Author Topic: Mars Timekeeping System  (Read 57907 times)

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.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline mikelepage

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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.

Offline 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.

Offline 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 »

Online 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.
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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 »

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