the martian year.

Offline Nilof

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Re: Mars Timekeeping System
« Reply #135 on: 11/14/2016 10:37 AM »
Furthermore, 79/77 days is a very good approximation for the length of one sol.

It feels like you were going to do something with this part, and then didn't.

I did. 38 + 39 sols = 77 sols. But I accidentally used the figure for sidereal instead the figure for solar martian days so as noted above the actual numbers do need some readjusting. For solar days, the sol/day ratio can be expressed as a continued fraction [1 ; 1, 36, 2, 1, 1, 1, 64, 2, 1, 2 ...] which gives the following sequence of convergents(best rational approximations):

1, 37/36, 75/73, 112/109, 187/182, 299/291, 19323/18806 ...

So as noted the length of a Martian month should actually be closer to 36 sols, which can be kept in sync by alternating between 36 and 37 sol months according to some pattern. The first order correction is to just straight up alternating between 36 and 37 on consecutive months, but that can be improved on. A 291-day cycle with five 36-day months and three 37-day months should stay accurate without any leap days needed for a very long time because the next term in the continued fraction is quite big.
« Last Edit: 11/25/2016 12:58 AM by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline mikelepage

Re: Mars Timekeeping System
« Reply #136 on: 11/14/2016 12:29 PM »
On earth seasons are important because they are closely correlated to weather and the life cycle of plants. On Mars all this will affect is a fluctuation in solar power production. Synods will be more relevant because they are tied to launch windows and the light delay in communication with earth. Even for non-realtime communication the difference between a 8-minute and a 48-minute roundtrip is significant. Every synod you might also have to deal with reduced bandwidth when Mars and Earth are at opposition.

?!?!  In summer, Mars Opportunity rover gets ~700Wh per day.  In winter, ~300Wh per day.  If anything the yearly/seasonal fluctuation in solar power will have more impact on Martian colonists long term than anything they get from Earth ::)  Power is life-support, grow lights for food production, and ISRU etc.   

Not to say synods aren't important (especially early on), but the Martian year will only grow in importance, and any calendar that is useful will make it easy to determine both cycles.

Offline Robotbeat

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Re: Mars Timekeeping System
« Reply #137 on: 11/14/2016 12:47 PM »
Until nuclear power is used.
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Offline Nilof

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Re: Mars Timekeeping System
« Reply #138 on: 11/14/2016 12:56 PM »
On earth seasons are important because they are closely correlated to weather and the life cycle of plants. On Mars all this will affect is a fluctuation in solar power production. Synods will be more relevant because they are tied to launch windows and the light delay in communication with earth. Even for non-realtime communication the difference between a 8-minute and a 48-minute roundtrip is significant. Every synod you might also have to deal with reduced bandwidth when Mars and Earth are at opposition.

?!?!  In summer, Mars Opportunity rover gets ~700Wh per day.  In winter, ~300Wh per day.  If anything the yearly/seasonal fluctuation in solar power will have more impact on Martian colonists long term than anything they get from Earth ::)  Power is life-support, grow lights for food production, and ISRU etc.   

Not to say synods aren't important (especially early on), but the Martian year will only grow in importance, and any calendar that is useful will make it easy to determine both cycles.

Well, one option would be using months to track that by having the months follow a 764-sol (785-day) calendar with 13 36-day and eight 37-day months, which would be roughly as long as one synod. 785/764 is a somewhat worse approximation than 299/291 for the sol/day ratio (should drift by five minutes per cycle instead of five seconds per cycle) but still good enough for practical purposes, and that way you could use the month cycle to both keep track of the synods and to convert between Mars and Earth time zones.

The transfer windows would drift by a few days on the calendar for each synod, but that probably won't be that much of a problem. I'd expect improvements in propulsion to widen the launch windows by more than their drift on the calendar, and you don't really need more than a rule of thumb.

So then you'd be left with:

* A Synodic calendar with months that help you convert between Earth and Mars time zones, and approximately keeps track of launch windows.
* A Seasonal calendar that keeps track of Mars seasons.

Alternatively, instead of having a fixed calendar with 764 sols, you could just keep the five month cycle and have a rule of thumb where you have 21 martian months (764 or 765 sol) in one synod. Synods, months, and years would then be decoupled.
« Last Edit: 11/14/2016 02:06 PM by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline DreamyPickle

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Re: Mars Timekeeping System
« Reply #139 on: 11/14/2016 05:03 PM »
Well, one option would be using months to track that by having the months follow a 764-sol (785-day) calendar with 13 36-day and eight 37-day months, which would be roughly as long as one synod. 785/764 is a somewhat worse approximation than 299/291 for the sol/day ratio (should drift by five minutes per cycle instead of five seconds per cycle) but still good enough for practical purposes, and that way you could use the month cycle to both keep track of the synods and to convert between Mars and Earth time zones.

The martian synod is closer to 760 sols long, 4 sols makes it way off. There is really no relation between earth-mars synods and earth-mars solar time synchronization and it would make more sense to track them separately.

Martian weeks seem like a good idea but they will quickly get out-of-sync with earth weeks so you get in the situation where the martian weekend rest period falls in the middle of the earth work week. This could be fixed by inserting 6-sol weeks every 4 or sometimes 5 regular 7-sol weeks.

Honestly I think that simply tracking "Synod X SOL Y" with fixed 7-sol martian weeks would be sufficient.

Offline Lar

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Re: Mars Timekeeping System
« Reply #140 on: 11/14/2016 07:35 PM »
This thread seems to have brought out some less than excellentness. Some trimming. Might not have got it all but that's not a license to snap back.

Be excellent to each other.  All the time, every time. Time threads are not exempt.
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Offline mikelepage

Re: Mars Timekeeping System
« Reply #141 on: 11/15/2016 03:53 AM »
This thread seems to have brought out some less than excellentness. Some trimming. Might not have got it all but that's not a license to snap back.

Be excellent to each other.  All the time, every time. Time threads are not exempt.

Indeed, lest the trip to Mars become a bogus journey. (sorry, best I could come up with)

I tend think the 7 day week is going to become another one of those things like that old chestnut about the width of the Shuttle SRBs being defined by the width of a horse's ass.  Same with the second (being an SI unit), and UTC for just about everywhere, unless it's more useful to use a specific local time because of a specific local cycle like a planet turning on it's axis or orbiting the sun.


Offline baldusi

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Re: Mars Timekeeping System
« Reply #142 on: 11/15/2016 06:45 PM »
The week is more of a human necessity regarding leisure. Having workdays and weekends is a psychologically important feature of the calendar. Make it too short and your leisure days are too much in proportion. Make it too long and you end up exhausted by the end of the week.
Yes, adults most probably could very well have a 10 day week. But kids would then need 3 day break from school. And the longer the week the more difficult to make an invariant year.
Personally, I don't see why the synodic Earth-Mars cycle should be the base. Is not like it won't be handled by people expert in astronavigation. Simple time is important for normal life.
I'm trying to get the length of the synodic sol through Mars orbit. Anyone has a page or calculator that can give me the angular motion of an orbit? I.e., I want to know each 88642.6632 seconds how many degrees has Mars moved with respect the longitude of the ascending node.

Online Norm38

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Re: Mars Timekeeping System
« Reply #143 on: 11/15/2016 10:37 PM »
I personally always liked the KSR timeslip to deal with the extra length of the day, but to me it doesn't make sense to have it be right at midnight.  Too many people are still active then.  I would have it occur around 2am-4am, when almost everyone is sleeping. Most everyone gets extra sleep, and have no discontinuity.  For those who are working 3rd shift, their shift would either end early, or they'd have it as an extra break or something.
For Jim's concerns about time zones and conference calls, I've been on global 3-way calls between Chicago, Germany and Hong Kong.  We pick a time that isn't during the middle of the night for anyone. The timeslip at 3am makes the most sense to me.

I don't see how anyone can mess with seconds, minutes, hours, given how intimately they tie into all units of measure for physics.

Offline rocx

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Re: Mars Timekeeping System
« Reply #144 on: 11/16/2016 07:42 AM »
I personally always liked the KSR timeslip to deal with the extra length of the day, but to me it doesn't make sense to have it be right at midnight.  Too many people are still active then.  I would have it occur around 2am-4am, when almost everyone is sleeping.

That is the case on Earth in temperate zones, where the evening is a lot warmer than the morning. Mars has a lot less atmosphere, so it would make more sense to have the sleep pattern follow the amount of sunlight. In that case local midnight would be the middle of the sleep period.
Any day with a rocket landing is a fantastic day.

Online Norm38

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Re: Mars Timekeeping System
« Reply #145 on: 11/16/2016 04:23 PM »
But Mars has a tilt just like Earth, so the length of the day is always changing.  No one gets up with the sun anymore and goes to bed at sunset.  That went out with the advent of artificial light.  As Mars colonists will be mostly living underground for a variety of reasons, I don't see that daylight is going to have that much effect.

But why wouldn't sleep patterns stay focused around local noon?  That means that working hours fall between 6am - 6pm. And because humans don't need 12 hours of sleep a day, people stay up after working hours for another 4-6 hours.

If you shift everything by 3 hours, then working hours are 3am - 3pm and people are going to bed between 7pm and 10pm.  It's less centered on daylight.  But those are the details best left to the actual colonists I guess.

Offline Oersted

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Re: Mars Timekeeping System
« Reply #146 on: 11/28/2016 09:45 PM »
Personally, I don't see why the synodic Earth-Mars cycle should be the base. Is not like it won't be handled by people expert in astronavigation. Simple time is important for normal life.

I totally agree. I also think Synodic Earth-Mars cycles will be abolished from Martian calendars as soon as the Colony declares independence from the Mother-planet!

Offline Dao Angkan

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Re: Mars Timekeeping System
« Reply #147 on: 03/24/2017 12:50 AM »
Fiscal years are generally 52 weeks of 7 days, with a 53 week year every 5-6 years (5.6 on average), the extra week generally falls in December, although some systems use January. For Martian years the equivalent would be roughly alternating years of 95 and 96 weeks of 7 sols. The average would be every 1.945 Martian years, so slightly more frequent than 53 week Earth fiscal years, but in-line with Earth leap years.

That also divides nicely, with 24 months of 4 weeks in 96 week years, but with the 24th month having only 3 weeks in 95 week years.

January - December could repeat every half year, months would have to be denoted with something like H1 and H2 or equivalent.

« Last Edit: 03/24/2017 01:17 AM by Dao Angkan »

Offline CuddlyRocket

Re: Mars Timekeeping System
« Reply #148 on: 03/25/2017 01:19 AM »
January - December could repeat every half year, months would have to be denoted with something like H1 and H2 or equivalent.

Well, if we need to distinguish which particular January we're talking about - as opposed to the instant one - we do so by reference to the calendar year number. So last January was January, 2017; the one before that was January, 2016 etc. So, if you repeat the Jan-Dec monthly cycle twice per Martian solar year, then instead of numbering the years, you could number the half-years instead. The first H1 and H2 would be half-years ('demi-years', 'annums', some other terminology) 1 and 2; the second H1 and H2 would be 3 and 4; then 5 and 6 etc. You could tell whether you were in H1 or H2 simply by whether the half-year number was odd or even!

Offline Space Ghost 1962

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Re: Mars Timekeeping System
« Reply #149 on: 03/25/2017 03:01 AM »
One try here for this low quality thread.

Timezones and time complexity is fading away. Technology is to blame.

Your watch replacement is your communication device. It (along with other devices and virtualizations/cloud) handles time management/translation/reservation/planning/dependencies.

So you're left with a time naming convention (which we already have) to work the technology, and a LMST (Local Mean Solar Time) personal convention that's location based, determinable by the technology.

The rest has no meaning or need anymore. Why invent more time nonsense when the need for it has vanished, and the remainder of the prior is fading away.

Man is a naming creature. But names survive out of need and purpose. Where is the need?

Offline Dao Angkan

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Re: Mars Timekeeping System
« Reply #150 on: 03/26/2017 08:18 PM »
January - December could repeat every half year, months would have to be denoted with something like H1 and H2 or equivalent.

Well, if we need to distinguish which particular January we're talking about - as opposed to the instant one - we do so by reference to the calendar year number. So last January was January, 2017; the one before that was January, 2016 etc. So, if you repeat the Jan-Dec monthly cycle twice per Martian solar year, then instead of numbering the years, you could number the half-years instead. The first H1 and H2 would be half-years ('demi-years', 'annums', some other terminology) 1 and 2; the second H1 and H2 would be 3 and 4; then 5 and 6 etc. You could tell whether you were in H1 or H2 simply by whether the half-year number was odd or even!

I like that, "demi-years" would be close(ish) to Earth years (~345.5 days) during 48 week demi-years (a bit shorter every 4 demi-years), which is a good unit of time for contracts, anniversaries, sporting events etc. 18 Martian demi-years = ~17 Earth years, so you would have birthdays slightly more often, but that might make up for lower life expectancy :P

You would still need a unit for full years, but that could be something simple such as 1/2, 103/4, 2017/8 etc.

It turns out that I'm not the first to propose a "skip year calender". Šuráň, Josef, 1997;

http://adsabs.harvard.edu/abs/1997P%26SS...45..705S

Quote
Abstract
In a generalized approach to calendar construction for Earth, two types of perpetual calendars (with dates fixed to the days of a week) were studied for Mars: with leap and skip days; and with leap and skip weeks. Calendars with skip days or weeks (omitted days or weeks) are preferable, because the frequency of skip years is appreciably lower than that of leap years. Unlike our terrestrial (Gregorian) calendar with a 2-parametric leap rule (periods of 4 and 400 years), a Mars calendar of comparable accuracy requires a 3-parametric rule with three periods. The rules derived possess this accuracy and represent an optimum solution. With the skip week calendar, which appears to be the best compromise for a calendar for Mars, an error of 1 day would occur (theoretically) in an interval >100,000 Martian years. (However, unknown secular changes in the length of the Martian year, an inaccuracy in the adopted value of its length, and possible non-uniform rotation of Mars, may affect the calendar accuracy over such long intervals of time.) A common year would have 672 Martian days distributed into 24 months of 28 days (of 4 weeks of 7 days each). In skip years a week at the end of the twelfth month would be omitted. The above most regular arrangement of months (corresponding to 12 bi-months) and a 7 day Martian week, also offer the possibility of conveniently adapting terrestrial month and day names to the calendar of Mars. The month names could be, e.g. Januarione, Januaryide; Februarione, Februaryide, etc., and those for days, e.g. Mondim, Tuesdim, etc.
« Last Edit: 03/26/2017 08:32 PM by Dao Angkan »

Offline Dao Angkan

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Re: Mars Timekeeping System
« Reply #151 on: 03/27/2017 12:01 AM »
I liked Jim's idea of stretching the last hour of the day rather than inserting a time-slip.  But then I realized that if this is combined with time zones it gets confusing again, as each time zone would be stretching an hour at a different global time.

How about say each hour consists of 61 minutes and 39 seconds?  24 such hours add up to the correct total, all hours are the same length everywhere on Mars, your computerized wristwatch does the math, and time zones are possible.   You would hardly notice the difference for most human activities.   But if you are timing a critical process, navigation, rocket launches, better just use units of seconds, just like the SI system is supposed to.   I remember in the "Orbiter" space simulation program, all timestamps are in seconds, so you get things like "Launch will be at 57,322.7 seconds"

Alternately, define the 'minute' to be a tiny bit longer, rather than the hour.  It works out the same.

I think that this is the best compromise. There shouldn't be a unit which changes depending on the time of day (such as having the last hour of every day run longer or shorter). 24 is also a good number for dividing, for example 360° / 24 = 15°. A day divided by 24 is probably more practical, even though 25 is slightly closer to an Earth hour. There are also very good reasons for keeping the second. So that leaves adjusting either the minute or the hour. I think that the shorter the time period, the higher the level of precision needed (you have less time to check on a 3 minute boiled egg than a 3 hour roast chicken), so it's probably best to adjust the hour.

A 60:99 hour (it might be more memorable to see it on a clock that way than 61:39) would require a "skip minute" (I think it's preferable to keep regular changes to round units) every quarter (according to the "skip week calender"), with the accumulated non-regular spare seconds skipped every skip year (roughly every 191 weeks). It should never go out of sync by much more than a minute.
« Last Edit: 03/27/2017 12:12 AM by Dao Angkan »

Offline oldAtlas_Eguy

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Re: Mars Timekeeping System
« Reply #152 on: 03/27/2017 05:22 PM »
Time standards dependent used measurements:

Ground and aero velocity - km/hr or miles/hr.

liquid flow rates - gallons/minute or L/minute.

RF - cylcles per second (Hz)

So the adjustment of these three affect the scientific everyday use of the value systems.

Offline JasonAW3

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Re: Mars Timekeeping System
« Reply #153 on: 03/27/2017 05:37 PM »
Ok, how about a Martian Sol consisting of 25 hours, each being 59 minutes 11 seconds long?  Sure, you'd have to add a second every 100 sols to keep the clocks right, but that shouldn't be too hard to do.
My God!  It's full of universes!

Offline cwr

Re: Mars Timekeeping System
« Reply #154 on: 03/27/2017 06:26 PM »
Ok, how about a Martian Sol consisting of 25 hours, each being 59 minutes 11 seconds long?  Sure, you'd have to add a second every 100 sols to keep the clocks right, but that shouldn't be too hard to do.

Apologies if this has been covered up thread, but I have a strong suspicion that using UTC on Mars will be important in identifying the epoch of events in the scientific/astronomical world. By that I do not mean that UTC should be used as the Martian calendar but rather that there be an atomic clock on Mars that is synced to UTC.

But that does mean that basic units like seconds, minutes and hours should not be changed from the earth standard.

Carl

Offline A_M_Swallow

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Re: Mars Timekeeping System
« Reply #155 on: 03/28/2017 02:34 AM »
Ok, how about a Martian Sol consisting of 25 hours, each being 59 minutes 11 seconds long?  Sure, you'd have to add a second every 100 sols to keep the clocks right, but that shouldn't be too hard to do.

Apologies if this has been covered up thread, but I have a strong suspicion that using UTC on Mars will be important in identifying the epoch of events in the scientific/astronomical world. By that I do not mean that UTC should be used as the Martian calendar but rather that there be an atomic clock on Mars that is synced to UTC.

But that does mean that basic units like seconds, minutes and hours should not be changed from the earth standard.

Carl


Not only will UTC be used when observing the stars it will also be used when planning flights back to Earth.

Offline TripD

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Re: Mars Timekeeping System
« Reply #156 on: 03/28/2017 03:55 AM »
Instead of repeating January and December, perhaps create two new Mars themed months?   Romuary and Remuary?

Offline Paul451

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Re: Mars Timekeeping System
« Reply #157 on: 03/29/2017 03:23 PM »
January - December could repeat every half year, months would have to be denoted with something like H1 and H2 or equivalent.

Instead of repeating January and December, perhaps create two new Mars themed months?   Romuary and Remuary?

By "January-December" Dao Angkan didn't mean January and December are repeated, he meant the entire 12 months from January to December. If you keep roughly 4 week months, the Martian year is roughly 24 months long.

[The 7*4*24 calendar works out pretty well. You're around 3.4 sols out each year. So, every month is 28 sols long, except every sixth month is 27 sols long. Unless it's the last month of an odd-numbered year or an even year divisible by ten. Unless it's divisible by 1000. Unless it's divisible by 10,000... etc etc.]

Offline gospacex

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Re: Mars Timekeeping System
« Reply #158 on: 03/29/2017 03:46 PM »
Large parts of Earth population aren't using am/pm. It is US-centric. Where I am, in writing time is almost always expressed in 00:00-23:59 system.

Offline Paul451

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Re: Mars Timekeeping System
« Reply #159 on: 03/29/2017 03:53 PM »
For all these elaborate schemes, I'll repeat the question that I've asked of all previous proposals.

Why?

What value is served by copying Earth's lunar-calendar derived months or our Babylonian clock in a system which is just different enough to be pointlessly annoying? It's not "familiarity", since it isn't the familiar system. It not "convenience", since it isn't particularly convenient.

For example, what benefit do these calendars offer over just counting the number of sols in the Martian year?

Your dates could then be written as Years-since-landing/Sols. Eg, M+75/419. 419th day of the 76th year of settlement. You still have leap-years due to the inexact number of Sols in a year, but at least you're not trying to graft Earth's already convoluted conventions onto Mars. (And as I've said previously, it's not hard to remember that the main dust-storm season starts around Sol 400 and runs for 150 Sols.)

In the same way, you could divide the Sol time-of-day into decimal Sols, rather than trying to mutilate Earth's clock to fit. That way you avoid any temptation to screw with the length of hours/minutes/seconds and make everything even more confusing. So the full time-stamp on, say, a message will be something like "M+75/419.450". And the same time anywhere on Mars or in orbit around it. Locally to where you are on Mars, outside sun-up is currently 0.72, with the fixed internal day-cycle lighting of the public areas starting at 0.7 and ending at 0.3.

And I'd prefer to use a Universal Martian Time regardless of where you are on the planet or around it (eliminating time-zones and date-lines to screw up coordination and planning.) IMO, it will probably evolve naturally around the local solar mean time of the first major settlement. Off-site activities, and later satellite settlements, will initially operate on that "base time" for convenience, and it will become entrenched from there. (Unless someone obsessively insists on introducing time-zones - because you have to have time-zones.)



Alternatively...

Why bother at all?

When calendars were created on Earth, the majority of the population was involved in outdoor farming and needed to know when to plant, when to harvest, when to prep, etc. And everyone was affected by seasons and weather. (Even near the equator, you have annual monsoons, hurricane seasons, etc.) And to a large degree, even with modern urban environments, that's still true for most of us. On Earth, the time of year matters.

OTOH, the main variation in "weather" on Mars is dust storms, while the habitats are enclosed and climate controlled. Even crop times are not going to sync up with the Martian year. So Martians don't really need to care about the time of Martian-year, especially if the first settlements are within 30 degrees of the equator, nor care how many Martian-years have gone by. There might be an operational issue with solar power and severe dust-storms, but very few people will be intimately concerned about that, they just need to know to plan around possible storms (power-reductions, maintenance cycles, etc), perhaps starting around September this (Earth) year and running for around five months. Two (Earth) years later, they'll be told it's going to start in July.

In other words, there's not much reason to not just keep using the same Earth calendar even on Mars.

Because Days != Sols, you slip against Earth's days by about one day every 5 weeks. So you can correct the Martian "week" back to Earth's day-of-the-week by skipping a day-of-the-week every fifth week. (And skipping the skipping roughly once per Earth year.)

I'd skip Monday.

That way, Martians can use normal named weekdays, use local time, and never be more than a half day away from UTC, as with any time-zone on Earth. So when it's Tuesday somewhere on Earth, it's always either Tuesday or nearly Tuesday on Mars. When it's March on Earth, it's March on Mars. When it's 2057 on Earth, it's 2057 on Mars.

[edit: Only the Martian time-of-day will be odd, but it must be odd, so again I'd just use decimal-Sols rather than trying to mutate Hours/Minutes/Seconds.]

Yes, this awkwardly tries to graft Earth's already convoluted Calendar onto Mars, but the advantage is that the time and date on Mars would essentially be the same as it is on Earth. (And on the moon, and on free-flying space-stations, and on ships in transit, and throughout the rest of the settled solar system.)
« Last Edit: 03/30/2017 03:20 PM by Paul451 »

Offline Russel

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Re: Mars Timekeeping System
« Reply #160 on: 03/30/2017 11:38 AM »
I've been lurking on this thread for quite some time. Its quite impressive the number of different ways to approach the problem and the number of interesting schemes. What I'd love to see is a taxonomy of the problem that separates out the various components and identifies the easier and harder issues.

For instance, the basic unit of time, the SI second. There seems to be consensus on that (not total). After that it gets more interesting.

The issue of what a Martian clock looks like appears to be separable from the issue of calendars and nomenclature.

And then there are issues of time zones and the like. As if things weren't complicated enough.

Two other issues I'd bring up.

First is that we need to hold separate what a practical system of timekeeping would look like under circumstances where our presence on Mars is purely for scientific and exploratory purposes. Versus, what is a practical system for what could be loosely called a colony. One has a "mission control". The other may not.

Secondly we humans evolved to live essentially outdoor lives. Houses and artificial lighting are very recent constructs. On Mars the presence or absence of sunlight (such as it is through a small window or the visor of your suit) may impact on how people perceive time and how important the day night cycle on Mars is for timekeeping. It also feeds back on the discussions about time zones. And how "natural" it is to think that 12 noon is when the sun is at its highest. Remember lots of people here on Earth live where there are extremes of day length and the clock face is at times an artificial convention.


That being said, the poster that pointed out that convenience rules, probably got it right. That and habit. So here's my take on things.

Ok, We have an SI second. Lock that in. What else? Well, lets start with the big picture. Firstly, in a regime where we are merely explorers and mission control is the final word on things, we are probably going to have Martian Sols and Earth GMT. The fact that each Sol begins and ends at a different point relative to Earth GMT doesn't really matter. We have time pieces and alarms and computers to take care of practicalities. So a Martian explorer will have Sols to organise their mission into and practical timekeeping will be via an Earth clock. Yes a bit weird, but people will rapidly adapt. Especially those who are well trained and well disciplined.

Secondly, has anyone considered how we tend to dive into convention in actually having a clock face? (This is for the colony scenario). Do we need hours? Minutes? These concepts evolved on Earth for various reasons I won't go into here, suffice to say that it wasn't that long ago when most of us didn't really know or care about the precise minute. Its perfectly feasible to have a Martian clock that consists of seconds into a given Sol. Yes, easily factored hours and minutes are great for mental arithmetic, but who uses mental arithmetic for time these days? Dinner will be at 69,300 seconds! Yes it sounds awkward but if you actually did it, people would get used to it and their technology would do the actual work. Now, I'm not saying I'd hate having hours and minutes, just that we need to be aware how arbitrary they are. Besides, if I correctly predict that Earth GMT will be observed as the means of marking time during exploration, then force of habit may carry this practice over to an actual colony. Certainly the arguments for having one single coordinated Mars time have some weight and if you accept this then you're not too far from accepting Earth GMT as that coordinated time. Anyhow from here on I'll talk about an actual colony with non-scientists and tourists.

As far as more "natural" feeling Martian clocks go, there are indeed arguments for carrying over 24 hours as the most basic subdivision. Yes, its a result of being highly divisible. In any case, if you're going to have hours then with all else being equal, familiarity and convenience should be considered. But what about minutes? I'm going to argue we don't need minutes as such. We simply need a convenient method to speak of time and write time. One that has a bit more granularity than using only hours.

My preferred method is to use only hours and seconds. But have a notation that is usable and precise enough for most purposes. The Martian hour would be nearly 3699 seconds. You can express this simply by choosing the two most significant digits and then padding as needed. So:

10:02 hours is 200 seconds past 10:00
16:32 hours is 3200 seconds past 16:00
00:13 hours is 1300 seconds past midnight

Note that the final digit denotes units of 100 seconds. And yes, I understand that some will read this as saying that a Martian "minute" is 100 seconds. I can live with that. What it means is that a (sufficiently precise) clock will have a "tick" or a least significant digit that does represent one exact SI second. The other thing is you don't have to use canonical representation. You can add a further digit (16:324 for example) to add precision if you want. In this case you're saying 3240 seconds past 16:00.

The canonical representation xx:yy has the property that yy gets to 36 and then rolls over to 00. Fractional seconds? That's a problem for the software.

In any case, even if you have a Martian time, there's a very good chance that most timepieces will be dual, with easy access to Earth GMT. Or Earth time in some Earth timezone.

Now there's two other solutions.

1: Using fractional hours. In this case 10:02 represents 10 hours plus 0.02 of an hour (74 seconds). This is workable though its not as easy to have a timepiece that actually "ticks" or counts seconds (though you can certainly add precision).

2: Use a "Martian minute" adjusted accordingly so that each minute is approximately 61.6 seconds. Main advantage is a familiar clock face. It would require a bit of an ugly hack. The digital version would presumably count to 61 seconds then roll. The analog version might keep a conventional third hand but the third hand gets "stuck" for a second and a bit at the top of the minute. The reason I don't like 60 minutes per hour on Mars is because I've never been too fond of it on Earth.

I actually like the concept of "Red Time" but I think it still makes more sense not to have exceptions at such a scale. If the clock needs to be stretched its better done on a finer scale and if we're keeping the SI second then that doesn't leave a lot of choices.



Now we get to calendar issues and it gets more interesting...

I don't think there is a rock solid argument for having named days of the week. There was a poster earlier suggesting that we just need the Sol number relative to the Martian orbit and I have a lot of sympathy with this idea. For one thing, no matter what your special events might be, or what their origin is, Its always possible to locate an event on a given Sol number. Now if you're in the habit of celebrating Earth customs and traditions (mothers day for example) then you simply need to know the Martian Sol that has been chosen as a proxy for the Earth day of the given event. And you mark that in your calendar. Sol 137 this Martian year is mother's day. Done. I'm not saying we have to only have Sols and no other calendar details. I'm just pointing out that being minimalist is a good place to start.

Weeks and months are very problematic because of their Earthly origins. Sure, there's nothing stopping you having a 7 day week on Mars, but why? The origins of 7 day weeks are at least in part due to being able to organise socially and having days in which people can be physically at the same place and time. For instance a day of rest. Note that I steadfastly avoid delving into religious practice here. There's no particular reason to have a 7 day week or to carry over the nomenclature. However, that being said, its a pretty good bet that habit will win the day and Martian Sols will get labelled Monday to Sunday in a cycle.

So I'm predicting, though not strongly advocating that the tradition of seven day weeks and the usual names for days of week will carry over.

Note that in a Martian calendar that simply has Sol numbering and no other subdivisions such as months, having a cycle of days of the week won't cause much drama.

Where the drama really is, is in the creation of months. 12 months in a Martian year? 24? Some other number? The question really has to be asked, do we absolutely need to create months? My contention here is that given a way to resolve time of day and a system of numbering Sols and (if you wish) days of the week, the next thing that is likely to occur is that Martians will continue to use Earth months as a frame of reference and they will have important Earth based events and other baggage. Awkward? Hell yes. But its amazing what people will get used to.

So what will happen is that people will think of mothers day as both being on a specific Martian Sol and at the same time will think of mothers day as being on a particular day in the Earth calendar, along with the name of the month and the day of the month. Thing is, they don't need a Martian calendar to do this, they will anyhow, even in the absence of months in a Martian calendar.

There is an issue of course in that Martian days are a bit longer than Earth days, but the point I'm making here is that there is no need for a one to one correspondence between any given Earth calendar day and a Martian sol. There's two kinds of mapping here. One is from an Earth Calendar day to a Martian sol. This can be done in a formulaic way if desired. The other mapping is from Earth events to Martian sols and this can be done by agreement. For instance if mothers day is chosen to land on an Earth Saturday it may be decided that it is mapped to the nearest Mars Saturday, or the next Saturday, or simply mapped to whatever day of the Martian week is best aligned.

You see what we've done here is carry over Earth related dates and events without actually needing to define Martian months.

To be honest, I've never liked Earth Months. Not just that even today I hate trying to remember their lengths. I've just always been more comfortable with seeing a year as a bunch of weeks. Admittedly on Mars there will be more weeks to a year. But there may not need to be finer grain simply because of the inevitable practice of transplanting Earth based events and mapping them onto Martian Sols. Simply having a week number and day of week may be good enough rather than using the Sol number.

There's also nothing stopping you grouping weeks or having seasons either, again without formal definition of Martian months.

Now the purists that want to keep days of week permanently mapped to sol numbers are lucky because to do so basically means having one odd day left over that doesn't belong to any week. That gives you 98 weeks. And the final day will be a bit leap-year-ish. Now 98 has the factors 2, 7 and 7. Make of that what you wish.

On the issue of time zones. There's an argument for a singular time zone. There's an argument for multiple time zones. I don't think there's really a show stopper either way. This takes me back to the observation. What is life going to be like on Mars? Ok, NASA came up with the idea of an ice bubble habitat. Part of that was to let natural light through (while still providing shielding). Yeah, maybe. But if that's not how settlements are built, who is going to afford a room with a window? I mean that seriously. Windows won't be cheap. And a lot of settlers will spend a lot of their time with no reference to the sun. There's going to be an awful lot of artificial lighting pretending to be natural lighting. It weakens the argument for solar noon. But on the other hand, we have the technology. We can actually have multiple time zones and live quite happily, along with a Martian equivalent of UTC for technical and scientific purposes.


Ok, so where am I at?


1: The SI second
2: A 24 hour clock with no minutes and instead decimal notated seconds.
3: A 687 Sol Martian calendar with weeks and no months.
4: A 7 day week. 98 weeks per year with a fixed relationship between sol number and day of week.
5: A Martian version of GMT/UTC but with local times in operation as well.

So the local time will be quoted as something like

See you at 12:22 on Tuesday, Sol 296.

(Meet you at 2200 seconds plus 12 hours after the start of Sol 296)

Alongside this it will be understood that mothers day is Sol 296 and that happens to correspond to a particular Earth day of the week, day of the month and month.

The point here is that events inherited (rightly or wrongly) from Earth will simply be mapped to a given Mars sol. So you can speak of a given Earth day of the month and calendar month and usually it will be agreed which Mars sol that actually is.

Added to this someone will eventually assign other broader units to the calendar, such as winter and summer. These sub units of the year might be expressed in terms of groupings of weeks, or ranges of sols.

But I think that when people speak of calendar months, they'll actually be referring to Earth calendar months, or their nearest fit in terms of Sol numbers. So it'll be perfectly ok to celebrate someone's birthday on June 22 Earth calendar on the Martian Sol that is the best fit. And usually you'd get 2 birthdays in one Martian year.

Likewise what will pass for "months" on Mars will actually be Earth months that have been mapped to corresponding ranges of sols. So Earth August will be understood as Sol 121 to Sol 151 of this given Martian year. Again, months are not that important for most uses. They're only used for purposes that have reference to what goes on back on Earth. The Martian calendar itself will not have a month. In practice people will think in two calendars.

Finally. Let the software figure out the hard stuff. That's my take on the remaining incongruities.


I'll now spend a moment to defend the above. Firstly, we just can't mess with the definition of a second. As fun as it would be to stretch it. Mars will need science and engineering too.

Secondly, I know there will be objections to decimal notated seconds. The innovation I am suggesting here is the convenient notation. I know that having (what looks like) just under 37 "minutes"* in an hour is going to be sacrilege to some. But to me its the least worst place to hide the issue of day length. I am actually partial to the concept of "Red Time". But when its all said and done, I think we need a regular clock face. Martian hours will be about a minute and a half longer than Earth hours.

Thirdly, I'm trying to be minimalist with the calendar and not import too many complex constructs from Earth. Sols are not a complex concept. And I can live with having regular 7 day weeks. Even though Earth week days were invented for reasons that don't necessarily apply on Mars I don't think they're harmful on Mars. I'm also comfortable with having a stray day to keep a permanent correspondence between day of week and sol number. Your mileage may vary.

Fourth, the issue of months is far too vexed. My argument is that people are just going to import events from Earth and assign them to sols on mars regardless of how the Martian calendar works. So in essence its not necessary to have a more complex Martian calendar than what is being proposed here. Rather people are just going to know that "June" (that is Earth June) happens to be between Sol 232 and Sol 262 in this particular Martian year. In other words for the purpose of local calculation, either the day of the week and the week number, or the sol number is quite sufficient

This doesn't stop you from having other conventions that group weeks or group sols if it has a practical purpose.

Giving up on adding months to the Martian calendar is to me the best way to deal with issues that actually arise from importing events and dates from Earth. Eventually Martian events will be invented and they'll be assigned directly or indirectly to Martian sols. For some there will be two "Junes" this Martian year, harking back to life on Earth. For some the concept of June will only have relevance if they were born back on Earth in June and a month-free Martian calendar will seem natural.

« Last Edit: 03/30/2017 03:48 PM by Russel »

Offline RonM

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Re: Mars Timekeeping System
« Reply #161 on: 03/30/2017 04:10 PM »

Your dates could then be written as Years-since-landing/Sols. Eg, M+75/419. 419th day of the 76th year of settlement. You still have leap-years due to the inexact number of Sols in a year, but at least you're not trying to graft Earth's already convoluted conventions onto Mars. (And as I've said previously, it's not hard to remember that the main dust-storm season starts around Sol 400 and runs for 150 Sols.)

In the same way, you could divide the Sol time-of-day into decimal Sols, rather than trying to mutilate Earth's clock to fit. That way you avoid any temptation to screw with the length of hours/minutes/seconds and make everything even more confusing. So the full time-stamp on, say, a message will be something like "M+75/419.450". And the same time anywhere on Mars or in orbit around it. Locally to where you are on Mars, outside sun-up is currently 0.72, with the fixed internal day-cycle lighting of the public areas starting at 0.7 and ending at 0.3.

And I'd prefer to use a Universal Martian Time regardless of where you are on the planet or around it (eliminating time-zones and date-lines to screw up coordination and planning.) IMO, it will probably evolve naturally around the local solar mean time of the first major settlement. Off-site activities, and later satellite settlements, will initially operate on that "base time" for convenience, and it will become entrenched from there. (Unless someone obsessively insists on introducing time-zones - because you have to have time-zones.)


I think Paul451 is right. You only need to know the local time and date for sunrise, sunset, and seasons. Years, days, and decimal days would work well for that. Use the Gregorian Calendar and UTC for everything else. This system can work for any planet or moon colony.

Offline Paul451

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Re: Mars Timekeeping System
« Reply #162 on: 03/30/2017 04:18 PM »
3: A 687 Sol Martian calendar with no months
4: A 7 day week. 98 weeks per year with a fixed relationship between Sol number and day of week

The Martian year is ~687 days long, but it's 668.6 Sols long.

If you're using 7 Sol weeks, then it's 95 full weeks, plus a few days.



there are indeed arguments for carrying over 24 hours. Personally I think its really convenience that weighs in on this more than anything else

Mutilating the length of the hour to fit 1/24 of a Sol doesn't seem to be convenient to me. It means you have two different units of time, Martian Hours and Earth Hours, plus you have that horrible 3698.... conversion factor even within your Martian hour.

If you're going to do that, why not use an entirely different system that suits Mars, instead of a hack that doesn't?

(Which is why I suggested just using the Sol itself. Divide it decimally, since, you know, that's how we count. It then works with a sol-count calendar, since both systems are base-ten. ie, 507.8 507.9 508.0 508.1... Accurate to as many decimal places as you care about.)

Finally. Let the software figure out the hard stuff. That's my take on the remaining incongruities.

I hear this a lot when people propose complex systems, when trying to clumsily fit Earth-type divisions into Martian time. "Doesn't matter, the computers will handle it!"

I can accept that for converting between Mars dates and Earth dates, but I think its dangerously lazy for Mars timekeeping itself. Someone has to program the time-keeping maths into every one of those devices, or every program on every device, and even something as simple as leap-years has tripped up codes who didn't understand the full system.

3698.9685... seconds in the "hour"? That is going to always screw things up.

IMO, if you system requires that kind of conversion, just within Mars itself, it's a bad system.
« Last Edit: 03/30/2017 04:20 PM by Paul451 »

Offline Russel

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Re: Mars Timekeeping System
« Reply #163 on: 03/31/2017 12:48 AM »
3: A 687 Sol Martian calendar with no months
4: A 7 day week. 98 weeks per year with a fixed relationship between Sol number and day of week

The Martian year is ~687 days long, but it's 668.6 Sols long.

If you're using 7 Sol weeks, then it's 95 full weeks, plus a few days.



there are indeed arguments for carrying over 24 hours. Personally I think its really convenience that weighs in on this more than anything else

Mutilating the length of the hour to fit 1/24 of a Sol doesn't seem to be convenient to me. It means you have two different units of time, Martian Hours and Earth Hours, plus you have that horrible 3698.... conversion factor even within your Martian hour.

If you're going to do that, why not use an entirely different system that suits Mars, instead of a hack that doesn't?

(Which is why I suggested just using the Sol itself. Divide it decimally, since, you know, that's how we count. It then works with a sol-count calendar, since both systems are base-ten. ie, 507.8 507.9 508.0 508.1... Accurate to as many decimal places as you care about.)

Finally. Let the software figure out the hard stuff. That's my take on the remaining incongruities.

I hear this a lot when people propose complex systems, when trying to clumsily fit Earth-type divisions into Martian time. "Doesn't matter, the computers will handle it!"

I can accept that for converting between Mars dates and Earth dates, but I think its dangerously lazy for Mars timekeeping itself. Someone has to program the time-keeping maths into every one of those devices, or every program on every device, and even something as simple as leap-years has tripped up codes who didn't understand the full system.

3698.9685... seconds in the "hour"? That is going to always screw things up.

IMO, if you system requires that kind of conversion, just within Mars itself, it's a bad system.

Oh ok. Knew I'd get one of my figures wrong somewhere. So to maintain a correspondence between sol numbers and days of week would mean having several exceptional days. Mea culpa.

As far as hours goes. Well, I'm ok with the idea of decimal fractions of days. The problem here is that you have to strike a balance between wanting to create something entirely new and clean and wanting to create something that will actually be adopted by real people, familiar with how things are done on Earth.

One problem I identify with decimal fractions of hours is that the least count "tick" of a clock won't be a second. Of course you can have a clock that gives you a separate second "tick" but yeah, I'd rather it be counting real seconds.

The same issue applies to decimal fractions of a day. The least count won't be a second. Again you could provide a secondary second counter. Its not perfect but no I'm not against decimal fractions of a day. I just know thst unless the system were inposed by some authority it probably won't gain acceptance. That's simply my judgement. I've been known to be wrong.

As for the practical issues with time keeping devices. That's going to happen no matter how Martian time is sliced and diced. Mistakes happen here on Earth too. I've got absolutely no problem with 3698.9685 seconds in an hour. Its the computer's problem, really. Humans just won't notice. Like in coding, if there has to be uglyness, keep it confined.

I really can't see a time keeping system that doesn't have these issues, unless you stretch the second itself. Which again is in the realms of implementable. Its just that the kinds of errors that will occur will be rather more interesting.
« Last Edit: 03/31/2017 01:43 AM by Russel »

Offline Russel

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Re: Mars Timekeeping System
« Reply #164 on: 03/31/2017 01:22 AM »
Footnote. It occurs to me that decimal notated seconds can be applied as a sub unit for sols as well as it can for hours.

So 123:456 would mean 45600 seconds into sol 123.

The third digit would have a precision of 100 seconds. Useful for most purposes. The second digit would have a precision of 1000 seconds. Useful for larger blocks of time.

Again, the purist in me would like to do without both minutes and hours. Just use seconds and sols as the basic units. But I would not be unhappy with a 24 hour clock even if that means Earth hours and Martian hours are slightly different animals. Where would this matter in practice?

« Last Edit: 03/31/2017 01:41 AM by Russel »

Offline CuddlyRocket

Re: Mars Timekeeping System
« Reply #165 on: 03/31/2017 11:43 AM »
Quote
Abstract
The above most regular arrangement of months (corresponding to 12 bi-months) and a 7 day Martian week, also offer the possibility of conveniently adapting terrestrial month and day names to the calendar of Mars. The month names could be, e.g. Januarione, Januaryide; Februarione, Februaryide, etc., and those for days, e.g. Mondim, Tuesdim, etc.

For the names of the days I earlier suggested Monsol, Tuesol, Wedsol, Thursol, Frisol, Satsol and Sunsol, seeing as 'sol' seems to have taken hold for a Martian 'day'.

For the months, I'd suggest something like Janares, Febares, Marares, Aprares, Mayares, Junares, Julares, Augares, Septares, Octares, Novares and Decares (Ares being the Greek equivalent of Mars, etc).

Offline Russel

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Re: Mars Timekeeping System
« Reply #166 on: 04/01/2017 12:58 AM »
I'll just recap on part of that longer post above about Martian calendars.

There is a common assumption that Martian calendars must have months (and thus names for months). Now I'm not disputing the utility of subdivisions within a year. Nor does it particularly matter if there are months (or not).

My point was simply that before we have a calendar as such, there will be numbered sols. And whether or not there is a formal attempt (what authority?) to create a Martian calendar, Martians will inevitably refer to Earth days, Earth months and Earth events.

These will get mapped onto sol numbers and sol ranges. So my argument here is not about the ideal but about probable actual outcome. Martians will most probably refer to "June 22" and mean the sol that is agreed to represent the Earth day according to the Earth calendar. It will also tend to be the case that Martians will also refer to Earth months in their day to day discussions and this will again be referring to the range of sols that best map the Earth month.

Now leaving aside the inevitable Earth based framework, what happens if for instance Earth gets hit by the proverbial asteroid and there's no-one to write home to? What makes sense on Mars? This is where I feel that the tendency to simply repeat an Earth-like calendar makes no sense beyond familiarity. Ok, first Mars has its seasons. Then there is utility in having broader sub units to a year. But do they get called "months" and do they get names? I don't feel compelled to do this. To be honest I'd be perfectly happy to live on a planet where if having hundreds of sols per year is a bit clumsy then the tradition is to refer to the week number. And I also wouldn't mind if people referred to the "third week in summer", where summer is defined as a certain range of weeks.

I do love some of the interesting schemes for creating calendars btw. The question is why have a "calendar" as such, if calendar means having named months - especially if the motivation isn't about local utility but really about having something "earth-like".

Here's another thought. My birthday is in January. It means something because its the time of the year when its always hot (Australian summer) and its great to get to the beach. If I moved to Mars and Mars had a "January" or something that sounded like it, would it mean much to me? Not really. I'd still celebrate my birthday on whatever Sol happened to correspond to that day back on Earth. P.S I hope Mars has a nice heated wave pool.

Offline Dao Angkan

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Re: Mars Timekeeping System
« Reply #167 on: 04/01/2017 01:41 AM »
In other words, there's not much reason to not just keep using the same Earth calendar even on Mars.

Because Days != Sols, you slip against Earth's days by about one day every 5 weeks. So you can correct the Martian "week" back to Earth's day-of-the-week by skipping a day-of-the-week every fifth week. (And skipping the skipping roughly once per Earth year.)

I'd skip Monday.

That way, Martians can use normal named weekdays, use local time, and never be more than a half day away from UTC, as with any time-zone on Earth. So when it's Tuesday somewhere on Earth, it's always either Tuesday or nearly Tuesday on Mars. When it's March on Earth, it's March on Mars. When it's 2057 on Earth, it's 2057 on Mars.

[edit: Only the Martian time-of-day will be odd, but it must be odd, so again I'd just use decimal-Sols rather than trying to mutate Hours/Minutes/Seconds.]

Yes, this awkwardly tries to graft Earth's already convoluted Calendar onto Mars, but the advantage is that the time and date on Mars would essentially be the same as it is on Earth. (And on the moon, and on free-flying space-stations, and on ships in transit, and throughout the rest of the settled solar system.)

I was working out something similar, a "business calender" which would be useful for people dealing with businesses on Earth. A problem with financial markets will be the time delay, any investors on Mars (or on Earth if a Martian stock exchange ever materialises) would be at a disadvantage if important financial information gets released whilst markets are open. Thus it would be best practice to synchronise weekends and for companies to release their financial results and other important financial data during a period where Earth and Mars are both on weekends (especially companies with an interest in Mars). A 12 hour period once a week where this occurs could be enough, and that can be quite easily managed (even better in fact). We can also link Mars time to UTC.

24:40 Sols, after every 36 Sols the clocks go forwards 24:40 (a skip day). If it falls on a weekend, then Monday is a holiday (which is also the most common day for public holidays on Earth). Mars time will start the period at UTC+12:00, then slip back a 40 minute UTC time zone every sol, spending roughly the first 12 sols of the period in the Asian time zones, the second 12 sol period in the European time zones, and the final 12 sol period in the Americas time zones. Basically Mars is continuously dropping back through one of 37 40 minute UTC time zones (although it actually skips one every 36 sols/37 days). Ordering a Mars calender by those 37 time zones it's quite easy to work out the time difference between anywhere on Earth and Mars, plus you're aware that it generally slips by 40 minutes each day, and business hours with any particular time zone only coincide for roughly 2 working weeks each period.

24:40 sols does mean that you need to correct for this by putting the clocks forwards by an additional 40 minutes roughly every 95 sols on average. That could be done on the closest skip day (clocks go forwards 25:20 instead of 24:40) resulting in staying in the same 40 minute UTC time zone for two consecutive days, the pattern then continues.
« Last Edit: 04/01/2017 03:10 AM by Dao Angkan »

Offline Russel

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Re: Mars Timekeeping System
« Reply #168 on: 04/01/2017 05:50 AM »
In other words, there's not much reason to not just keep using the same Earth calendar even on Mars.

Because Days != Sols, you slip against Earth's days by about one day every 5 weeks. So you can correct the Martian "week" back to Earth's day-of-the-week by skipping a day-of-the-week every fifth week. (And skipping the skipping roughly once per Earth year.)

I'd skip Monday.

That way, Martians can use normal named weekdays, use local time, and never be more than a half day away from UTC, as with any time-zone on Earth. So when it's Tuesday somewhere on Earth, it's always either Tuesday or nearly Tuesday on Mars. When it's March on Earth, it's March on Mars. When it's 2057 on Earth, it's 2057 on Mars.

[edit: Only the Martian time-of-day will be odd, but it must be odd, so again I'd just use decimal-Sols rather than trying to mutate Hours/Minutes/Seconds.]

Yes, this awkwardly tries to graft Earth's already convoluted Calendar onto Mars, but the advantage is that the time and date on Mars would essentially be the same as it is on Earth. (And on the moon, and on free-flying space-stations, and on ships in transit, and throughout the rest of the settled solar system.)

A few things there. I can live with decimal fractions of sols, but for the following points:

1. It all depends on how much unfamiliarity you think will be accepted/adopted. It seems to me that if you did adopt an entirely unfamiliar system for time then people will simply program their timepiece to render the base time (decimal fractions of a sol) into some other representation. And I suspect that most likely they will attempt to render the time in the form of a clock with hours. Ok, that's part judgement call, and it all depends on what the "authority" is and how much say the authority has.

2. Even if you don't like hours, there's also the alternative, which is also "clean" in the same way. That means using decimal notated seconds into a given sol as stated above. So 123:456 means "45,600 seconds from the start of sol 123". At least this way a sufficiently precise clock will actually be ticking seconds. A clock that ticks fractions of a sol with 5 digits will be ticking away something a bit shorter than a second.

3. Despite the language used, a "mutated" hour is still an hour to most people. Where does it cause a problem? Its like yards and metres. yes, they are different but then those that use them interchangeably also know when the difference matters.

Regarding weekdays. For some it would be nice to keep days of week aligned with Earth. But this has the following issues.

1. We need to consider what having named days of the week is actually for. On Earth its generally been a tool of social organisation. Having a placeholder for things that happen "weekly". Whether that's to do with work, leisure or whatever. There's really no need for a 7 day week. It probably won't do any harm to have one. But it must be noted that if you were into social engineering for a colony one of the levers you have is the length of the week. I've suggested using regular weekday names and 7 day weeks because all things considered its not that harmful to have weeks and having numbered weeks within a year is sometimes useful.

2. To the extent that having regular weeks is useful, Having irregular ones can cause problems. Especially if you do on Mars like you do on Earth and try to schedule stuff on a weekly basis (garbage collection, anyone?)

3. Its nice to have the property that "its Tuesday" means "its also Tuesday back on earth". But since the martian day is longer, there's no avoiding "lost" Earth calendar days. Skipping a day in the Martian calendar also means that the original correlation is lost. Skip a Martian Monday and that particular Earth Monday gets "lost". So it kinda defeats the original intent.

Now if you don't attempt to align days of week, then you're no worse off. You still have the situation where a given Earth calendar day (day of week etc) can be mapped to a given Mars sol. As an added bonus, if you keep sol numbers and days of week permanently aligned then its possible to convert back from the sol number to what day of the week it is.

I do acknowledge that having a Martian day of the week with the same name as an Earth day of the week can cause confusion. You either have to accept this and also accept that where there is ambiguity most people are going to append the suffix "Martian" where needed. Or you reinvent the names so they're familiar but obviously different. Again, its the yards and metres situation. In practice, people adapt quickly to the ambiguity.


I know its a subtle point, but a lot of calendar problems vanish if you don't attempt to have a formal Martian calendar that tries to preserve alignments and you don't attempt to copy the Earth convention of having months (Yeah, ok, being soft on having days of the week makes me a little bit pregnant, but months are just way too problematic).

For practical purposes you simply have two problems. One is an Earth event. In this case you can agree to assign a given Martian sol to an Earth event (or a range of sols). The other is mapping of Earth calendar days. In this case you might apply the simple formula that says that the Earth calendar day is mapped to the Martian sol with the greatest overlap.

This has the property that on occasion two Earth calendar days will map to the same Mars sol. Since the Mars calendar doesn't have months or days of the month this causes less heartache. It will mean that if you do have days of the week as a formal part of the Martian calendar that two Earth days of the week will map to one Martian day of the week and this will happen every 5 weeks or so.

So to repeat. Earth events are mapped to Martian sols by agreement or convention. Earth calendar days are mapped by a hard formula. And by the same principle, Earth calendar months will map to ranges of Martian sols. This does not create formal Martian months. Its simply a convenience to know what month it is back on Earth and conversely which range of sols will be "the Earth month of January".

Again philosophically from the point of view of the Martian, there is no Earth-like calendar. Only sols and weeks. For purposes that involve reference to Earth you have a mapping. For purposes that involve Mars you then start to think of other ways to subdivide a year, if at all necessary.
« Last Edit: 04/01/2017 07:59 AM by Russel »

Offline Paul451

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Re: Mars Timekeeping System
« Reply #169 on: 04/01/2017 12:29 PM »
(although it actually skips one every 36 sols/37 days).

If they are using an Earth-synced calendar, then 36 sols to 37 days is an awkward match. That's why I preferred 34/35. Dropping one day every fifth week, repeatedly. By doing that, you end up losing two days a Martian-year, meaning you have to skip-the-skipday roughly once per Earth-year. IMO, it will be easier for people to keep track of one floating date per year than 10.

(Even better, work out a pattern like: skip the first Monday of every month, except June and December. Except December on any year divisible by either 10 or 25. Except...)

Such a synchronisation-pattern is awkward and convoluted, but the bonus is that the date is always the same as on Earth.

A problem with financial markets will be the time delay, any investors on Mars (or on Earth if a Martian stock exchange ever materialises) would be at a disadvantage if important financial information gets released whilst markets are open.[...] A 12 hour period once a week where this occurs could be enough,

A Mars investor will always be at a disadvantage on Earth markets, they will always need an Earthside representative to handle their trades. (The same true for Earthside investors in Martian stock exchanges.)

As for synchronised publication periods: This creates the risk that while the information is available but withheld on Mars, say, it can be leaked in other communications, giving some people up to a week advantage. I'm not talking about insider trading, but information which is fairly widely known informally in the small community on Mars, but withheld from Earthside investors. To control that, you would have to put all Earth/Mars communications on the same once-day-a-week release schedule.

Better to just release the info as it occurs.

Offline Dao Angkan

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Re: Mars Timekeeping System
« Reply #170 on: 04/01/2017 01:13 PM »
Example of Mars-Earth business calender;


Offline Paul451

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Re: Mars Timekeeping System
« Reply #171 on: 04/01/2017 06:39 PM »
I'm breaking this into a bunch of posts... Not sure if that helps or just annoys people more...


1. It all depends on how much unfamiliarity you think will be accepted/adopted. It seems to me that if you did adopt an entirely unfamiliar system for time then people will simply program their timepiece to render the base time (decimal fractions of a sol) into some other representation. And I suspect that most likely they will attempt to render the time in the form of a clock with hours. Ok, that's part judgement call, and it all depends on what the "authority" is and how much say the authority has.

If people render 0.nnnn into an alternative clock display, they'd just use an actual Earth clock, hh:mm:ss, 86,400 SI seconds. Either set to a specific timezone on Earth and allowed to drift against Mars time, or reset once a Sol (a-la KSR's Mars trilogy).

IMO, it's highly unlikely that people would unofficially adopt any of the elaborate proposals for a Mars "clock" that have been floated in the thread. Not 24 extra long Mars-hours of >60 minutes, or long Mars-minutes of >60 SI seconds, nor your hybrid hour/decimal-seconds system. It would just cause too many problems. (Especially when different people use different variations.) No-one would voluntarily choose such odd-ball systems.

[That said, someone earlier in the thread mentioned that some MSL scientists had watches/etc with a slightly slowed second, to stretch 24hrs out to a Mars sol. Obviously it wasn't used for measurements with an explicit or implied time component (power, velocity, force, etc), but just for ad hoc time-of-day ballparking. So that may be something you see on Mars.]

people will simply program their timepiece

Try it.

How many timepieces (including clocks built into appliances) do you own that you can program with a different time-keeping system?

You might download an app onto your smartphone, if such an app is available, but you aren't going to change the time function on any fixed device. That means if a decimal-Sol is adopted as the official time system on Mars, you will use it for a lot of tasks, which means you will get used to it.

(Alternatively, you'll use native Earth clocks, which will either drift 39+ minutes a day out of sync, be reset every Martian midnight, or will be modded to slow their time-chip by 2 and a bit percent.)

Offline Paul451

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Re: Mars Timekeeping System
« Reply #172 on: 04/01/2017 06:39 PM »
2. Even if you don't like hours, there's also the alternative, which is also "clean" in the same way.

"In the same way", meaning not at all.

It's the same problem with your other proposal (or KSR's 39 minute cocktail time, or the long-minute that has been suggested earlier in the thread.)

How do you track the length of time when it crosses the distorted unit? It's easy to say "let the computers handle it", but that's just avoiding the issue. Humans have to understand and work with this system. Humans have to work out how to fill in their time-sheets, or monitor a system/patient at fixed intervals, or just work out when "half an hour" from now is.

I do accounting for a living, often that's involved payroll processing. Vary few companies have fully-automated work tracking and none that I've worked for have even used punch-clocks. Generally workers have to manually log their start and finish times, or just total their hours each day and have their supervision sign off on it. In your proposal, how many hours did someone work between 8:2000 and 16:1000? If someone gets a 1500 second break, and takes it at 12:3000, when are they back on duty? No calculators, no spreadsheets, you're looking at your watch and trying to work it out while you are walking to the vending machine.

(This is also the problem with end-of-day partial units. If you have an extra 39-and-somit minutes pseudo-hour, or stop the clock as in the Mars Trilogy, then how does an ordinary human work out time across the mutilated unit?)

It's funny that you're bothered that my (and Dao's) suggested Earth-synchronised calendar means you skip one day every five weeks, but you don't mind every single hour of the day having a vastly weirder distortion.

3. Despite the language used, a "mutated" hour is still an hour to most people. Where does it cause a problem? Its like yards and metres.

No. It's like feet and feet. Or gallons and gallons. Ounces and ounces, miles and miles, etc.

The problem with the imperial system wasn't that they weren't in multiples of ten, it was that every region (sometimes a single city), and often different professions within a region, used slightly different size/length units for the same thing.

The US didn't have a standard "Foot" until the late 19th century (the Mendenhall Foot, aka US Survey Foot), different states/towns used different feet. And even that standardised US Survey Foot was slightly different from the English Foot, also used in Australia, Canada, etc. Both of which were different from the 1959 "International Foot" (which is defined in metres, but is different from the ISO "metric foot".) That's just the US and UK, there were also many dozens of different "foot" units used just across Europe. Germany alone had over a dozen, varying by up to a 25 percent.

Likewise the US and UK had different gallons and ounces. You said you were Australian (happy ironic-timing end-of-daylight-savings), if you're my age or older, you would know that even after Australia metricated, you still had to keep track of whether a "gallon" container was in pre-metric (UK-based) Australian gallons, or a recent import in US gallons, because they weren't the same gallons.

You will have two units called "hours" which are not the same, but also not different enough to be instantly obvious from context which one you are using. In your proposal, the units aren't even internally consistent.

But since you're so completely altering the meaning of Hour, why stick with a unit of 1/24th? Familiarity? Except that it's not familiar. Convenience? Except that it's not convenient.

[It's going to be bad enough with other units, given that we colloquially use mass units for weight on Earth. Which means a "kilogram" on Mars depends on what the person means, weight or mass. And there's no accepted alternative term for "year" that works for the Martian year. We use "Sol" for the Martian day in this thread, but honestly I'd expect people actually on Mars to switch back just saying "Day" colloquially and having to clarify whether they mean Earth or Mars. Deliberately adding that same confusion to hours, or months, or days of the week, is ridiculous.]

Again, its the yards and metres situation. In practice, people adapt quickly to the ambiguity.

Actually, in practice it's always caused problems, which is why there was an urge to standardise. Even the US went metric in its own clumsy backwards stupid way.

Offline Paul451

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Re: Mars Timekeeping System
« Reply #173 on: 04/01/2017 06:40 PM »
For some it would be nice to keep days of week aligned with Earth. But this has the following issues. [...]

Not really seeing any of your objections being specific to Earth-syncing. They describe the conversion problems that exist with any Mars timekeeping system. Any Martian time-keeping system, no matter how simple or complex, will still be cumbersome to converted back to Earth time. Any non-syncing Martian calendar will need to be converted to and from Earth dates, in a complex way. Even just counting Martian years means a complex conversion to Earth years, when changing back and forth.

Any attempt at a Martian calendar will be convoluted because the number of Sols per Martian year is not a whole integer, let alone an even multiple. (Unless you just use the basic Sol-count non-calendar.) It's the same reason that Earth's calendar is so convoluted. (Although the damn Romans didn't help.)

The only difference with an Earth-synchronising calendar is that months and years are the same as on Earth (not just the same system, but the same. June 2057 on Earth is June 2057 on Mars.) And even the day/date is never more than 1 day out, which happens with dates on opposite sides of the International Dateline anyway. (A live event in the US on Friday happens in Australia on Saturday.)

3. Its nice to have the property that "its Tuesday" means "its also Tuesday back on earth".

It's not about the named days, that's just a bonus. It about having the dates line up. Never further out of sync than places on Earth. It's not about "nice", it's about having a consistent dating scheme, potentially anywhere in the solar system, rather than trying to invent some convoluted Martian calendar that doesn't actually serve any purpose except remembering when the dust-storm season is.

Skipping a day in the Martian calendar also means that the original correlation is lost. Skip a Martian Monday and that particular Earth Monday gets "lost". So it kinda defeats the original intent.

Ten times per year, Mars effectively crosses west over the International Date Line. Other than that, Earth and Martian dates are synchronised every single day of the (Earth) year.

(And the skip is a whole day. Not 0.36990175...th of a day. One. If you need to convert across the skip, you subtract one day. Done.)

Offline Paul451

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Re: Mars Timekeeping System
« Reply #174 on: 04/01/2017 06:41 PM »
I know its a subtle point, but a lot of calendar problems vanish if you don't attempt to have a formal Martian calendar that tries to preserve alignments and you don't attempt to copy the Earth convention of having months

As I said before, I'm happy to just count Sols. People will, IMO, better adapt to remembering key times in three-digit numbers (or rounded off to nearest hundreds or fifties), than they will to some kind of convoluted Martian calender, where you have to first remember the Martian-formatted date and then remember what that date means.

However, if you are going to try to create Martian weeks/months, it will always be a convoluted system. My point was, if people keep insisting on having a convoluted system because "people use months therefore people must use months", then get something useful out of it, like synchronising with Earth dates.

I mean, even if you had an enforced Martian calendar that counted in Martian years, people are still going to think in terms of the Earth calendar for a long, long time. Possibly several generations. I am 46 years old. On Mars I would be 46 years old. I would not be 24 Mars-years-old, or 25, or whatever it works out at. I will not celebrate (or actively avoid thinking about) my birthday once per Martian year on the 15th day of Second-July (or whatever), it will be whatever Sols corresponds to my birthday on Earth.

Same which Christmas and Easter and other festival days that people care about, same as other anniversary days, including the length of time the colony has existed on Mars, or the length of your marriage.

It's not something you will have to force on people. They'll do it anyway.

Adopting skip-days just formalises the method of conversion.

So to repeat. Earth events are mapped to Martian sols by agreement or convention. Earth calendar days are mapped by a hard formula. And by the same principle, Earth calendar months will map to ranges of Martian sols. This does not create formal Martian months. Its simply a convenience to know what month it is back on Earth and conversely which range of sols will be "the Earth month of January".

How is that different to what I said?

Except I'd have the people on Mars actually using that Earth calendar for their own internal dating, instead of trying to awkwardly convert back and forth to some official Mars-year calendar.

Offline Russel

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Re: Mars Timekeeping System
« Reply #175 on: 04/02/2017 04:23 AM »
Paul. Just a quicky since I'm mobile.

The question is, why have an Earth-like calendar at all? Ie with months and days of the month? I can dig the need to to work with days snd events back on Earth, but why copy that formally into a Martian calendat?

I'll respond to the rest when I have s keyboard.

Offline A_M_Swallow

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Re: Mars Timekeeping System
« Reply #176 on: 04/02/2017 04:29 AM »
Paul. Just a quicky since I'm mobile.

The question is, why have an Earth-like calendar at all? Ie with months and days of the month? I can dig the need to to work with days snd events back on Earth, but why copy that formally into a Martian calendat?

I'll respond to the rest when I have s keyboard.

A week is needed because people need a regular rest day to allow their minds and bodies to recover. 10 days between rests was too long.

Offline Russel

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Re: Mars Timekeeping System
« Reply #177 on: 04/02/2017 10:30 AM »
Paul. Just a quicky since I'm mobile.

The question is, why have an Earth-like calendar at all? Ie with months and days of the month? I can dig the need to to work with days snd events back on Earth, but why copy that formally into a Martian calendat?

I'll respond to the rest when I have s keyboard.

A week is needed because people need a regular rest day to allow their minds and bodies to recover. 10 days between rests was too long.

I actually tend to agree about needing a weekly cycle. But its actually an interesting question as to whether it is better as 7 days, 5 days or 10 days. I think if you drilled into this issue you'd end up with a bunch of assumptions about the nature of work, convention and culture.

The reason I suggested a 7 day week is simply that its familiar, we already have names for the days and I think its relatively harmless in the sense that there may be an optimum number of days but 7 days isn't far off. I could be wrong of course.

Offline Paul451

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Re: Mars Timekeeping System
« Reply #178 on: 04/02/2017 10:54 AM »
The question is, why have an Earth-like calendar at all? Ie with months and days of the month?

I didn't say have an "Earth-like calendar", I suggested using just the actual (Earth) calendar on Mars and ignore the Martian year.

Prior to that, I've always pushed against creating an Earth like calendar for the Martian year. If you want to track the Martian year, you just count Sols. Nothing else makes sense.

Offline Russel

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Re: Mars Timekeeping System
« Reply #179 on: 04/02/2017 11:42 AM »
I'm breaking this into a bunch of posts... Not sure if that helps or just annoys people more...


1. It all depends on how much unfamiliarity you think will be accepted/adopted. It seems to me that if you did adopt an entirely unfamiliar system for time then people will simply program their timepiece to render the base time (decimal fractions of a sol) into some other representation. And I suspect that most likely they will attempt to render the time in the form of a clock with hours. Ok, that's part judgement call, and it all depends on what the "authority" is and how much say the authority has.

If people render 0.nnnn into an alternative clock display, they'd just use an actual Earth clock, hh:mm:ss, 86,400 SI seconds. Either set to a specific timezone on Earth and allowed to drift against Mars time, or reset once a Sol (a-la KSR's Mars trilogy).

IMO, it's highly unlikely that people would unofficially adopt any of the elaborate proposals for a Mars "clock" that have been floated in the thread. Not 24 extra long Mars-hours of >60 minutes, or long Mars-minutes of >60 SI seconds, nor your hybrid hour/decimal-seconds system. It would just cause too many problems. (Especially when different people use different variations.) No-one would voluntarily choose such odd-ball systems.

[That said, someone earlier in the thread mentioned that some MSL scientists had watches/etc with a slightly slowed second, to stretch 24hrs out to a Mars sol. Obviously it wasn't used for measurements with an explicit or implied time component (power, velocity, force, etc), but just for ad hoc time-of-day ballparking. So that may be something you see on Mars.]

people will simply program their timepiece

Try it.

How many timepieces (including clocks built into appliances) do you own that you can program with a different time-keeping system?

You might download an app onto your smartphone, if such an app is available, but you aren't going to change the time function on any fixed device. That means if a decimal-Sol is adopted as the official time system on Mars, you will use it for a lot of tasks, which means you will get used to it.

(Alternatively, you'll use native Earth clocks, which will either drift 39+ minutes a day out of sync, be reset every Martian midnight, or will be modded to slow their time-chip by 2 and a bit percent.)

Ok well first of all, I'd like to try to understand what you're preferred concept is, and the logic behind it. I think you're advocating a timekeeping system based on sols and then decimal fractions of sols. Or am I wrong here?

I'm not exactly clear as to what the argument in your first paragraph actually is. My point is that given an "official" timekeeping system that is in fact sols.fractions, people will look for more familiar/convenient methods and use those as a matter of practical day to day activity.

Indeed you're quite right (I think you're suggesting this) that they may just render sols.fraction into HH:MM:SS  with slightly stretched seconds.

Indeed, its possible that people will have three clocks. The "official" one (sols.fraction), a local time 24 hour clock (with stretched seconds) and also a clock based on some time zone on Earth.

So I take your point that a decimal notated seconds system is harder sell. I think it has its advantages over (sols.fractions) but you've caused me to come to terms with the fact that its even more likely that people will just use a familiar clock face showing local time, that just happens to stretch the second.

My original proposition to use decimal notated seconds alongside hours (HH:SS) was an attempt to not have "Martian seconds" whilst still trying to have a clock that is familiar and convenient to actually use. Well, you've probably changed my mind here. We're going to have "martian" seconds.

As for how many timepieces can be reprogrammed? Lots of stuff cannot be. Its hard coded with frequency references based on the SI second. If I really wanted to be difficult about this I'd also point out that I have the tools to rework basically anything electronic including replacing frequency references and mess with firmware, but hey, that's just me.

You might want to think twice about actual simple appliances created for Mars. For a start we're talking 20-30 years from now, at least. Secondly I can only imagine that the smartphone or its successor will be very much a part of life on Mars as well on Earth. And so will be display technology. I very much doubt that people on Mars won't have easy access to devices that can be used for multiple time systems. Whether its their "smartphone" or their toaster. Computing technology will be even more pervasive. So I've no problems in making the claim that technology will, quite definitely, be looking after all the boring detail.

Again, about sols.fractions I'm not suggesting its a bad idea. I'm simply saying that there is every chance that unless you have an authority that tells people they must actually use it, then people will resort to the familiar regardless. Even if they "mutilate" the second in the process.


Offline Russel

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Re: Mars Timekeeping System
« Reply #180 on: 04/02/2017 11:46 AM »
The question is, why have an Earth-like calendar at all? Ie with months and days of the month?

I didn't say have an "Earth-like calendar", I suggested using just the actual (Earth) calendar on Mars and ignore the Martian year.

Prior to that, I've always pushed against creating an Earth like calendar for the Martian year. If you want to track the Martian year, you just count Sols. Nothing else makes sense.

Ok well at the risk of getting further out of synch, let me ask.

Are you proposing months and days of months to be formal elements in an official Martian calendar?

Or are you actually proposing what amounts to a quite separate lookup table? A calendar structured around Martian sols with the corresponding Earth calendar entry marked for each sol?

I'm in favour of the latter.
« Last Edit: 04/02/2017 11:50 AM by Russel »

Offline Paul451

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Re: Mars Timekeeping System
« Reply #181 on: 04/02/2017 12:41 PM »
The question is, why have an Earth-like calendar at all? Ie with months and days of the month?
I didn't say have an "Earth-like calendar", I suggested using just the actual (Earth) calendar on Mars and ignore the Martian year.
Are you proposing months and days of months to be formal elements in an official Martian calendar?

No.

Or are you actually proposing what amounts to a quite separate lookup table? A calendar structured around Martian sols with the corresponding Earth calendar entry marked for each sol?

No, and also no.

I'm saying you buy a calendar on Earth before you travel to Mars and that's the calendar you use on Mars.

But if you mark off days/dates on the calendar one-per-Sol then after about 36 Sols, you'll be a full day out of sync with the date on Earth. So you mark off two days/dates in order to get back in sync with Earth.

Formally then, I suggest getting everyone on Mars to skip the same specific days/dates on their respective calendars, in order to save confusion amongst themselves.

Dao Angkan suggests the same basic thing (at least for his "Business calendar"). We differ in when to skip over a day/date. Dao wants it to be when it's actually necessary, at 36 Sols, which is the 37th day on Earth. By skipping over the 37th day on the calendar, the next day is the 38th day on both planets.

Me, I think people would prefer a system that has a more convoluted pattern, but is easier for humans to remember. I suggested a specific day every fifth week, requiring a correction of roughly one day per (Earth) year. Then I suggested another pattern, such as the first Monday of every month, except in June and December, with further single-day corrections at memorable years (divisible by 10 and/or 25, etc). (I haven't bothered to fully map the latter pattern, so I'm not sure what the "further" corrections actually need to be.)

In Summary:

There is no such thing as a "Mars Calendar". There is only the Earth calendar.

But: The Sol is roughly 37/36ths longer than an Earth day.

Therefore in order to use a normal, unaltered Earth calendar on Mars, and mark off Sols as if they were days, and stay in sync with someone using the same calendar on Earth, you need to occasionally skip over a date. Annoying, but the reward for doing so means that you are never more that 12 hours out of sync with UTC-Earth.
« Last Edit: 04/02/2017 02:57 PM by Paul451 »

Offline Paul451

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Re: Mars Timekeeping System
« Reply #182 on: 04/02/2017 02:54 PM »
I think you're advocating a timekeeping system based on sols and then decimal fractions of sols.

Yes.

I'm not exactly clear as to what the argument in your first paragraph actually is. My point is that given an "official" timekeeping system that is in fact sols.fractions, people will look for more familiar/convenient methods and use those as a matter of practical day to day activity.

I don't think it'll be that common. Using Australian metrication as an example, people almost universally use metric and typically only use Imperial units in colloquialisms and approximate measure ("move it a couple of feet to the left"). And it didn't take long for people to get a feel for what a kilogram of sugar was, or a litre of milk, or a hundred km/h.

(Come to think of it, other than feet and inches and a few figures of speech involving miles, the others have faded almost completely out of use. I can't remember the last time I heard someone in Australia refer to "half a gallon" or "a couple of pounds", and certainly no-one born post-metrication.)

Indeed, its possible that people will have three clocks. The "official" one (sols.fraction), a local time 24 hour clock (with stretched seconds) and also a clock based on some time zone on Earth.

I really can't see that combination happening.

If there's an official time-keeping system, people will use that most of the time simply by necessity and quickly adapt to it. After a generation, young people will need a special app to understand Earth time because it will seem weird and counter-intuitive.

OTOH, if there's no official system, people might start using a stretched-second 24hr clock. Simply because it's relatively easy to modify time-keeping circuits to slow them by 3%, and initially every single time-keeping device will come from Earth. That might end up becoming official, simply because it's become too engrained by the time anyone has enough authority to make something official.

But I can't see both an official decimal-sol system being adopted and a common use of slow-second devices. If the latter hasn't become cultural-habit by the time the former is declared, then it won't become common. If the latter has become common, there'll be no sense of need to adopt the former.

Personally I thought scientists/engineers would have been the last people to mess with the length of the second, so this surprised me. But if scientists at JPL are doing it, then there's obviously not a huge resistance to it. I dislike it, but I can see it just happening.

No other proposed time system, including your suggestion, makes any sense. (IMO) They are terrible for official timekeeping, and they wouldn't arise naturally because they are terrible for people.

[People will need to know the time on Earth whenever they have a reason, obviously, but that has nothing to do with the local time-keeping system. However, I know plenty of migrants, and I don't know a single one who has a clock in their home set to that time-zone. It's more a business thing. So I can't see that becoming common on Mars.]

I've no problems in making the claim that technology will, quite definitely, be looking after all the boring detail.

A system has to be usable by humans. People need to be able to work out in their head what current_time+time_interval equals. I'm posting this at just after of 12:20. Thirty minutes ago, it was just after 11:50. A Mars clock needs to be that usable.

Your 3,698.968506125 seconds in a "Mars hour" is not usable. (Unless we're talking post-Singularity augmentation directly in the brain.)

Offline Dao Angkan

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Re: Mars Timekeeping System
« Reply #183 on: 04/02/2017 10:21 PM »
Example of Mars-Earth business calender;

There's a pretty major flaw in this calender. UTC-12:00 is essentially the same time as UTC+12:00, so really only 36 x 40 minute time zones. Still, that might be useful for the ~95 sol +40 minutes period. I'll rework it and also do a couple of variations such as the 5 week interval suggested by Paul. Also, if you do it at a higher frequency than 36 sols/ 37 days then maybe it would be more intuitive to just skip the last day of the month (which we already do with February every 3 out of 4 years ... although admittedly we don't actually skip the day of the week).

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