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Becky Black
06-25-2015, 02:01 PM
So in my story there was a zombie apocalypse a couple of years ago and there are only a small number of scattered survivors scratching a living as best they can (though that's about to change.)

My question is, can people still use GPS to navigate at sea and on land? The satellites are still up there. The people have power to their GPS devices. But I know there are ground stations that are part of the system. In this post-apocalypse world where nobody is staffing the ground stations, is the system still usable from the satellites?

Yes or no both work fine for my story - they'll figure the way eventually.

Related - what about plane navigation in this situation, where the pilot has nothing from the ground to help? ATC is not going to be that big a problem as there are no other planes around to avoid. But can she still find her way to her destination - in this case to Duluth Airport starting from north west Ontario?

Thanks in advance for any help!

Helix
06-25-2015, 02:07 PM
They could always find their way around with the 'old-fashioned' method of using maps and compasses.

Becky Black
06-25-2015, 02:23 PM
They could always find their way around with the 'old-fashioned' method of using maps and compasses.

I'll make them do that if they have to. And all the road signs are still there to point the way - once they get to some place with roads. They're very isolated right now.

I just don't want to either have them not use GPS and have some people wondering why they don't, or using it and having people say "that wouldn't be possible."

oceansoul
06-25-2015, 03:27 PM
I think you could have a GPS that worked off satelitte? That way the thing powering/controlling it would be in space, and so wouldn't have been destroyed in anything happening on earth. I would probably be able to suspend disbelief for that if I was reading.

Thewitt
06-25-2015, 03:33 PM
GPS works off satellite today. They would keep working until the satellites failed - and they will fail sporadically, so it will be better in some places than others.

WikiPedia is your friend... https://en.wikipedia.org/wiki/Global_Positioning_System

Chris P
06-25-2015, 03:35 PM
They still had it in Peter Heller's The Dog Stars, but of course that doesn't make it scientific fact.

Manuel Royal
06-25-2015, 04:24 PM
The GPS system relies on frequent ground-based clock resynchronization and occasional directions for satellite repositioning. (The precision needed is so high you have to account for relativistic effects.) I wouldn't expect good accuracy after two years unattended. (I wouldn't be surprised if satellites take themselves offline before then.)

I would bet all the money I'll ever have that this specific question has been dealt with on other message boards, blogs, etc. I'm doing a basic search ... okay, I typed in (to Google) "how long would gps work" and it autofilled "after apocalypse". 392,000 results. Don't know if there's a definitive answer available.

If I were doing the story, I think I'd have the GPS be unreliable, and not mention it much. Fortunately, individual electronic devices should work, so I'd have my characters look for a precise chronometer and an electronic sextant.

(One of the irritating things on the show The Walking Dead is they don't often make use of technology that should still work. Like shortwave radios ... books ... road maps ....)

cornflake
06-26-2015, 06:03 AM
Are ALL the satellites still there? That seems highly unlikely. Even more unlikely to think they're all still online and communicating with whatever is around. Though I'd wonder about a lot of things working fine, like power, especially places it'd have been interrupted or had stuff happen that no one fixed.

T Robinson
06-26-2015, 06:08 AM
So in my story there was a zombie apocalypse a couple of years ago and there are only a small number of scattered survivors scratching a living as best they can (though that's about to change.)

My question is, can people still use GPS to navigate at sea and on land? The satellites are still up there. The people have power to their GPS devices. But I know there are ground stations that are part of the system. In this post-apocalypse world where nobody is staffing the ground stations, is the system still usable from the satellites?

Yes or no both work fine for my story - they'll figure the way eventually.

Related - what about plane navigation in this situation, where the pilot has nothing from the ground to help? ATC is not going to be that big a problem as there are no other planes around to avoid. But can she still find her way to her destination - in this case to Duluth Airport starting from north west Ontario?

Thanks in advance for any help!

Duluth, Georgia or Duluth, Minnesota?

Roxxsmom
06-26-2015, 06:25 AM
But stupid people who follow gps to their doom is a great plot device. When zombies drive.

http://www.cracked.com/quick-fixes/the-8-most-hilarious-ways-gps-has-screwed-people-over/

http://www.people.com/article/car-drives-off-bridge-GPS-chicago-cline-woman-killed

http://www.sacbee.com/entertainment/living/travel/article2573180.html

Becky Black
06-26-2015, 12:31 PM
GPS works off satellite today. They would keep working until the satellites failed - and they will fail sporadically, so it will be better in some places than others.

WikiPedia is your friend... https://en.wikipedia.org/wiki/Global_Positioning_System

I read that page but a lot of it was over my head. :D

Becky Black
06-26-2015, 12:39 PM
The GPS system relies on frequent ground-based clock resynchronization and occasional directions for satellite repositioning. (The precision needed is so high you have to account for relativistic effects.) I wouldn't expect good accuracy after two years unattended. (I wouldn't be surprised if satellites take themselves offline before then.)

That's what I was thinking, that the ground stations make adjustments to the satellites and one that's not happening they'd become unreliable.


I would bet all the money I'll ever have that this specific question has been dealt with on other message boards, blogs, etc. I'm doing a basic search ... okay, I typed in (to Google) "how long would gps work" and it autofilled "after apocalypse". 392,000 results. Don't know if there's a definitive answer available.

LOL, the things we ask on the internet...


If I were doing the story, I think I'd have the GPS be unreliable, and not mention it much. Fortunately, individual electronic devices should work, so I'd have my characters look for a precise chronometer and an electronic sextant.

I think you're right it's best not to let them rely in it. They'll find their way without it.


(One of the irritating things on the show The Walking Dead is they don't often make use of technology that should still work. Like shortwave radios ... books ... road maps ....)

I know! Shortwave especially. In this book and the once that came before, the survivors are scattered, but some groups are in touch with each other using shortwave radio. In fact the radio is about to bring some news that's going to change everything for my characters.

Becky Black
06-26-2015, 12:49 PM
Are ALL the satellites still there? That seems highly unlikely. Even more unlikely to think they're all still online and communicating with whatever is around. Though I'd wonder about a lot of things working fine, like power, especially places it'd have been interrupted or had stuff happen that no one fixed.

Would the satellites fall out of orbit if ground stations don't adjust their orbits periodically? Or drift from the positions they are supposed to be in?

My group have power from a generator and solar panels, but mains power is definitely off everywhere.

Becky Black
06-26-2015, 12:53 PM
Duluth, Georgia or Duluth, Minnesota?

Minnesota. That's about as far as the pane they have will get them before needing refuelled. And they've chosen it for a few other reasons over nearby ones. They plan to either refuel the plane and fly on, and if they can't do so, take to the roads. But they've gotta have that plane to get them across the roadless wilderness that is northern Ontario! :D

Becky Black
06-26-2015, 12:56 PM
But stupid people who follow gps to their doom is a great plot device. When zombies drive.

http://www.cracked.com/quick-fixes/the-8-most-hilarious-ways-gps-has-screwed-people-over/

http://www.people.com/article/car-drives-off-bridge-GPS-chicago-cline-woman-killed

http://www.sacbee.com/entertainment/living/travel/article2573180.html

Eejits. The people who let their sat nav override their common sense should not be at the wheel of a car. :rant:

Becky Black
06-26-2015, 01:02 PM
Thanks all for the replies. I think they'll have to stick with good old fashioned methods of navigation. Once they are on the roads in the US, maps exist, they have an ex-military guy and a pilot in the group, who can read a map and a compass properly. Road signs will mostly still be there. They'll get to where they are going in the end.

King Neptune
06-26-2015, 04:59 PM
Eejits. The people who let their sat nav override their common sense should not be at the wheel of a car. :rant:

There are machine controlled vehicles now, so remember this.

Becky Black
06-26-2015, 07:34 PM
There are machine controlled vehicles now, so remember this.

We're so gonna need manual override on those things.

"Sorry I'm late for work. My robot car took me to Aberdeen."

King Neptune
06-26-2015, 09:50 PM
We're so gonna need manual override on those things.

"Sorry I'm late for work. My robot car took me to Aberdeen."

Two computer controlled cars had a close but not quite encounter yesterday. I haven't seen anything on whether they get lost, but there probably are times when they don't do well. Google has admitted that its unmanned cars have been involved in many accidents, but it didn't give a rate per mile travelled; that would be the important statistic.

Serenity Bear
06-26-2015, 09:54 PM
I presume GPS gadgets need battery power, or can you get solar powered GPS thingies now. The battery life wont last for every BUT you can get solar powered chargers that will power up gadgets with the correct bit to connect them with. Most in the know use both GPS and maps with a compass, never rely on just one. Even with a compass one should carry two, because the A typical survival pyschology will make you doubt that one might be broken when you get lost, but don't want the reality of it. Would they carry two GPS I wonder!

cbenoi1
06-27-2015, 12:42 AM
> Related - what about plane navigation in this situation, where the pilot has nothing from the ground to help?

Pilotage & dead reckoning. It's part of basic training for pilots.


> But they've gotta have that plane to get them across the roadless wilderness that is northern Ontario!

You can pretend they are following the power lines, one that happens to end at Thunder Bay or some other town on Lake Superior. They could refuel there, then follow the coastline to Duluth.

Also, I'm seeing a few NDBs along the route from Ft Severn (CYER) and Thunder Bay (CYQT), all within reasonable range to one another. NDB stations are cheap to operate, and they were the backbone of the Canadian artic navigation system for decades before GPS. Most general aviation planes with the older 'steam gauges' avionics still have that clunky ADF radio finder on their instrument panels, so it's not unreasonable to fly some old airways from Hudson's Bay to Lake Superior.

-cb

blacbird
06-27-2015, 05:15 AM
Without somebody to constantly maintain the GPS satellites (of which there are twenty-some), GPS is quickly useless. Among other things, to keep time correctly on these satellites, the effects of relativity to time have to be dealt with.

caw

WeaselFire
06-28-2015, 03:45 PM
Where is the pilot getting the plane fueled and why would they be flying when there is no civilization left? Who is running the power plants for them to get the electricity to charge the GPS devices? What is your reasoning for some technology, like electricity, GPS and airline navigation, being available after a total collapse of society? Might want to look up Maslow's Hierarchy to add some basic motivations into why people do what they do.

Although George Romero did populate a mall with zombies because "It was a place that was important to them when they were alive."

Jeff

Becky Black
06-29-2015, 12:44 PM
Where is the pilot getting the plane fueled and why would they be flying when there is no civilization left? Who is running the power plants for them to get the electricity to charge the GPS devices? What is your reasoning for some technology, like electricity, GPS and airline navigation, being available after a total collapse of society? Might want to look up Maslow's Hierarchy to add some basic motivations into why people do what they do.

Although George Romero did populate a mall with zombies because "It was a place that was important to them when they were alive."

Jeff

They're in an isolated place and have a generator - which they use sparingly - and solar power. No mains power. No power stations are running. They could charge the devices if they want to. The plane is at an airport that they can get to from where they are and there is plenty of fuel there and also some people who once worked at the airport, so they can get the plane fueled. I've got a question about the viability of the fuel after that time, but I'm researching that.

They're going to find another specific group of survivors, and they've got to leave where they are anyway, as living there isn't sustainable much longer.

The airline navigation, as in Air Traffic Control and radio signals and radar on the ground isn't working, that's why I was asking about how the pilot would manage without those.

Becky Black
06-29-2015, 12:46 PM
I presume GPS gadgets need battery power, or can you get solar powered GPS thingies now. The battery life wont last for every BUT you can get solar powered chargers that will power up gadgets with the correct bit to connect them with. Most in the know use both GPS and maps with a compass, never rely on just one. Even with a compass one should carry two, because the A typical survival pyschology will make you doubt that one might be broken when you get lost, but don't want the reality of it. Would they carry two GPS I wonder!

Compasses on standby. In fact that gives me an idea to have the ones in the group who do know how to use those teach the ones who don't how to correctly use a map and/or a compass to get around

Becky Black
06-29-2015, 12:53 PM
> Related - what about plane navigation in this situation, where the pilot has nothing from the ground to help?

Pilotage & dead reckoning. It's part of basic training for pilots.

She is a veteran bush pilot, so she probably thinks using anything but dead reckoning is soft. ;)


> But they've gotta have that plane to get them across the roadless wilderness that is northern Ontario!

You can pretend they are following the power lines, one that happens to end at Thunder Bay or some other town on Lake Superior. They could refuel there, then follow the coastline to Duluth.

Also, I'm seeing a few NDBs along the route from Ft Severn (CYER) and Thunder Bay (CYQT), all within reasonable range to one another. NDB stations are cheap to operate, and they were the backbone of the Canadian artic navigation system for decades before GPS. Most general aviation planes with the older 'steam gauges' avionics still have that clunky ADF radio finder on their instrument panels, so it's not unreasonable to fly some old airways from Hudson's Bay to Lake Superior.

-cb

Thanks!

At the minute I've got them flying from Moosonee, so I was thinking that they could follow the railway line from there for a good long way. The pilot will find other landmarks after that. And of course as you say the coastline of Lake Superior to their destination.

Becky Black
06-29-2015, 12:54 PM
Without somebody to constantly maintain the GPS satellites (of which there are twenty-some), GPS is quickly useless. Among other things, to keep time correctly on these satellites, the effects of relativity to time have to be dealt with.

caw

That's what I suspected. That there must be adjustments being made from the ground and without that they'd become unreliable.