I'm not an electrical engineer so please forgive my ignorance. I guess I could just ask ChatGPT but figured there may be a more interesting response here. Why can't the ocean have something like GPS? Also, if a nuclear submarine (those ones whose exact positions are classified) identified the location of this submersible, would they tell the relevant authorities? Or would they not, in order to protect their classified sensors and position?
Ask HN: Why is there no GPS in the ocean?
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Re: Ask HN: Why is there no GPS in the ocean?
#2GPS works on the surface of the ocean. But the radio waves cannot penetrate water very far, so it fails if you are submerged (few things can which is why subs are so well hidden compared to aircraft.
Unless a nuclear sub was specifically sent to the area to look, it is very very unlikely to just be "in the area". Even if it were there, it is very hard to find a small metal box on the bottom of the ocean. There is no real sensor for that. Most military subs are not designed to dive beyond about 500m depth (there is no need, 100m is more than enough to be functionally undetectable from the surface). The titanic is at about 3800m. So they likely could not get anywhere near close enough.
Re: Ask HN: Why is there no GPS in the ocean?
#3The ocean can’t have GPS because GPS relies on time of flight calculations for radio waves (aka light) traveling at the speed of light through air. The ocean, to the surprise of many, is not composed of air, and is really, really, exceptionally good at scattering light. What you could have, instead, is an acoustic positioning system that would rely on fixed transponders that would allow time of swim calculations for sound waves traveling through water. This would be phenomenally problematic, as you’d need a near perfect understanding of confounding factors like salinity, temperature, depth, etc to accurately model the incoming reply… you’d also drive the whales and fishes to consider well justified total warfare against the really loud and insensitive terrestrial creatures they vastly outnumber.
Re: Ask HN: Why is there no GPS in the ocean?
#4GPS is a one way system. A GPS receiver can only tell where it is, it does not transmit its position. To transmit position you would use a EPIRB. A EPIRB however cannot work underwater as its radio signal would be blocked by the water just as a GPS signal is blocked.
They are looking for this submersible by sonar. You don't need a nuclear submarine for sonar as it can done with ships ,sonobuoys dropped by aircraft or RV subs with sonar.
Re: Ask HN: Why is there no GPS in the ocean?
#5Adding some points: Radio waves (very high frequency) of GPS cannot go deep in the ocean. Very low frequency can, but their wavelenght is very big, so unsuitable for a GPS.
The only ways to "see" undersea are acoustic and magnetic.
Nuclear sub navigation rely on inertial systems, and i think they can give a position to civilians for rescue.
Re: Ask HN: Why is there no GPS in the ocean?
#6GPS is a one way system. A GPS receiver can only tell where it is, it does not transmit its position. To transmit position you would use a EPIRB. A EPIRB however cannot work underwater as its radio signal would be blocked by the water just as a GPS signal is blocked. They are looking for this submersible by sonar. You don't need a nuclear submarine for sonar as it can done with ships ,sonobuoys dropped by aircraft or…
These are all good answers by the way thank you. Isn't there like an "emergency transponder beacon" or something (like aircraft have?) that ships and submersibles must have? Why can't this be used?
Re: Ask HN: Why is there no GPS in the ocean?
#7GPS is a one way system. A GPS receiver can only tell where it is, it does not transmit its position. To transmit position you would use a EPIRB. A EPIRB however cannot work underwater as its radio signal would be blocked by the water just as a GPS signal is blocked. They are looking for this submersible by sonar. You don't need a nuclear submarine for sonar as it can done with ships ,sonobuoys dropped by aircraft or…
These are all good answers by the way thank you. Isn't there like an "emergency transponder beacon" or something (like aircraft have?) that ships and submersibles must have? Why can't this be used?
That’s what the EPIRB is… problem is it has to reach the surface to broadcast; they’re designed for finding floating vessels / life boats, not submerged objects (in this case, tombs). To be useful it would need to be spooled out on a VERY long line that you could follow back down. In this case that means the EPIRB would need to be buoyant enough to float both itself and 4000+ meters of heavy line … which would be great, although also a threat to navigation.
Re: Ask HN: Why is there no GPS in the ocean?
#8Earlier quoted context omitted.
These are all good answers by the way thank you. Isn't there like an "emergency transponder beacon" or something (like aircraft have?) that ships and submersibles must have? Why can't this be used?
That’s what the EPIRB is… problem is it has to reach the surface to broadcast; they’re designed for finding floating vessels / life boats, not submerged objects (in this case, tombs). To be useful it would need to be spooled out on a VERY long line that you could follow back down. In this case that means the EPIRB would need to be buoyant enough to float both itself and 4000+ meters of heavy line … which would be gre…
Isn't there a way to use the charge conductivity of water to send a signal--like "electrolysis radio"? Alternately it seems a constellation of cheap radio beacons / high powered IR reflectors, that can float to the surface at a constant rate in event of emergency. So you basically end up with a 2D surface trail of reflectors laid over time since the incident. That should be somewhat helpful to pin down a search area, I would imagine, without relying on a single one, or having a long spool line. But I don't know for sure, just spitballing. Those poor people :(
Re: Ask HN: Why is there no GPS in the ocean?
#9Earlier quoted context omitted.
That’s what the EPIRB is… problem is it has to reach the surface to broadcast; they’re designed for finding floating vessels / life boats, not submerged objects (in this case, tombs). To be useful it would need to be spooled out on a VERY long line that you could follow back down. In this case that means the EPIRB would need to be buoyant enough to float both itself and 4000+ meters of heavy line … which would be gre…
Isn't there a way to use the charge conductivity of water to send a signal--like "electrolysis radio"? Alternately it seems a constellation of cheap radio beacons / high powered IR reflectors, that can float to the surface at a constant rate in event of emergency. So you basically end up with a 2D surface trail of reflectors laid over time since the incident. That should be somewhat helpful to pin down a search area,…
People have been spitballing on this problem for generations, and that latter one’s been tried too… problem is it’s effectively the same thing as trying to pinpoint a diver by her bubbles; if she’s near the surface, works great… if she’s 4KM down then the bubbles hit the surface spread effectively randomly over hundreds and hundreds of square kilometers, and usually kilometers off horizontally.
The best way to maintain communication with a submersible is a tether. The best way to know the position of a submersible is a tether. The best way to raise a submersible in trouble is a tether… this company chose to go another way. And, let’s be clear, even if they knew precisely where it was the odds are very good that they couldn’t possibly effect a rescue.
The grim truth is that everyone aboard is already dead, the hope is that it was a sudden implosion rather than slowly freezing, drowning, or asphyxiating.
Re: Ask HN: Why is there no GPS in the ocean?
#10Earlier quoted context omitted.
Isn't there a way to use the charge conductivity of water to send a signal--like "electrolysis radio"? Alternately it seems a constellation of cheap radio beacons / high powered IR reflectors, that can float to the surface at a constant rate in event of emergency. So you basically end up with a 2D surface trail of reflectors laid over time since the incident. That should be somewhat helpful to pin down a search area,…
People have been spitballing on this problem for generations, and that latter one’s been tried too… problem is it’s effectively the same thing as trying to pinpoint a diver by her bubbles; if she’s near the surface, works great… if she’s 4KM down then the bubbles hit the surface spread effectively randomly over hundreds and hundreds of square kilometers, and usually kilometers off horizontally. The best way to mainta…
You were right man! Tragic. I'm hoping you're a navy insider and can feed us interesting tidbits about UFOs. Any stories? Do you know how the Navy detected the anomaly? Was a ship nearby or was it their monitoring grid? It's good they informed everyone--I had a feeling they definitely knew what happened or would be the ones who would find it.