Allow me, before I go into my idea, to explain the basis behind it.
It’s expensive to put objects into space, as a result, the objects we put into space need to be very expensive (because they need to be very heavily developed). I believe it’s on the order of ten thousand dollars per pound lifted into orbit, and on top of that you have to pay to design an object that can fold up onto a launch vehicle, open successfully and maintain an orbit.
Then, if that object does break down, it’s stuck in orbit (potentially contributing to Kessler Syndrome), generally making Earth Orbit potentially less safe with every launched object. Objects in space are also subject Solar Flares, which while rare can cause serious damage to electronics – this risk made worse by the fact that the equipment itself is extremely expensive.
So, my idea, and please tell me if it’s at all viable is… (drumroll please…)
Rather than equipping Satellites with GPS (for example), wouldn’t it be simpler long term to implement something similar to the Zephyr (Wiki Link), a long-term UAV.
With a large fleet of these, we could implement more advanced technologies quicker (it’s easier to retrofit a small plane than it is a satellite, and it’s also easier to retire a plane than satellite).
So my thoughts of the downsides:
[li]Investments into GPS over the last few decades have been immense (counterpoint: many of the GPS satellites are ending their expected life spans).[/li][li]Cost – it seems like this could cost more, long term, than Satellite implementation (counterpoint: it also allows the faster movement of technology, which may offset that cost?).[/li][li]Cost for extremely rural areas may be prohibitive (as in, who’s going to pay for a fleet half as large as the one covering the continental US to cover Alaska? For that matter, who’s going to pay for – or maintain – the one that is going to have to cover the Pacific and Atlantic? (Counterpoint, it’ll put current, and older, aircraft carriers to an economically productive use – although they still wouldn’t come near paying for themselves.)[/li][/ol]
Okay, so tell me why my idea isn’t viable, or what changes would have to be made for this to be a realistic proposal? I understand that we’d have to write new software for the UAV’s themselves (and maybe even replace the entire GPS system), as well as “protecting” airspace for them at certain altitudes to prevent Commercial Aircraft incidents.
There would be complications, but I can’t imagine it’d be considerably more complicated than the original set up of the GPS system. You could use a few fixed points on the ground as reference (for the UAV), then a few UAVs as reference for the end user system.
I’m not a GPS expert by any means, but isn’t the object to have a receiver triangulate based on fixed points? If you’re trying to get a fixed point from three airplanes flying around in circles, it seems to me that’s going to be near impossible.
GPS satellites aren’t fixed - they orbit the Earth in approximately 12 hours. They move in a predictable way, so it’s possible to know their precise position at a specified time.
And receivers don’t triangulate - they compute time difference between the arrival of signals from pairs of satellites, which places them on a hyperbolic locus. Where hyperbolas (or more properly, hyperbloids of rotation) intersect is the receiver’s position.
With current solar and battery technology, solar-powered vehicles can barely handle themselves. The payload of the system you gave is 5 pounds. All the electrical energy is being used to keep the aircraft aloft, with none to spare to be a transmitter. I think we’d have to have a much greater capability in solar generation and storage for a satellite-equivelant UAV to be practical.
I’m not an expert either, but my understanding is that they provide location based on a set of fixed points, on Earth. By measuring the distance to those points, and carefully cataloging the trajectories of the satellites themselves (and accounting for General Relativity) you can extrapolate your location based on the Satellite’s location using the time delay between when a signal is sent, and when it’s received.
In theory, the only change needed would be that instead of measuring the first and second set of distances on the scale of Orbit, it would be on the scale of high atmospheric flight.
So let’s alter that to High Altitude Lighter than Air Vehicles (HALTAV)?
Warning, Link contains bad-internet practices (a popup, and screen-takeover which closing gives permission to open a link behind the current window).
I’m glad I’m not the first to think of it, thank you for providing the link Dewey.
Now that I’m thinking about it, Haltav would be a better design anyway, fewer parts could go wrong and therefore easier maintenance (probably) and less expense (most likely).
So what’s the highest payload we could reasonably put in a haltav? Could we put a hundred pounds on one? Could we put enough of them in the air, cheaply enough to replace Satellites? I assume that 1 haltav wouldn’t be able to replace 1 satellite, but could a dozen? If so, it would give us a chance to replace older tech more frequently… and possibly open up more spectrums to public use, if we find a way to use less spectrum space (although right now according to wikipedia GPS systems use 1.57542 GHz and 1.2276 GHz, and those seem pretty specific).
I don’t see how that could possibly work.
The reason it works with satellites is they have predictable orbits that are relatively stable, and not subject to the whims of weather. How are you going to keep a vehicle in the atmosphere positioned within a few feet indefinitely?
Why would it need to be positioned in one spot indefinitely?
Satellites certainly aren’t, and while they’re predictable because of defined trajectories, it’s not difficult to locate a lighter than air vehicle using radio signals.
Think of it like this: Right now, when you turn on your GPS is references your location against the satellites, and the satellites locations against the map of where those satellites are. (overly simplified, of course.)
In my scenario, it would work like this: You turn on your GPS and it references your location against the HALTAVs, who reference their location against fixed points on Earth (for instance, the Empire State Building, Times Square and Central Park).
Errors due to wind? What errors due to wind? As far as I was aware, wind did not interfere with radio signals.
A LORAN type system would work, although since it’s discontinued there wouldn’t be a reason to use that system over another type of system. LORAN, LORAN-C & CHAYKA are certainly a proof of concept that you can locate things based on Geographical waypoints.
I don’t see any way to have an aircraft fly in a sufficiently accurate path. Also, you would need to replace all the existing GPS receivers in the world, so there’s another, more practical, reason why it won’t work.
You speak of deployment of new technologies, but communications satellites haven’t really changed all that much from the 1960s. There just isn’t a need to deploy new technologies for them: Signal goes up, signal comes down. The satellite need not know nor care what those signals mean.
This idea is not feasible for the answers already listed, i.e. the lack of a precisely known geodetic location. The position of GPS satellites, once calibrated in its on-orbit station, is known to within a fraction of a meter relative to World Geodetic System 1984 (WGS84). It would not be possible to hold any airship in so precise a location, and in order to have global coverage would require several hundred thousand of these devices, and you’d also have to have some very complex cellular identification scheme to prevent the signals from interfering with each other. This is all for ground GPS navigation; for aircraft flying up above at >30kft they would receive a large number of direct line signals. I suppose you could somehow mathematically dither all of those signals to obtain some kind of positional fix, but it would be a mess.
A comparison to fixed, ground-based systems like LORAN-C isn’t really apt. Even if it were, LORAN-C and similar systems are nowhere near as accurate, suffer from a variety of atmospheric effects, and require far more energy than GPS satellites that transmit in the microwave frequency versus the longwave LORAN.
There is a further thing to consider; support of the GPS system provides a very needed demand for both domestic heavy lift space vehicles and spacecraft design and processing. Depending on your point of view, this is either “maintaining a ‘warm line’ industrial base of engineering and manufacturing capability” or “corporate welfare for the aerospace industry”, but either way without this the only other regular user of such systems are government reconnaissance satellites, and from a purely commercial standpoint the average citizen is getting far more value from GPS. Without this regular use, many astronomical, exploratory, or climatological programs performed by NASA would be prohibitively expensive, and the benefits derived therefrom–including early warning of weather and natural hazards, space monitoring of pollution effects, and pure research science for future unforeseen benefit–would be lost.
Well, that’s not quite true; satellites have changed pretty dramatically from the 'Sixties. From the actual physical hardware, robustness, reliability, operational life, et cetera to bandwidth and overall data throughput using a variety of multiplexing technologies, new satellites are far more advanced than the first primitive satellites. The comparison between a Ford Model A and a Nissan GT-R is nothing compared to the differences between Telstar 1 and an Iridium satellite.
But it is true that communication standards and protocols evolve more slowly than satellite systems age out, and in the era of purely digitally-modulated signals, upgrading a satellite is often just a matter of uploading a firmware patch and performing a warm recycle; no manual intervention or physical replacement required.
I think the HALTAVs could be made to work technically, if you had enough of them that they could each see several of their nearest neighbors. Instead of the satellites knowing where they are due to the predictability of their orbits, the HALTAVs could continuously triangulate their positions relative to each other and to fixed points on the ground. Once their positions are known, you could use the same algorithm for a HALTAV-based GPS.
You might even be able to use existing GPS receivers. The HALTAVs could transmit an “ephemeris” for an orbit that matches their location and velocity at the time of transmission. This would of course vary much more rapidly than that for a true orbit.
The lower their altitude, though, the more you’d need to get coverage over the same area as satellites give.
I think the biggest downside is that the funding for GPS satellites comes from the military, and you’d need to find some other source. HALTAVs would be useless over hostile territory, since they’d be easily shot down. And as long as the GPS satellites are there, HALTAVs are redundant, and you’re not going to get that funding.
The Aircraft doesn’t have to fly in a sufficiently accurate path, though. The Aircrafts position would be constantly referenced against known, fixed points on the ground, and then your GPS device would be constantly referenced against that aircraft.
The biggest (logistical) problem I can see with this is oceanic deployment.
Yes, the GPS units would have to be replaced. That would be prohibitively expensive if it had to be done all at once, but a phased change wouldn’t necessarily be.
Other technologies have been discontinued for a better tech, so if a better tech could be found it’d eventually replace GPS.
I know, that’s why I’m speaking of new technologies. Commsats haven’t changed, but technology has.
There’s not a need to deploy new technologies now, but we’re currently on a continuous basis redeploying old technologies. My question is – if it’s not free to maintain the old technologies, why not look into investing in newer technologies that could (potentially) lead to better, safer, long term results?
What I’m suggesting is that we phase out support for legacy tech if it can be proven that newer tech is more effective (and, if you read later on in this post economics does come into play).
Assume, for a moment, that is an issue that can be solved – I think it can, especially in modern nations (Yes, the Military wouldn’t be able to use GPS in combat operation in unmapped areas, which is a downside).
I’m still not sure why the HALTAV’s have to be perfectly stationary. A HALTAV with a method of locomotion (maybe a propellor, depending on altitude), solar panel and coordinate system would (probably) be able to maintain a stable position within a few square miles – using ground based (known, fixed) waypoints it would be able to measure its position within its box and the position of something else on the ground.
There was no comparison to LORAN-C. LORAN-C was proof of concept that you could locate something on Earth, using a standardized system. Implementing a LORAN-C like system to keep track of the HALTAV’s, and then using the HALTAV’s as the deployment platform for GPS transceivers.
This would be the biggest concern to me, frankly, and something I hadn’t thought about. Your other objections, I think, are either a result of a miscommunication on my part (LORAN-c), or are (relatively) minor things that can be worked around, if there’s sufficient benefit to doing so.
Some of the things could be transfered to HALTAV’s (like Geological Satellites), but quite a bit could not (like Weather Sats, and most Astronomy ones) – and the cost to put those into space, coupled with the cost of the HALTAV program could equal or exceed the current cost of those same satellites coupled with HALTAV. If that’s the case – and it may very well be, as I hadn’t considered the cost increase from lack of demand and associated lack of supply – it wouldn’t make economic sense to transition, even if it did (and I’m not sure it does, but I see the potential for it to) make technological sense.
Also, I don’t consider End-User switching (like Garmin, TomTom or any other GPS manufacturer) part of the economic cost for changing systems, if you phase out legacy technology, which almost must be done eventually, for efficiency and sanity’s sake if for no other reasons, when newer, better tech is developed.
Also, I think we’re getting hung up on the example I used in the OP – specifically, GPS. GPS was used as an example, however it is by no means the only thing (and not the first thing, frankly) that popped into my mind when HALTAV’s (or their UAV-esque counterparts) did.
My idea was actually ridiculously cheap internet. Rather than launching a satellite, which costs an boatload of cash, a poorer country could launch a hand full of HALTAVs, use a dish with a motor (like the old big ugly dishes) to constantly carry the ISP end of the signal, and then provide (or allow purchase of) relatively cheap motor-driven dishes to provide the consumer end, which would probably be cheaper than:
a) laying down miles and miles of cable (and allow for faster expandability – more HALTAVs = more bandwidth, eventually you could even program HALTAV’s to act as hubs and route packets through them… maybe?) or
b) buying/renting satellite space.
The problem is that this is a fundamental problem with your concept; without an inertial reference frame–which in the case of GPS satellites is a very precisely known on-orbit location relative to WGS84–you quite simply cannot provide location information to high precision. Absent of fixed or known time-dependence references, an aircraft only knows its speed and motion relative to the constantly moving atmosphere.
I don’t understand what you mean by " LORAN-C was proof of concept…" LORAN-C was the latest fully operational LORAN system and protocols. While some navigators still refer to the older LORAN-A time-distance references, LORAN-C was in use for three decades, although progressively supplanted by GPS. And even the GPS-SA (the original less precise dithered signals provided to commercial GPS users) were generally far more accurate than LORAN-C navigation. In fact, a precise celestial reading by an experienced sextant operator was often more accurate than LORAN (at least -A); the advantage of LORAN was full time availability (albeit over limited areas), day or night regardless of cloud cover.
Setting aside technical feasibility, even the cost of this system just to provide comparable service to commercial uses (who are currently free rides on the GPS system) is going to be enormous, probably on the same order as deploying and maintaining GPS. The cost per individual unit may be lower, but you are going to have to have many thousands of units to provide the same coverage as one GPS satellite on a pro-rata basis, and when you look at the cost in that way it is trivial to see that it doesn’t reduce your cost significantly if at all. You also have to consider that a single significant climatological event, like a hurricane or powerful storm, may immediately knock out hundreds or thousands of these UAVs in a single swath, just at a time when precise location and navigation information is desperately needed.
For real-time locating systems (RTLS) suitable for general navigational use, GPS has essentially eclipsed all other navigation beacon technologies (including those used for ) because it is cheap, easy to use, and highly precise, and I have yet to see a concept that improves upon it for general use.
Unmanned LTAV, solar powered drones and tethered balloons have all been explored for rural broadband. It may make sense for that - it would work a heck of a lot better than satellite service. Think of it as a fixed wireless tower without the mountain. It’s not “ridiculously cheap” internet. It’s a way of getting broadband to places unreachable by cable or dsl.