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The Last POWER1 CPU on Mars Is Dead

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Re: The Last POWER1 CPU on Mars Is Dead

#71

Post by twic »

yingw787 wrote: post #5

Might be O/T, but I found it really interesting how they mention "5,352 Martian solar days". Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? Something that is a little more useful than "seconds since UNIX epoch" but something a little less terrestrial than UTC? Or is time going to be based wherever we land or travel (e.g. divide up Mars into time zones upon colonizati…

Universal, no. But the Darian calendar system has been carefully devised to fit Mars, the moons of Jupiter, and Titan, and as far as i know that's the closest anyone has got:

http://ops-alaska.com/time/gangale_mst/abstract.htm

Re: The Last POWER1 CPU on Mars Is Dead

#72

Post by Retric »

etaoins wrote: post #59
yingw787 wrote: post #33

Earlier quoted context omitted.

I know that system clock drift can be bounded to milliseconds using an atomic clock or GPS receiver, but I didn't know whether we could overcome synchronization difficulties when speed-of-light differences are significant. I thought we could package some coordinate reference system, directional travel metadata (I'm traveling 0.000002c this way), and current system clock time, and synchronize that way. Fantasy use cas…

There is Barycentric Coordinate Time which is the time from a hypothetical clock at rest at the centre of mass of the Solar System. This is easier to calculate across spacecraft than an Earth-centric time would be. However, because it's outside of Earth's gravity well it ticks slightly faster than Earth time.

While true it’s still trivial to do such calculations and then output in GMT or whatever. In theory such calculations can get really messy, but atomic clocks are still not accurate enough to make a huge range of minor issues important.

For example we are not just in the sun’s and earth’s gravity field but also the other planets as well. So, with enough precision you would need to account for their locations.

Re: The Last POWER1 CPU on Mars Is Dead

#73

Post by yingw787 »

simcop2387 wrote: post #47
yingw787 wrote: post #43

Earlier quoted context omitted.

Hmm...would this only be relevant on the scale of nano/picoseconds, or seconds or higher granularity, given a frequent synchronization schedule?

For any speeds we'd be likely to be traveling, in system, it'd likely only be a problem for milliseconds if that. We'd still be able to correct for where things are as we approach them or plan to approach them.

Yeah, I was thinking only of in the Solar System. Beyond that, the primary bound on commercializeable space is probably spacecraft propulsion, which will take a while.

Re: The Last POWER1 CPU on Mars Is Dead

#74

Post by basicplus2 »

yingw787 wrote: post #5

Might be O/T, but I found it really interesting how they mention "5,352 Martian solar days". Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? Something that is a little more useful than "seconds since UNIX epoch" but something a little less terrestrial than UTC? Or is time going to be based wherever we land or travel (e.g. divide up Mars into time zones upon colonizati…

A system based on SpaceTime with reference to the centre of the universe

Re: The Last POWER1 CPU on Mars Is Dead

#76

Post by yingw787 »

twic wrote: post #67
yingw787 wrote: post #5

Might be O/T, but I found it really interesting how they mention "5,352 Martian solar days". Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? Something that is a little more useful than "seconds since UNIX epoch" but something a little less terrestrial than UTC? Or is time going to be based wherever we land or travel (e.g. divide up Mars into time zones upon colonizati…

> Something that is a little more useful than "seconds since UNIX epoch" Milliseconds since UNIX epoch!

I'm not sure about the usefulness of increasing precision if you can only guarantee a certain precision upon synchronization. I wonder if increased clock activity translates to increased clock temperature and increased clock variation. And I worry about more frequent logging and disk usage/space.

But one thing I am sure of -- we would make good friends ;)

Re: The Last POWER1 CPU on Mars Is Dead

#77

Post by kanox »

nraynaud wrote: post #11
yingw787 wrote: post #5

Might be O/T, but I found it really interesting how they mention "5,352 Martian solar days". Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? Something that is a little more useful than "seconds since UNIX epoch" but something a little less terrestrial than UTC? Or is time going to be based wherever we land or travel (e.g. divide up Mars into time zones upon colonizati…

recently I was wondering about time keeping on Mars, did they create a local clock network like we have with UTC here?

Every lander/rover keeps track of local solar time independently so they're effectively each in a separate timezone.

I don't know what the orbiters use, presumably some variant of Julian day.

Re: The Last POWER1 CPU on Mars Is Dead

#78

Post by gcb0 »

oso2k wrote: post #68
gonehome wrote: post #54

Earlier quoted context omitted.

Somewhat comically J.C.R Licklider's first proposal for what became the internet was titled the Intergalactic Computer Network. He later said he did this because when the project is inevitably downsized it would at least cover the earth. Interplanetary internet designs and peering are interesting problems to think about though. https://en.wikipedia.org/wiki/Intergalactic_Computer_Network

There are real, standardized protocols [0] for this sort of thing, now. Early in my career, when I worked at JPL/NASA, I did a bit of work to test these protocols on Linux in a simulated Network of spacecraft. Fun stuff! [0] https://en.wikipedia.org/wiki/CCSDS_File_Delivery_Protocol

What does it use for time? The spec mentions time in a lot of places, but never defines it. There is even a field to communicate light-time but no mention of how to synchronize anything. I guess this runs on top of another protocol that solves it? Any idea what it is?

Re: The Last POWER1 CPU on Mars Is Dead

#79

Post by kanox »

yingw787 wrote: post #5

Might be O/T, but I found it really interesting how they mention "5,352 Martian solar days". Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? Something that is a little more useful than "seconds since UNIX epoch" but something a little less terrestrial than UTC? Or is time going to be based wherever we land or travel (e.g. divide up Mars into time zones upon colonizati…

> Do we humans have plans in the pipeline for a universal time standard we can use wherever we are?

Astronomy generally uses "Julian days" or "Julian years" which are measured in seconds since a certain calendar date. Since they're based on SI seconds intervals are independent of the Earth's movement and leap seconds and all that nonsense.

Most popular epoch is J2000: measured since noon on 1 January 2000.

Mars landers each track local solar time separately and a colony is likely to invent its own timezone with 24 hours and 39 minute days. You need this so that notions like "sunrise" and "sunset" make sense.

Re: The Last POWER1 CPU on Mars Is Dead

#80

Post by myself248 »

jrnichols wrote: post #20
yingw787 wrote: post #5

Might be O/T, but I found it really interesting how they mention "5,352 Martian solar days". Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? Something that is a little more useful than "seconds since UNIX epoch" but something a little less terrestrial than UTC? Or is time going to be based wherever we land or travel (e.g. divide up Mars into time zones upon colonizati…

> Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? this made me think of Swatch Internet Time, and whether or not it could have worked. https://en.wikipedia.org/wiki/Swatch_Internet_Time

The reason I haven't tried to revive Swatch Internet Time is that it was based in GMT+1, which is just inane. I don't know if that little detail offended anyone else, but it sure torpedoed the idea for me.
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