For better comparison to traditional climate diagrams, the starting point of this calendar is set to the 1st sol after the northern winter solstice (Ls 270, “January”) (also close to perihelion at 251 Ls). (Not as in Ls=0-starting calendars which start the Mars Year in “April”, like the [1], or [here]).
Also, Ls-based calendars obscure some natural phenomena (real length of summer/winter in northern/southern hemisphere).
The Ls=0 (spring) starting calendar is close to the one used by ancient Romans, where winter did not count since there was no main activity at the fields. Some Mars calendars like the CMEX Mars Calendar use variable-sol (40-72) -long months depending on the actual solar distance.
Comments. For practical purpose (like “monthly” measurements)
I used equal-sols months. Variable-length time units also go back to antiquity
when the length of the hours of a day depended on the length of the period
from Sunrise to Sunset; the total time was then divided. For practical
purposes I keep each time unit (sol, week [not used here] month, year)
equal length (as much as possible).
We kept traditional names of days/months, because these names are stronger
than civilizations: although it may be a proble not to mix them with Earth
Dates. We also kept AD years since there is no accepted first year for
Mars (may be only after human landing). The first human missions will probably
not use such calendrat: they will count sols from the arrival/to the departure.
Jan 1 is always monday, so the last days of the year will have a jump in
the traditional neverending row of names of days.
Here is an example of the use of calendar for 2007-8-9.
Main points of the year used for creating the diagrams
*1st sol of the Year (1999/12/25) **1st sol of the next Year (2001/11/12)
Ls Orbit (Vanilla) Orbit ("real") Spacecraft Clock
Description
269.5 3558
5241
~630529096 *
270 11961
13644 ~689871962
**
Main data of the “12×56/270” calendar used
A B sol C Ls D clock E Ls
F sol Comment
1 1 269.5 630529096 34.5
56 Ls 269,5 =?sol 1 =?Northern Winter Solstice
2 57 305.5 635496738 31.5
56
3 113 337.5 641171890 28.5
56 Ls 0 =?sol 153 =?N.?Spring Equinox
4 169 7.5 645758026 26
56
5 225 34.0 650213502 25.5
56
6 281 60.0 655689924 24.5
56 Ls 71 = sol 305 aphelion (249 m km)
7 337 85.0 660194188 25.5
56 Ls 90 = sol 347 =?N.?Summer Solstice
8 393 111.0 666916360 26.5
56
9 449 138.0 670405188 29.5
56
10 505 168.0 676122612 32
56 Ls 180 = sol 525 =?N. Autumn Equinox
11 561 200.5 680496118 35
56
12 617 236.0 685294644 33
52/53 Ls 251 = sol 639 perihelion (205 m km)
– 1 269.5 689871962
(668+1 sol)
Key
A: Month number;
B: 1st sol of the month (sol of the year)
C: Corresponding Ls (approx.);
D: Corresponding MGS Spacecraft Clock No. for 1999-2001 ;
E: Length in Ls unit;
F: Length in sols.
References:
[1] Clancy et al., Journal of Geophys. Res 105, p 9553, 2000