Time and Calenders on Mars, a proposal
--------------------------------------------------------
In an article of the jan/feb 2004 issue of the planetary report (page 10)
there was a story about time and calenders on mars. It tickled me to get
a sheet of paper and start calculating. In fact it needed more papers and
this is the (scrutinized) result.

There are 3 important constants in the Martian Time table

1) 1 mars second = 1 earth second (preserve the SI units)
2) 1 Sol = 24h39m35.2s (earth)
3) 1 mars year = 668.6 sol

[the latter 2 numbers are from the article!]


Years and leap years.
------------------------------
I call 1 mars year a Mear (pronounce Mir).
1 Mear has no round number of sol's so we should introduce leapsols. In
fact we need 3 leapsols every 5 years. The formula for this is quite easy:

if ((mear %5) %2) == 0 ) => leapmear => add a leapsol.

Leapsols are added on the day just opposite to the martian new year and
will be an offical holiday (just as new year's day is).

So there exist a 5 Mear period, a quintennium, which repeats.
The number of sol in a Quintennium is 3 x 669 + 2 x 668 == 3343 sol.


Seasons and months
------------------------------
1 Mear has 4 seasons called Ice, Melt, Gas and Freeze which refer to the
state of the CarbonDioxide caps on the planet.
Every season has 668/4 = 167 sol.

1 mear has 23 months of 29 days + 1 new years day (holiday)
The months are just the first 23 letters of the alphabet to remember
them easily. I did not look for good names but at least I think the J
should be Jouri (in remembrance of Jouri Gagarin). In fact it doesn't matter
how people call the months as long as they use the correct first character.


Dividing the sol.
-----------------
How is a sol divided? Recall that 1 Sol = 24h39m35.2s.
First deal with the .2 seconds => every 5 sols a sol has a leap second.
that gives us 1 sol = 24 x3600 + 39 x 60 + 35 = 88775 seconds.
88775 = 5 x 5 x 53 x 67. So it make sense to divide a sol in 25 Slices
of 53 x 67 = 3551 seconds. Almost an earth hour just a small 1.4%
difference.

This leads us to the question should we have 67 mars minutes of 53
seconds or 53 mars minutes of 67 seconds. I have no real argument for
eather but I like 67 minutes in an hour as I often need a few more minutes to get
things done, now I can have them Note that this martian time framework would
imply 25 timezones on Mars, but that is no problem.


How about the martian week?
----------------------------
As the sol and the day do not sync it is unwise to synchronize the
martian week and the earth week. So how long should a meek (martian
week) take? 7 days seems to make sense as we humans are used to it. However as the
days do not sync earth days a monday on mars will seldom be a monday on
earth (chance 1 in 7). For Martians the 5 day week is better, It matches
Deimos a bit but most important we could have every leapsecond in the
weekend (which unfortunately is only 1 day). Again I did not spend time to name
the days of the week (thumb, index, middel, ring and pink?).

Last but not least a 'phobe' as mentioned in the article is approx, half
a sol and will be used for informal purposes only, like: "I stayed in
the pub for half a phobe".


To be done.
-----------
What still has to be done is to build an algorithm to convert earth
datetime to martian datetime. For this we should have a reference date.
A good one to remember is jan 1st 2000 is new years day Mear 0 on Mars.


In conclusion
-------------
The martian time system is filled with primes:

- A quintenium has 3343 sol (3343 is prime.
- 3 mears out of 5 are leapmear. (3 and 5 is prime)
- Every season has 167 sols (167 is prime)
(In a leapmear one season is one sol longer)
- 1 Sol has 25 slices
(OK 25 is not a prime but at least it is the square of a prime)
- 1 maur has 67 manutes (martian minutes) (67 is prime)
- 1 Manute has 53 seconds. (53 is prime)
- every 5 sols there is a sol with a leap second. (5 is prime)
- The number of months is 23 (23 is prime)
- The number of sol in a month is 29 (29 is prime)
- 1 meek has 5 sols. (5 is prime)

Although the latter three are by choice, the children on Mars better be good in math!

Best regards,
Rob Tillaart
ps,
I cannot wait to buy a martian watch, or one with both mars and earth time

[note 28-01-2004 I noted the original text was double; so I removed one ]

:blink: :blink: very interesting calculations and proposal! waht does this do to my birthday!!

Do you have a link to that site that first did the calculations?

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International Baccalaureate Physics teacher
Spectroradiometry Instrumentation Major
Admin: Pacific Science and Art

Okay, I'm gonna need more coffee before I can properly understand all the math I like the thinking though

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Made the calculations myself, maybe others have some similar framework developed. But I don't know if there exist any formal timeframe for Mars. I wrote this proposal as a reaction on an article of a Professor of Washington Uni. Sent him a copy but got no reaction from him yet.

>> waht does this do to my birthday!!
Your Earth (I assume) birthday will be a different Mars day every time if you celibrate it once an earth year. If you were born on Mars you would have less
birthday parties (and less presents .

A friend who proofreaded the proposal came up with the question " and how about the other planets and moons?". I have no clue except that moons should follow the mother planet if that has a timeframe.

For liquid/gas planets like Jupiter it is very difficult to imagine a timeframe as every band has different orbit speed. For Jupiter the red spot could be used as reference. Different speeds give trouble with time zones. On earth we have the continental drifts but these are so slow that it will take a while before some country moves in a new timezone.

Rob Tillaart

Brilliant stuff!! Let us know of the outcome of your research, one planet that would interest me is a time frame model for mercury...

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Damien,
International Baccalaureate Physics teacher
Spectroradiometry Instrumentation Major
Admin: Pacific Science and Art

Only did some math for mars. I recall there are relativistic effects in the mercury orbit so the timeframe will depend on the place of the observer.
But I will give it a try, at least it will produce a story to shoot at and get the discussion started

Some Mercury facts:
[http://www.nasm.edu/ceps/rpif/mercury/rpifmerc.html]
(I will use these numbers)


other planets
[http://www.nasm.si.edu/research/ceps/rpif/rpif.cfm]

Rob tillaart

[/b][/quote]

These are my thoughts about the Mercury Timeframe

Regarding a Mercury TimeFrame.
--------------------------------------

First the hard data:
1: Mercury has no tilt.
2: Rotation around sun : 0.24 EYear = 87.66 Eday. (E=Earth)
3: Rotation around Axis: 1408 Ehours = 58.66 Eday
(source: www.nasm.edu/ceps/rpif/mercury/rpifmerc.html)

The first observation is that no tilt implies that there are no seasons. No seasons
means that people living on the planet do not (explicit) experience a year go by.
Only if they look at the night stars they might do so.

Second observation is that a MercDay is very very long in terms of Eday's, too long to get used to. Next the ratio between a MercYear and a MercDay = 0.6691.
[Note ArcSin(0.6691) = 42, see Hitchhikers guide to the galaxy ]

The effect of the long day is a very hot dayside ~700Kelvin and a cool nightside
of ~100 Kelvin. These temperatures imply that a human colony can only survive in
the twilight zone. The radius of Mercury is 2439 km => the equator = 15324 km.
At the equator the twilight moves at 15324km/1408 hours = 10.88 km/hour. This is more than 2 times as fast a human could walk. It will be very difficult to have a
human settlement moving constantly at this speed. However it would be good for
exploration, and in the early days humans were moving all the time too, so nothing new. Another option is to dig in the crust for 58 days.
So the only real suitable places for a human colony are the north and south poles
of Mercury. At a lattitude alpha the incoming sunlight is COS alpha times as strong as on the equator.
alpha = 89 degree (radius around pole = 15324/260 = 42 km) => sunlight = 2% of equator
alpha = 89.9 degree (radius = 4.2 km) => sunlight = 0.2% of equator.
So we can savely assume that it will not be that hot on the poles, but if you
stick up a solar panel (right angle) it will be flooded with sunlight, so plenty of energy if you want to. But staying at the poles would imply that someone on Mercurybase 1 can walk from dayside to nightside in a few Ehours or less. Practical speaking they live in the twilight constantly.

Conclusion
-------------
What does this mean for a day time framework for mercury? The planet itself does not give any usable timeframe as no seasons exist and the MercDay is way too long to get used to. Furthermore a human settlement need to stay in the twilight to have a controllable climate for a longer time. So there is no real day rythm experienced either. So for mercury I would propose to just use the Earth timeframe.

regards,
rob tillaart
PS,
Venus is not colonizable with current earth technology so let us use Earth timeframe for Venus too.

Did some searches on the net:

Mars24, a mars time calculator and some references to real math about time on Mars. See http://www.giss.nasa.gov/tools/mars24

I'm gonna send my story to them !

regards,
rob

It's an interesting topic. We think making international phone calls causes confusion with regard to time zones... wait until until there are humans on Mars!! Obviously phone calls to Mars would be impractical given the length of time light/radio signals take to reach there.

I think the reason this is so confusing is not because of the maths involved, but because we are simply so used to our date system. It's like counting numbers in hexidecimal. It's just as logical, but we're simply not used to it.

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