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A time system useful on Mars needs additional consideration; considerations we haven't given it yet. It requires more thinking than just time zones. The various

A time system useful on Mars needs additional consideration; considerations we haven't given it yet. It requires more thinking than just time zones. The various things we've sent to Mars haven't had any need for a colloquially time; they're computers, they just know that 21,872 seconds or whatever into the day is that far into an 87,755 second day and that's good enough to calculate shadow angles and expected solar panel efficiency from. If we were to build a colony on Mars with normal people doing normal everyday things, we need something more than that. The first question we want to ask ourselves is, do we want to keep the SI defined second? If we don't care, then we have free reign to do whatever we want. We can define a Mars second to be 1/86,400th of a Mars day, and keep the 24 hour, 60 minute, 60 second time system we use on Earth. Or we switch to a metric time system, with a 10 hour day, 100 minute hours, 100 second minutes. Or a 1 day long day, and deci, ceni, milli, micro days. Or whatever. If we want to keep SI compatibility, we need to keep the second. The Martian solar day is 87,755.224 seconds long. 87,755 factors into 5^2 * 53 * 67. So we can do 25 hours per day, 53 minutes per hour, 67 seconds per minute to give an 87,755 second day. Unfortunately there would need to be a leap second once every 4-5 days. Then there's the question of the calendar. Perhaps fortunately, this gives us the opportunity to restart from scratch, because the calendar we use is such a goddamned clusterfuck, even worse than our time system. Unfortunately, the number of days in a Martian year (668 and change) does not lend itself to a clean division into tidy periods. You could have 23 months of 29 days each, with each month having 4 7 day weeks plus one holiday. This will give you a 667 day year. Add another annual holiday at the beginning of the year, plus an optional leap-holiday in the middle of the year. Or you could split it up into 37 months of 3 weeks, each with 6 days. This gives you a 666 day year, so sprinkle in 2-3 bonus holidays per year. There are a lot of considerations. It needs to be given more thought. Hopefully more thought than we've given to Earth's timekeeping systems.

kryptiskt 6y ago
It's not a future problem, JPL personnel already work after Mars time: https://www.businessinsider.com/nasa-perseverance-team-mars-time-shifts-days-40-minutes-2021-2?r=US&IR=T https://www.businessinsider.com/nasa-perseverance-team-mars-...
kibwen 6y ago
Days, months, and years based on the cycles of the planet make sense on Earth, but not as much on Mars. Almost all Martian settlers will be living underground, and even aboveground the light at mid-day is extremely dim. You can set the day to whatever length you want, regardless of the Martian sol, and nobody will notice. Likewise, months and years on Earth are for tracking agricultural seasons, but nobody will be growing crops on the Martian surface. Set the year to whatever you want, with or without months, and no civilians will notice.
- floxy 6y ago
  >even above ground the light at mid-day is extremely dim. Direct normal insolation on Mars seems to be in the 590 W/m^2 range. https://duckduckgo.com/?q=590+W+insolation+mars&t=ffab&ia=web https://duckduckgo.com/?q=590+W+insolation+mars&t=ffab&ia=we... That's brighter than an average winter day in Seattle. http://www.weatherjon.org/meteo/pages/station/climate.php?var=S http://www.weatherjon.org/meteo/pages/station/climate.php?va... (click on "Month graphs", and then "Maximum".
  - kibwen 6y ago
    I was about to argue that that seems pretty anemic for a best-case scenario, but it occurs to me that the lack of a substantial atmosphere probably means you do at least avoid any reduction in light as the sol goes on; Martian sunrise is therefore probably brighter than Earth sunrise. Even still, being able to see the Martian sky means being exposed to radiation for which no intervening atmosphere or magnetosphere exists to protect you. I don't think this changes much about a Martian settler's unlikeliness to prefer to set their clocks according to solar time.
PeterisP 6y ago
For a person living on Mars it makes sense to align the time to Martian solar day iff their daily life is linked to outdoors activities in sun. However, if they are expected to stay indoors or even underground facilities (which IMHO is very, very likely at least for the first decades for various reasons) then the outdoors day is simply irrelevant, and it makes all sense to coordinate with Earth time for all your activities and just look up local solar time only when you need to schedule activity outside the base in the "wilderness" - where you're anyway going to spend just some hours, not a whle day/night cycle.
- zokier 6y ago
  If we are to send people to Mars then presumably we want some interaction with the surface. Otherwise we might as well send those people to underground bunkers on Earth.
  - kibwen 6y ago
    You will find no shortage of volunteers for Martian colonists, but understand that for anyone who just wants to be alive somewhere, there's an endless quantity of undesirable places on Earth in which to live that are all still veritable paradises compared to literally everywhere on Mars. About the only practical benefit of a Martian colony is to serve as a last-ditch backup of human civilization in the event of an asteroid strike. Mars won't be a powerhouse of industry, commerce, or culture; at best there will be some modest scientific output. It's a tomb world. Give humanity a few millennia to build a Dyson sphere around the sun and maybe then you could start reasonably terraforming Mars into somewhere intrinsically nice to live, over the course of a few additional tens of millennia.
    - ncallaway 6y ago
      I think there are reasonable martian terraforming timelines that take a couple hundred years. I don't think you need a dyson sphere level of energy output, or even a single millennium to terraform mars to be human habitable. It's a big project, to be sure, but if we were dedicated to it I think we could accomplish it in <1,000 years.
skissane 6y ago
> The first question we want to ask ourselves is, do we want to keep the SI defined second? I think absolutely yes. Any Mars colony is going to import a lot of equipment and technology from Earth. All of that is going to assume the SI second. Not just for measuring time, but also as part of the definition of derived units such as newtons. Martian colonists will have no practical choice but to use the SI second since all their Earth-manufactured equipment is going to assume it. Plus, if they tried to introduce a distinct Martian second, soon they'd have a mix of SI units (based on the SI second) and slightly different Martian units (based on the Martian second), and that would produce Mars Climate Orbiter style disasters. > Perhaps fortunately, this gives us the opportunity to restart from scratch People won't. People will want to use the Earth calendar because they are keeping in sync with Earth news and Earth culture. Maybe after a few centuries, Mars will feel sufficiently independent from Earth, that it might want to introduce a new calendar. However, by then Martians will be thoroughly used to the Earth calendar, it will be a centuries-old part of their Martian culture heritage, and they probably won't want to change it.
- elihu 6y ago
  I agree that changing the definition of seconds would cause all kinds of problems. However, having local time and a local calendar that are synchronized with when the sun comes up and the seasons I think makes a lot of sense, and it won't take centuries to implement. It'll probably happen as soon as people arrive on Mars. I like Kim Stanley Robinson's approach, as described in the Mars trilogy. They use standard seconds, but at 12:00 midnight, the clocks just stop for about 39 minutes. (Computers just use seconds-since-the-epoch or something and are unaffected.) Martian colonies will still care about Earth calendars, but only to the extent that they have to deal with Earth. Kind of like dealing with a different timezone on Earth. https://www.kimstanleyrobinson.info/content/martian-calendar https://www.kimstanleyrobinson.info/content/martian-calendar
  - skissane 6y ago
    > However, having local time and a local calendar that are synchronized with when the sun comes up and the seasons I think makes a lot of sense How important are the seasons going to be for people who have to spend the vast majority of their time indoors due to the lack of a breathable atmosphere – and possibly even underground for protection against radiation? Maybe one day Mars will be terraformed and given a breathable atmosphere, and maybe even some kind of artificial magnetosphere can be created to protect against radiation. But that is going to take many centuries. The fact is that modern societies don't really need a calendar synchronised to the seasons. Most jobs nowadays the seasons are not very important. This is especially true in parts of the world where the difference in weather between the seasons is less marked (like where I live, here it never snows in winter). Fields such as agriculture where seasons are important can always keep track of the seasons independently from the calendar, or using a special purpose agricultural calendar. In fact, that's what is traditionally done in much of the Islamic world – the Islamic calendar was used for most purposes, which is out of sync with the seasons. Those jobs for which seasons were important, such as farmers, also used a separate solar calendar. It was only in the 20th century that the need to participate in the global economy created pressure to use the Gregorian calendar instead. > I like Kim Stanley Robinson's approach, as described in the Mars trilogy. They use standard seconds, but at 12:00 midnight, the clocks just stop for about 39 minutes I don't know why you'd do that. On earth, clocks run from 00:00:00 to 23:59:59 each day. On Mars, you'd just make them run to 24:39:34 instead. That way you can actually get precise times for events that occur in those extra 39 minutes and 35 seconds that happen each day. (Also, I'd hope people on Mars would be using 24 hour time–I'm one of those people who changes all their clocks to 24 hour time on Earth) > Martian colonies will still care about Earth calendars, but only to the extent that they have to deal with Earth For the first few decades at the very least, Martian colonies will be dealing with Earth an awful lot. A lot of goods will have to be imported from Earth. There will be a lot of focus on what they can locally manufacture on Mars, but they'll start with basic stuff like foodstuffs and simpler manufactured goods, and it will be a long time before Mars has leading-edge semiconductor fabs or a lot of other stuff like that. There will also be continual immigration from Earth, and also people returning to Earth (whether temporarily or permanently). That's going to psychologically link them with Earth. Martians are also going to consume a huge amount of cultural imports from Earth. You think on Mars they won't have Netflix, YouTube, etc? They'll replicate the content library into a Mars-based CDN and people will be watching it on Mars. It is going to take a long time before natively produced Martian media/entertainment content becomes more popular than the Earth-imported stuff. And I think that's going to tie Martians to Earth at least as much as trade ties and movement of people back and forth will. Martian colonies will undoubtedly develop some unique cultural aspects, but a huge amount of their culture is just going to be Earth imports.

kryptiskt 6y ago

It's not a future problem, JPL personnel already work after Mars time: https://www.businessinsider.com/nasa-perseverance-team-mars-time-shifts-days-40-minutes-2021-2?r=US&IR=T https://www.businessinsider.com/nasa-perseverance-team-mars-...

kibwen 6y ago

Days, months, and years based on the cycles of the planet make sense on Earth, but not as much on Mars. Almost all Martian settlers will be living underground, and even aboveground the light at mid-day is extremely dim. You can set the day to whatever length you want, regardless of the Martian sol, and nobody will notice. Likewise, months and years on Earth are for tracking agricultural seasons, but nobody will be growing crops on the Martian surface. Set the year to whatever you want, with or without months, and no civilians will notice.

floxy 6y ago
>even above ground the light at mid-day is extremely dim. Direct normal insolation on Mars seems to be in the 590 W/m^2 range. https://duckduckgo.com/?q=590+W+insolation+mars&t=ffab&ia=web https://duckduckgo.com/?q=590+W+insolation+mars&t=ffab&ia=we... That's brighter than an average winter day in Seattle. http://www.weatherjon.org/meteo/pages/station/climate.php?var=S http://www.weatherjon.org/meteo/pages/station/climate.php?va... (click on "Month graphs", and then "Maximum".
- kibwen 6y ago
  I was about to argue that that seems pretty anemic for a best-case scenario, but it occurs to me that the lack of a substantial atmosphere probably means you do at least avoid any reduction in light as the sol goes on; Martian sunrise is therefore probably brighter than Earth sunrise. Even still, being able to see the Martian sky means being exposed to radiation for which no intervening atmosphere or magnetosphere exists to protect you. I don't think this changes much about a Martian settler's unlikeliness to prefer to set their clocks according to solar time.

PeterisP 6y ago

For a person living on Mars it makes sense to align the time to Martian solar day iff their daily life is linked to outdoors activities in sun. However, if they are expected to stay indoors or even underground facilities (which IMHO is very, very likely at least for the first decades for various reasons) then the outdoors day is simply irrelevant, and it makes all sense to coordinate with Earth time for all your activities and just look up local solar time only when you need to schedule activity outside the base in the "wilderness" - where you're anyway going to spend just some hours, not a whle day/night cycle.

zokier 6y ago
If we are to send people to Mars then presumably we want some interaction with the surface. Otherwise we might as well send those people to underground bunkers on Earth.
- kibwen 6y ago
  You will find no shortage of volunteers for Martian colonists, but understand that for anyone who just wants to be alive somewhere, there's an endless quantity of undesirable places on Earth in which to live that are all still veritable paradises compared to literally everywhere on Mars. About the only practical benefit of a Martian colony is to serve as a last-ditch backup of human civilization in the event of an asteroid strike. Mars won't be a powerhouse of industry, commerce, or culture; at best there will be some modest scientific output. It's a tomb world. Give humanity a few millennia to build a Dyson sphere around the sun and maybe then you could start reasonably terraforming Mars into somewhere intrinsically nice to live, over the course of a few additional tens of millennia.
  - ncallaway 6y ago
    I think there are reasonable martian terraforming timelines that take a couple hundred years. I don't think you need a dyson sphere level of energy output, or even a single millennium to terraform mars to be human habitable. It's a big project, to be sure, but if we were dedicated to it I think we could accomplish it in <1,000 years.

skissane 6y ago

> The first question we want to ask ourselves is, do we want to keep the SI defined second? I think absolutely yes. Any Mars colony is going to import a lot of equipment and technology from Earth. All of that is going to assume the SI second. Not just for measuring time, but also as part of the definition of derived units such as newtons. Martian colonists will have no practical choice but to use the SI second since all their Earth-manufactured equipment is going to assume it. Plus, if they tried to introduce a distinct Martian second, soon they'd have a mix of SI units (based on the SI second) and slightly different Martian units (based on the Martian second), and that would produce Mars Climate Orbiter style disasters. > Perhaps fortunately, this gives us the opportunity to restart from scratch People won't. People will want to use the Earth calendar because they are keeping in sync with Earth news and Earth culture. Maybe after a few centuries, Mars will feel sufficiently independent from Earth, that it might want to introduce a new calendar. However, by then Martians will be thoroughly used to the Earth calendar, it will be a centuries-old part of their Martian culture heritage, and they probably won't want to change it.

elihu 6y ago
I agree that changing the definition of seconds would cause all kinds of problems. However, having local time and a local calendar that are synchronized with when the sun comes up and the seasons I think makes a lot of sense, and it won't take centuries to implement. It'll probably happen as soon as people arrive on Mars. I like Kim Stanley Robinson's approach, as described in the Mars trilogy. They use standard seconds, but at 12:00 midnight, the clocks just stop for about 39 minutes. (Computers just use seconds-since-the-epoch or something and are unaffected.) Martian colonies will still care about Earth calendars, but only to the extent that they have to deal with Earth. Kind of like dealing with a different timezone on Earth. https://www.kimstanleyrobinson.info/content/martian-calendar https://www.kimstanleyrobinson.info/content/martian-calendar
- skissane 6y ago
  > However, having local time and a local calendar that are synchronized with when the sun comes up and the seasons I think makes a lot of sense How important are the seasons going to be for people who have to spend the vast majority of their time indoors due to the lack of a breathable atmosphere – and possibly even underground for protection against radiation? Maybe one day Mars will be terraformed and given a breathable atmosphere, and maybe even some kind of artificial magnetosphere can be created to protect against radiation. But that is going to take many centuries. The fact is that modern societies don't really need a calendar synchronised to the seasons. Most jobs nowadays the seasons are not very important. This is especially true in parts of the world where the difference in weather between the seasons is less marked (like where I live, here it never snows in winter). Fields such as agriculture where seasons are important can always keep track of the seasons independently from the calendar, or using a special purpose agricultural calendar. In fact, that's what is traditionally done in much of the Islamic world – the Islamic calendar was used for most purposes, which is out of sync with the seasons. Those jobs for which seasons were important, such as farmers, also used a separate solar calendar. It was only in the 20th century that the need to participate in the global economy created pressure to use the Gregorian calendar instead. > I like Kim Stanley Robinson's approach, as described in the Mars trilogy. They use standard seconds, but at 12:00 midnight, the clocks just stop for about 39 minutes I don't know why you'd do that. On earth, clocks run from 00:00:00 to 23:59:59 each day. On Mars, you'd just make them run to 24:39:34 instead. That way you can actually get precise times for events that occur in those extra 39 minutes and 35 seconds that happen each day. (Also, I'd hope people on Mars would be using 24 hour time–I'm one of those people who changes all their clocks to 24 hour time on Earth) > Martian colonies will still care about Earth calendars, but only to the extent that they have to deal with Earth For the first few decades at the very least, Martian colonies will be dealing with Earth an awful lot. A lot of goods will have to be imported from Earth. There will be a lot of focus on what they can locally manufacture on Mars, but they'll start with basic stuff like foodstuffs and simpler manufactured goods, and it will be a long time before Mars has leading-edge semiconductor fabs or a lot of other stuff like that. There will also be continual immigration from Earth, and also people returning to Earth (whether temporarily or permanently). That's going to psychologically link them with Earth. Martians are also going to consume a huge amount of cultural imports from Earth. You think on Mars they won't have Netflix, YouTube, etc? They'll replicate the content library into a Mars-based CDN and people will be watching it on Mars. It is going to take a long time before natively produced Martian media/entertainment content becomes more popular than the Earth-imported stuff. And I think that's going to tie Martians to Earth at least as much as trade ties and movement of people back and forth will. Martian colonies will undoubtedly develop some unique cultural aspects, but a huge amount of their culture is just going to be Earth imports.