OTU Only: Satellites sometimes obsolete in the OTU?

[Fritz_Brown]

How do you tether that thing "Stationary"? As in "still"? Also, how blessed many are going to be needed? And, how do you recharge the lift gas?

Moving a few feet doesn't matter if it's omnidirectional communications. It can swing at the end of a single tether, or be tethered at each end. Even for locator beacons, it wouldn't make much difference unless you're targeting weapons or the people are too dumb *not* to follow the GPS when it says to turn down the railroad tracks.

The coverage will be limited, but not as limited as towers, and would require lower transmitter power than going to satellites.

As for recharge, you could conceivably recharge it from the atmo, or run a line up to it. You *would* want to pull it down once in a while to maintain it, though - leaving you with a hole in your coverage.

Mostly, airships would be useful to extend the range of communications temporarily (like a disaster that takes out the permanent towers), or perhaps in an exploratory mission. (You could have an airship above your expedition, relaying to satellites and to base camp, as you moved along.) They would work especially well in an ATU without contragrav, or if you take the tack that the only "gravitics" that works in a gravity well is contragrav (meaning you would still need another sort of propulsion to do station-keeping with that atmospheric contragrav comm platform).

 

[Fritz_Brown]

McPerth, I have problems with powersats. Besides having to burn through the atmospheric interference, you would have to create no-fly zones around all those beams. You would also still have to create a largish distribution network. With compact/modular nukes you can do everything locally, and if they're hydrogen-based fusion, the fuel is abundant.

 

[rancke]

Why would any world with a Starport (Type A-E, excluding X) not have a ring of baseball sized objects in low orbit or geostationary orbit to simply and easily meet all of its imaging, weather and communications needs?

For one thing, someone has to be willing to pay for them; for another, anything valuable in orbit around a world that doesn't have system defenses is just an invitation to scavengers.


Hans

 

[robject]

1. Communications and Positioning. Commsats are probably the best solution until meson technology (TL14?), after which commsats become secondaries, or even space junk for the reclamation industry. Although, suborbital gravitics solutions, if reliable enough, can replace commsats earlier where atmospheres and governments are cooperative.

2. Powersats. Beamed power stations are useful until fusion goes commercial, after which they become space junk for the reclamation industry.

3. Interdiction. These are useful until beam weapons are installed which can reach out of the atmosphere. I think. There's no guarantee that a world will replace interdiction sats ever, though; they could be carried as sensor pickets or secondaries.

4. Weather and Imaging. These satellites are useful unless the world has a reliable gravitics-based suborbital solution. The technology exists on TL8+ worlds, but implementation surely will lag by several TLs.

5. Hubble. Telescope satellites are useful until the system is opened up for exploitation -- perhaps TL 8 -- after which Space Arrays can be built and placed out of orbit and in the system, or at Lagrange points, and so on.

 

[BytePro]

Wardenclyffe Tower's for terrestrial comms and power.
Gravitic powered by microwave beams for terrestrial, orbital and in-system surveillance and military comms.

 

[Vladika]

Moving a few feet doesn't matter if it's omnidirectional communications. It can swing at the end of a single tether, or be tethered at each end. Even for locator beacons, it wouldn't make much difference unless you're targeting weapons or the people are too dumb *not* to follow the GPS when it says to turn down the railroad tracks.

It does matter for navigation. Also, it's going to move kilometers, not a few few. Think of a basic helium balloon you buy for a kid on a 6 foot string. Now think of that string as 10s of kilometers...

The coverage will be limited, but not as limited as towers, and would require lower transmitter power than going to satellites.

Coverage range would be greater. Stability just isn't there though. For omnidirectional communication, no problem. Again, for navigation, it isn't going to work.

As for recharge, you could conceivably recharge it from the atmo, or run a line up to it. You *would* want to pull it down once in a while to maintain it, though - leaving you with a hole in your coverage.

The line, or lines, used to tether the thing will weight a massive amount and I doubt that there is any material that would ever be both light and strong enough to withstand the weather forces on the system and, even using hydrogen in the bag, be able to be supported.

As for recharge? The helium, or hydrogen, isn't going to just put itself in the bag. Another hose/tether to add to weight? Or, how to get the hydrogen out of the atmosphere? Carry it's own power plant, accumulate water and electrolyze it?

Mostly, airships would be useful to extend the range of communications temporarily (like a disaster that takes out the permanent towers), or perhaps in an exploratory mission. (You could have an airship above your expedition, relaying to satellites and to base camp, as you moved along.) They would work especially well in an ATU without contragrav, or if you take the tack that the only "gravitics" that works in a gravity well is contragrav (meaning you would still need another sort of propulsion to do station-keeping with that atmospheric contragrav comm platform).

Airships, not tethered...temporarily...emergency... All true (for communications)

(You could have an airship above your expedition, relaying to satellites and to base camp, as you moved along.)

We're back to satellites again? If so, why this thread? Why use an airship relay?

Now I'm just a guy with a degree in civil engineering, specializing in structures, so my opinions are probably worthless. Assuming I did learn anything at all though, this just isn't going to work. Unless, of course, there is someone out there with a degree in Handwavium or Applied Phlebotinum and actual experience in using it this manner?

Also ready and cheap access to Unobtainium?

OK I relent, it is after all Traveller...

 

[PFVA63]

Hi,

Although I'm not familiar with any references in canon regarding whether satellites exist or not, there doesn't really seem to me to be any reason why they wouldn't.

From everything posted so far, satellites seem to offer a fairly (relatively) inexpensive way to perform certain functions such as weather tracking, GPS, comms and other such stuff.

While it may be possible to instead replace a satellite with some sort of autonomous grav vehicle, I would think that cost wise replacing every satellite with such a craft would seem to likely be more expensive than instead using a small number of grav vehicles to place low cost unmanned satellites into orbit and/or use those same grav vehicles to maintain and service the stallites as needed.

 

[CosmicGamer]

for navigation, it isn't going to work.

Stationary ground locators (the cell towers that already exist?) allow triangulating precise location and navigation.

While it may be possible to instead replace a satellite with some sort of autonomous grav vehicle, I would think that cost wise replacing every satellite with such a craft would seem to likely be more expensive than instead using a small number of grav vehicles to place low cost unmanned satellites into orbit and/or use those same grav vehicles to maintain and service the stallites as needed.

As I posted elsewhere, multiple variables could impact the use of satellites. Population and density, Rich or poor, High tech low tech, and so on. Would a small corporate mining settlement set up planet wide satellites or just make use of what the star port provides for communication. Navigation could be via a system that uses the sun, moon and stars - worked for thousands of years without tech devices to assist us.

 

[atpollard]

How do you tether that thing "Stationary"? As in "still"?

The tethered airships (actually a balloon since it is unmanned) function as really tall communications towers in locations where it is impractical to build a tower. Three lines to the ground will fix a point. Which is easier, to build a 2 km tall tower or to tether a balloon to the ground with three 2.5 km long cables?

Also, how blessed many are going to be needed?

One "cell tower" to cover a really large area, If the world is POP 3 (thousands of people) one tower might serve the entire populated region.

And, how do you recharge the lift gas?

You reel in the cable and refill it or replace the balloon. Don't loose sight of the fact that tethered balloon cell towers already exist in the real world. I simply suggest that the Mars Surveyor airships proposed by some might serve a similar function and eliminate the tether while increasing the height (and, therefore range). The technological hurdles are not insurmountable. Real satellites operate in a far harsher environment and we maintain cell towers in spite of hurricanes and lightning strikes ... it is all just part of maintenance.

How much does a sealed balloon with a metal-plastic composite envelope leak? Could we be talking about annual or even 5-year maintenance. [That is not a rhetorical question, I don't know how big of a problem leaking is.]

 

[Vladika]

Stationary ground locators (the cell towers that already exist?) allow triangulating precise location and navigation.

Fixed towers worked to a marginally satisfactory degree with LORAN. The further from towers the worse the "fix". Towers, using line of sight, will not, and can not work. (For your car, on land, it will work just fine.) NOT however at sea.

Navigation could be via a system that uses the sun, moon and stars - worked for thousands of years without tech devices to assist us.

Celestial navigation worked as well as it could, but nowhere as well as you seem to think. It also evolved over thousands of years and untold financial and scientific resources were expended. Hundreds of thousands of ships sank and hundreds to thousands still do today. There isn't a ships captain, or a Blue Water sailor anywhere that is going to agree with your position.

You NEED, and in REQUIRE, star charts, declination tables etc. They vary DAY BY DAY. You must have extensive knowledge of the heavens and higher mathematics to use them and make the necessary conversions. You have to have a good Sextant AND a chronometer accurate to a couple of seconds a year. All has to survive a hostile ocean environment. The compass, while essential, is the least of your worries. (By the way, Nathaniel Bowditch found over 3000 errors in the British Navy table, considered the very best for its time. Get a copy of Bowditch's Practical Navigator, still updated and printed to this day, and try to read and follow it.)

And, ALL of these thing are totally different for every plant in the universe. You might not even be able to see through an atmosphere like that of Venus, and Jupiter?

 

[robject]

[Celestial navigation] REQUIRE, star charts, declination tables etc. They vary DAY BY DAY. You must have extensive knowledge of the heavens and higher mathematics to use them and make the necessary conversions. You have to have a good Sextant AND a chronometer accurate to a couple of seconds a year. All has to survive a hostile ocean environment. The compass, while essential, is the least of your worries. (By the way, Nathaniel Bowditch found over 3000 errors in the British Navy table, considered the very best for its time. Get a copy of Bowditch's Practical Navigator, still updated and printed to this day, and try to read and follow it.)

And, ALL of these thing are totally different for every plant in the universe. You might not even be able to see through an atmosphere like that of Venus, and Jupiter?

So, you can use a sufficiently advanced and ruggedized computer to do efficient navigation on some worlds without satellites? I hadn't thought about that before.

 

[Vladika]

The tethered airships (actually a balloon since it is unmanned) function as really tall communications towers in locations where it is impractical to build a tower. Three lines to the ground will fix a point. Which is easier, to build a 2 km tall tower or to tether a balloon to the ground with three 2.5 km long cables?

One "cell tower" to cover a really large area, If the world is POP 3 (thousands of people) one tower might serve the entire populated region.

If you stay right under it's range, yes. Forget accurate exploration.

Three lines to the ground will fix a point. Which is easier, to build a 2 km tall tower or to tether a balloon to the ground with three 2.5 km long cables?

No, it will certainly not! Experiment yourself with a kids Mylar balloon and three guys 200 yards long of nylon fishing line. You'll see when the wind blows...

You reel in the cable and refill it or replace the balloon. Don't loose sight of the fact that tethered balloon cell towers already exist in the real world. I simply suggest that the Mars Surveyor airships proposed by some might serve a similar function and eliminate the tether while increasing the height (and, therefore range).

Omni directional cell transmission will work fine. Airships can not hold their position for navigational purposes.

The technological hurdles are not insurmountable.

OK, you graduated from a much better engineering school than I did and have vastly differing experiences.

Real satellites operate in a far harsher environment and we maintain cell towers in spite of hurricanes and lightning strikes ... it is all just part of maintenance.

Satellites are designed for a differing harsh. I'm guessing you don't work for a power company on a repair crew?

How much does a sealed balloon with a metal-plastic composite envelope leak? Could we be talking about annual or even 5-year maintenance. [That is not a rhetorical question, I don't know how big of a problem leaking is.]

Buy a Mylar balloon from a florist shop. Bring it home. See what a short time it takes to "sink" and how very little it can lift in the first place.

If, in the Traveller universe, you can lift a ship for next to nothing, Satellites are going to work better than balloons and towers. Satellites will certainly be easier, and cheaper, to maintain. They will also work better for worldwide coverage.

Without trying to offend anyone, deliberately or otherwise, until you educate yourselves in physics and engineering, your arguments are futile and pointless for purposes of a "real world" solution.

 

[Vladika]

So, you can use a sufficiently advanced and ruggedized computer to do efficient navigation on some worlds without satellites? I hadn't thought about that before.

That computer is still going to need data points to work from. You have to see a celestial body, in any weather, to navigate by. You don't have to see a GPS Satellite.

I'd be most happy to have such a computer, weatherproofed and easily rechargeable!

On top of that, a human must accurately take the measurements and input them. Garbage in = garbage out.

 

[Vladika]

Wardenclyffe Tower's for terrestrial comms and power.

They never actually worked, then or now.

 

[BytePro]

Military still uses aircraft for surveillance, tracking and comms.

Non-orbital, low altitude elements can a) maintain a relative fixed position, b) transmit/receive faster (lower latency).

The significance of that last is easily overlooked (except by gamers trying to use DirectWay and the like ). Using earth geosync to maintain the 'a)' condition, one is faced with minimum latency of around 1/4 second for a data hop. Plenty of time to get dead on a battle field. This is one of the reasons the Iridium system (LEO) is useful for military applications.

As to ocean coverage from tower based cells - no reason cells can't be floated in the oceans (ala oil rigs - which have long been there own cell towers, btw). Its just a lot less efficient than using satellites.

As to airships - they can stay up a very long time, and above most atmospheric disturbances, using air and solar generated power, not to mention isotope reactors for power. (see also, U.S. military and OTH early warning systems.)

 

[Vladika]

Military still uses aircraft for surveillance, tracking and comms.

Agreed

Non-orbital, low altitude elements can a) maintain a relative fixed position, b) transmit/receive faster (lower latency).

Not good enough to navigate from.

The significance of that last is easily overlooked (except by gamers trying to use DirectWay and the like ). Using earth geosync to maintain the 'a)' condition, one is faced with minimum latency of around 1/4 second for a data hop. Plenty of time to get dead on a battle field. This is one of the reasons the Iridium system (LEO) is useful for military applications.

There is some truth in this. It is however a localized situation, not global.

As to ocean coverage from tower based cells - no reason cells can't be floated in the oceans (ala oil rigs - which have long been there own cell towers, btw). Its just a lot less efficient than using satellites.

My supertanker will try really hard not to hit any of your thousands of ocean towers. Especially during storms when I can neither see nor hold an accurate course.

As to airships - they can stay up a very long time, and above most atmospheric disturbances, using air and solar generated power, not to mention isotope reactors for power. (see also, U.S. military and OTH early warning systems.)

They still can't hold position for accurate navigation. They don't lift a whole lot of weight either. Until you find an elemental gas with better lift properties than hydrogen.

 

[BytePro]

They never actually worked, then or now.

They were never finished. Different story entirely.

 

[CosmicGamer]

Fixed towers worked to a marginally satisfactory degree with LORAN. The further from towers the worse the "fix".

I was not talking about using the towers for direct navigation. I'm talking about a blimp, antigrav platform or anything else using the towers to determine it's position and thus it can be used to provide navigation to those that are not in an optimal position to use a tower.

Celestial navigation worked as well as it could, but nowhere as well as you seem to think. It also evolved over thousands of years and untold financial and scientific resources were expended. Hundreds of thousands of ships sank and hundreds to thousands still do today.

Somehow earthlings managed without satellite navigation until the 1960s. It did work. I never said how well. It did not work as well as it could. With more modern techniques, such as simply having an accurate watch (chronometer), accurate celestial data (T: provided by the scout service?), a good calculator, perhaps even electronic and computerized equipment instead of a sextant and thus eliminating some human error, and so on, navigation can be far from the adventure it was in the 1800s.

For Traveller, other inhabited planets don't have to reinvent satellite technology nor navigation so the thousands of years and untold financial and scientific resources expended do not have to be duplicated.

I'm not debating alternatives to satellites as in a solution that would work better. I'm brainstorming alternatives to satellites for the Traveller systems that don't have them for whatever reason; population, wealth, tech level, % water, and so on.

EDIT: While weather can deter celestial navigation, it can also interfere with satellites. Many many times a year my dish for internet, dish for TV, and car GPS says it can't find a satellite in bad weather. No system will be perfect. Is it not possible certain atmospheres would preclude not only celestial navigation but the use of satellites too?

 

[Vladika]

I'm not debating alternatives to satellites as in a solution that would work better.

I'm glad to hear that.

Is it not possible certain atmospheres would preclude not only celestial navigation but the use of satellites too?

Certainly.

 

[Timerover51]

I read about high altitude blimps that used solar panels and batteries for maneuvering and IIRC tethered blimps have been used for communication 'towers'. Combine those two and you have a VERY low orbit geostationary comm/weather/imaging network available at TL 4+ (TL 7+ for solar power station keeping vs ground tether).

[OK, I just like airships.]

I like them too, but I wonder how the cost and maintenance of a large number of airships would compare to the cost of satellites.