Land Navigation

[HSlam]

Not so much a rules question as a general process question...

How do you folks deal with land navigation and coordinates on frontier/unexplored/low tech planets? No GPS satellites in orbit, and maybe not even any prior maps - which raises the question of how you establish a zero line for longitude?

The question came up in rather esoteric circumstances. The players left a briefcase on a very small island (about four total acres) on a planet full of nothing but between 15 - 16 thousand very small islands. The planet is outside Imperial Space, no maps in their database, how do they go back and find that one specific island?

 

[legozhodani]

Quite a challenge! What tech level are the PCs?

 

[ShawnDriscoll]

I have maps of worlds. The players' characters may or may not have been keeping track of where they've been on a world. Sometimes it comes down to a skill check to see if they know where to go, unless they've been role-playing and have something to make a callback to. Otherwise, they continue on without it.

 

[fusor]

Not so much a rules question as a general process question...

How do you folks deal with land navigation and coordinates on frontier/unexplored/low tech planets? No GPS satellites in orbit, and maybe not even any prior maps - which raises the question of how you establish a zero line for longitude?

The question came up in rather esoteric circumstances. The players left a briefcase on a very small island (about four total acres) on a planet full of nothing but between 15 - 16 thousand very small islands. The planet is outside Imperial Space, no maps in their database, how do they go back and find that one specific island?

By memory? Did they see if there were any islands nearby? If they recall that there was an island to the north and another to the south east (and one further than that in roughly the same direction) then they can go back, map the planet from space at sufficient resolution to detect that size of island, and see (or more likely run a program to see) if they can find that configuration of islands?

Also, Zero longitude would be pretty arbitrary on a rotating planet - just pick a landmark (e.g. the centre of the biggest island, location of the first settlement, etc). Or if the planet's tidelocked then pick the longitude that contains the sub-solar point (or sub-planet point, if it's a moon tidelocked to a planet).

 

[HSlam]

In this case the players are TL 13.

Its not so much whether or not I have maps or they've been taking notes... latitude and longitude work. The problem is setting a zero longitude if no zero is currently mapped out.

Now if there were GPS satellites there would be no problem, and I'm assuming the Imperium would have a master reference of all it's charted planets that would include each planet's version of a greenwich line.

The problem is uncharted worlds. Astronomy has a way to reference a very gross longitude "zero" based on the planet's pole compared to the system's plane and how it relates to the galactic plane. This kinda works just to be able to define east and west but its way too gross to (for example) set a coordinate to make an inertial reference guidance system work.

furor, yep, setting zero would be kinda easy as long as the party remembers to do it (or if their ship software is 'smart' enough to do it automatically when it encounters an unknown world). In this particular case the players could be screwed because they didn't set any kind of reference whatsoever.

The weird part (to me) is that the problem is kinda magnified in border regions of space. What happens to directions and coordinates on a given world when Azlan maps use a different zero longitude than Imperial maps do? (just as an example question)

 

[ShawnDriscoll]

The weird part (to me) is that the problem is kinda magnified in border regions of space. What happens to directions and coordinates on a given world when Azlan maps use a different zero longitude than Imperial maps do? (just as an example question)

The same thing happens when you look at two current Earth maps created by two vary different cultures. You use the one from yours. Or you start mapping the planet the first time you orbit it, if there is no map. A skill check can determine if a map can be converted to another format.

 

[Tenacious-Techhunter]

When the ship’s sensors mapped the planet, it would have picked a few reasonably useful points of reference automatically; something that could be identified even under adverse conditions. The location the magnetic pole deviates from the axis of rotation, a cluster of easily identified volcanoes, a cluster of radioactive isotopes, a lake in a continent-sized island, and so on. Since the players bothered to go there, those maps are already in the Ship’s Flight Computer History, if not also as a database entry. While not as easy as looking up a deliberately prepared map made by the crew itself with reference points directly relevant to the party members (“There’s that big mountain we saw!”), it’s still in a file somewhere; the players just have to dig it out, open it up, and do some orienteering.

 

[legozhodani]

Pretty much what T-T said. A basic sweep on the surface maybe in the data banks. Requires a few rolls to pin the location down to a rough area. Then it's down to the PCs to do it the hard way. Navigation and survival, maybe recon would help recall features and start to narrow down the options.

Best of luck to them.

 

[nats]

They spend the rest of their lives looking for it. Sounds like a movie in the making. Anyone who has tried playing Minecraft without a map will know how easy it is to get lost. If their scanners can pick up something that small (doubtful) they could spend a few hours scanning during low passes, but me I would say they should have thought to make a map so they are stuffed. The consequences of that are probably far more entertaining than allowing them to find it 'by magic', especially if the briefcase contains sensitive information or drugs belonging to a local crime lord or whatever.

 

[Condottiere]

Zero longitude, Downport or capital city.

 

[HSlam]

Thanks for the thoughts folks, helps a lot.

still need to do some thinking on featureless and balkanized planets but you've given me some great starting points

 

[Tenacious-Techhunter]

Zero longitude, Downport or capital city.

That doesn’t help for “frontier” or “unexplored”.

 

[Tenacious-Techhunter]

Thanks for the thoughts folks, helps a lot.

still need to do some thinking on featureless and balkanized planets but you've given me some great starting points

Define “featureless”.

The governments of Balkanized planets will be more than happy to share the geographic details corresponding to the territories they are fighting over, since they insist that it’s theirs on a regular basis. Governments on Balkanized planets have issues with each other, not with Travellers, per se, although allowing Travellers to visit is a frequent point of contention.

 

[fusor]

Shockingly, planetary cartographers have been pondering this problem for a while:
http://www.planetary.org/blogs/emily-lakdawalla/2013/07301442-plutosci-zangari-cartography.html

 

[wbnc]

land navigation is not hard if there is a moon, or prominent star in the night sky. a traveller could assign an arbitrary point as the prime meridian, then designate a point halfway between the physical north and south pole of the planet as the equator. then a simple computer program could compute location on a sphere east/west north south of that point by taking a sighting using a fairly basic sextant device. all you need is the orbital data for a system, and a computer can project sunrise, sunset, and noon time locations in the sky for any celestial object.it's fairly detailed math, but easy for a ship computer. after all it has the processing power of every computer on the entire planet during the moon shot era.And simple geometry isnt nearly as advanced as computing jump vectors through hyperspace.

If they have radar data from when they left the island the first time they can pull the logs and get the shape of the island on radar.

a starship with even basic sensors could map an entire world rather quickly with radar. a computer could run it's survey data..and eliminate islands that aren't the right shape. even basic radar scans would be able to generate a very detailed map of the planet in a day or two as it approached the planet from the jump limit. Nasa has built a fairly accurate radar map of Earth using our current level of tech so at TL-12-14 a standard ships radar and ships computer could do it nicely.a Crewman with the right skills could both compile the data into a useful form and then create a nifty map for their own use.

then there is the most basic form of navigation.... dead reckoning...Basically its..."we flew two hours at 300kph on this course to get back to our ship, so if we fly 300Kph on a reciprocal course that will put us in the general area". If they don't know their flight time they could pull it off the logs from the navigation system of whatever vehicle they were using ( if it has one)

 

[fusor]

a starship with even basic sensors could map an entire world rather quickly with radar. a computer could run it's survey data..and eliminate islands that aren't the right shape. even basic radar scans would be able to generate a very detailed map of the planet in a day or two as it approached the planet from the jump limit. Nasa has built a fairly accurate radar map of Earth using our current level of tech so at TL-12-14 a standard ships radar and ships computer could do it nicely.a Crewman with the right skills could both compile the data into a useful form and then create a nifty map for their own use.

Um, do you know how long it takes to compile those global maps at a decent resolution? You won't be able to do it "as you approach the planet from the jump limit", you need to be in a close orbit around the planet covering tiny strips of the planet's surface with each orbit to get high resolution data, and you need a lot of orbits to get the whole planet (and then you need to calibrate and clean up the data, etc). It's not a trivial task, even at higher TLs (it certainly wouldn't be standard kit for ships).

 

[ShawnDriscoll]

Um, do you know how long it takes to compile those global maps at a decent resolution? You won't be able to do it "as you approach the planet from the jump limit", you need to be in a close orbit around the planet covering tiny strips of the planet's surface with each orbit to get high resolution data, and you need a lot of orbits to get the whole planet (and then you need to calibrate and clean up the data, etc). It's not a trivial task, even at higher TLs (it certainly wouldn't be standard kit for ships).

He's been to the 57th century.

 

[Reynard]

Frontier and/or unexplored readily states no one with the ability has established any cartographic standards for that particular world. That means the Travellers are the soon to be standard. Why do they need to know? Are they exploring or is there an emergency that traps them there? If this is planned then they would be taking the time to do at least a macro orbital survey. They will establish zero longitude because they were there first. Longitude on Earth isn't there by some logical scientific reason, Britain called dibs and not enough people argued about it. I assume they locate a very outstanding planetary feature they can pinpoint. Best would be placing something on the preferred spot as a readily locatable marker from a gigantic 'X' laser etched into the rock or a primary broadcasting beacon. Obviously latitude will be easier by observing a day or more of planetary rotation. If space travel is common enough, dividing the two coordinates with involve a standard system such as macro units of 360 degrees and distance based on the size of the world.

 

[HSlam]

Thanks for the thoughts folks, helps a lot.

still need to do some thinking on featureless and balkanized planets but you've given me some great starting points

Define “featureless”.

The governments of Balkanized planets will be more than happy to share the geographic details corresponding to the territories they are fighting over, since they insist that it’s theirs on a regular basis. Governments on Balkanized planets have issues with each other, not with Travellers, per se, although allowing Travellers to visit is a frequent point of contention.

I suppose I'm meaning featureless as in a liquid covered planet (or in the case of the original question: very nearly liquid covered, merely spotted by many many thousands of less-than-ten-acre islands). Of course, if you've got a really really good orbital sensor I suppose you could use an ocean floor feature.

Or featureless like a dune planet that's entirely shifting sand dunes.

Or even featureless like a fairly uniform lava-like covering with no significant elevation changes.


I guess nothing is really and truly "featureless" if you look at it closely enough - the question then becomes how long you're willing to look to define a feature.

 

[Condottiere]

Lighthouse beacon.

Where? Noon, on the Emperor's Birthday.