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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

#101

Post by CydeWeys »

hopler wrote: post #98
CydeWeys wrote: post #65

Earlier quoted context omitted.

GPS satellites already control for relativistic effects. Their required accuracy is so high that they wouldn't work without doing so. You would simply also correct for relativistic effects caused by the orbits of different planets, and boom, you have a pretty consistently defined time that is valid across the entire solar system.

Consistently defined time is less useful when events at time 12:04 cause events at time 12:02

Can you give a concrete example of how that might happen?

Re: The Last POWER1 CPU on Mars Is Dead

#102

Post by omeid2 »

saagarjha wrote: post #90
omeid2 wrote: post #86

Earlier quoted context omitted.

> doing a calendar look-up for the time on Mars isn't as neat This is actually not that a big deal, in many countries, like Afghanistan and Iran, people observe 3 different calendars for different purposes and they all drift from each other! That is, 1st Jan (Georgian) is not always 24th Jaddi/Dey (Afghan/Iranian - Solar) nor 7th of 7th Jumada i-ula (Lunar/Islamic).. So people use calendars that look like this for ea…

That only works if days are the same length, no?

Nope, Gregorian Calendar and Solar calendar don't have exactly same days (although it is very small), and thus the different leap years.

Martian days being around 37 min longer, you might need more leap days though.

Re: The Last POWER1 CPU on Mars Is Dead

#103

Post by justinclift »

jakeinspace wrote: post #87
oso2k wrote: post #68

Earlier quoted context omitted.

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 a coincidence, I'm working on the core flight system project right now, which includes an implementation of CCSDS File Delivery Protocol. You might be happy to know that project is still very much alive within NASA (you were probably already aware).

Fairly off topic ;), but any idea if SQLite is used on any of the rovers, spacecraft, etc?

Mostly from idle curiosity. Was wondering a few days ago and guessing "probably yes", but no idea who to ask.

So, taking the opportunity (heh) now. :)

Re: The Last POWER1 CPU on Mars Is Dead

#104

Post by sagartewari01 »

JumpCrisscross wrote: post #9
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 fundamentally cannot exist. Any "universal" system would drift for observers on different planets. Having different times in New York and New Delhi isn't the worst right now; doing a calendar look-up for the time on Mars isn't as neat. But given we won't have real-time communication, it isn't as big of a problem e…

It doesn't appear to be impossible.

Setup a transmitter at earth which emits a signal at uniform intervals containing current time (seconds since kanye west's marriage). An observer can then deduce current time if it knows where it is. I don't think relativistic dilation would effect this method.

With multiple such emitters synchronized with each other, one might even be able to 'triangulate' the current time. (I haven't worked out any details)

Re: The Last POWER1 CPU on Mars Is Dead

#105

Post by artursapek »

sagartewari01 wrote: post #104
JumpCrisscross wrote: post #9

Earlier quoted context omitted.

> Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? This fundamentally cannot exist. Any "universal" system would drift for observers on different planets. Having different times in New York and New Delhi isn't the worst right now; doing a calendar look-up for the time on Mars isn't as neat. But given we won't have real-time communication, it isn't as big of a problem e…

It doesn't appear to be impossible. Setup a transmitter at earth which emits a signal at uniform intervals containing current time (seconds since kanye west's marriage). An observer can then deduce current time if it knows where it is. I don't think relativistic dilation would effect this method. With multiple such emitters synchronized with each other, one might even be able to 'triangulate' the current time. (I hav…

Would the Y2K bug then be the possibility of Kanye and Kim getting divorced?

Re: The Last POWER1 CPU on Mars Is Dead

#106

Post by Terr_ »

sagartewari01 wrote: post #104
JumpCrisscross wrote: post #9

Earlier quoted context omitted.

> Do we humans have plans in the pipeline for a universal time standard we can use wherever we are? This fundamentally cannot exist. Any "universal" system would drift for observers on different planets. Having different times in New York and New Delhi isn't the worst right now; doing a calendar look-up for the time on Mars isn't as neat. But given we won't have real-time communication, it isn't as big of a problem e…

It doesn't appear to be impossible. Setup a transmitter at earth which emits a signal at uniform intervals containing current time (seconds since kanye west's marriage). An observer can then deduce current time if it knows where it is. I don't think relativistic dilation would effect this method. With multiple such emitters synchronized with each other, one might even be able to 'triangulate' the current time. (I hav…

I'm not sure what you're trying to say here.

We've known since the Viking landers of the 70s that clocks on Mars don't run the same as on Earth, and that's not even accounting for the speed-effects as the Earth keeps "lapping" Mars on their respective race around the sun.

Re: The Last POWER1 CPU on Mars Is Dead

#107

Post by jakeinspace »

justinclift wrote: post #103
jakeinspace wrote: post #87

Earlier quoted context omitted.

What a coincidence, I'm working on the core flight system project right now, which includes an implementation of CCSDS File Delivery Protocol. You might be happy to know that project is still very much alive within NASA (you were probably already aware).

Fairly off topic ;), but any idea if SQLite is used on any of the rovers, spacecraft, etc? Mostly from idle curiosity. Was wondering a few days ago and guessing "probably yes", but no idea who to ask. So, taking the opportunity (heh) now. :)

I don't know about rovers, but some smaller spacecraft (mainly satellites) use mysql, as well as postgres. Disclaimer: I'm not the right person to ask.

Re: The Last POWER1 CPU on Mars Is Dead

#108

Post by hinkley »

omeid2 wrote: post #102
saagarjha wrote: post #90

Earlier quoted context omitted.

That only works if days are the same length, no?

Nope, Gregorian Calendar and Solar calendar don't have exactly same days (although it is very small), and thus the different leap years. Martian days being around 37 min longer, you might need more leap days though.

Leap days are caused by one revolution not being a whole number of rotations.

The weird thing with Mars would be that if you contact someone at 5pm local today it might not be okay to call them at the same time tomorrow, because they would clock in 37 minutes later.

Re: The Last POWER1 CPU on Mars Is Dead

#109

Post by djsumdog »

JumpCrisscross wrote: post #9
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 fundamentally cannot exist. Any "universal" system would drift for observers on different planets. Having different times in New York and New Delhi isn't the worst right now; doing a calendar look-up for the time on Mars isn't as neat. But given we won't have real-time communication, it isn't as big of a problem e…

I forget how this was accounted for in Kim Stanley Robin's famous Mars trilogy (highly recommend; best Sci-Fi book I've ever read). I think Earth and Mars were so far apart with time delays and everything else that Martian days/years took on a meaning of their own.

Re: The Last POWER1 CPU on Mars Is Dead

#110

Post by oso2k »

justinclift wrote: post #103
jakeinspace wrote: post #87

Earlier quoted context omitted.

What a coincidence, I'm working on the core flight system project right now, which includes an implementation of CCSDS File Delivery Protocol. You might be happy to know that project is still very much alive within NASA (you were probably already aware).

Fairly off topic ;), but any idea if SQLite is used on any of the rovers, spacecraft, etc? Mostly from idle curiosity. Was wondering a few days ago and guessing "probably yes", but no idea who to ask. So, taking the opportunity (heh) now. :)

The small parts of the Mars Rovers (MER) I worked on or worked with didn’t use SQLite. It was too early in SQLite’s history for it to be used on MER. MER also used VxWorks which probably didn’t have a lot in the way of POSIX support at the time. I remember other devs telling me the fun they had supporting 1553 bus on “such a new RTOS”.

Wikipedia say MSL used VxWorks as well.

I’d have to ask a buddy still doing Mission Ops Support at JPL but I’d think the answer is no SQLite on MER or MSL missions. The OSes were fairly custom, non-POSIX builds. The ESA folks might have tried though on their missions.

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