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"Radar is useless underwater." But sonar and detecting changes in gravity (caused by the higher density of the seamount) aren't. The seamount should have been

"Radar is useless underwater." But sonar and detecting changes in gravity (caused by the higher density of the seamount) aren't. The seamount should have been detectable.

adastra22 4y ago
There's no way you could have gotten a gravity sensor to work reliably enough in that environment. Active sonar would defeat the point of a stealth submarine.
- hilbert42 4y ago
  Is that an assumption or do you know from fact? Gravity detectors work from moving aircraft (it's a common method of deployment), so motion's no problem and can be made incredibly sensitive—sensitive enough to suit the job in hand (place one on a table and then on a book on the table and you'll easily read the difference in gravity). Moreover, seamounts are incredibly large objects and would have huge signatures and thus easy to detect. I'd suggest the real issue around this matter is that it'll be classified.
  - abecedarius 4y ago
    What's the technical term for this type of gravity detector? Do you mean a gravity gradiometer? It seems hard to steer a modern pigheaded search engine away from LIGO when you search for "gravity detector".
    - hilbert42 4y ago
      Gradiometer as here: https://www.sciencedirect.com/topics/earth-and-planetary-sciences/gravity-gradiometers https://www.sciencedirect.com/topics/earth-and-planetary-sci... We'd have difficulty in fitting LIGO in a sub methinks and seamounts are static and thus no G waves. You're right though, I should have been more specific, perhaps a more understandable description would be a mass detector or sensor. I reckon the reason we don't hear much about this subject and the reason it's likely classified is that's its primary purpose would be the detection of other subs, detecting seamounts a secondary benefit.
      - abecedarius 4y ago
        Interesting, thanks. It didn't occur to me before that there might be classified work on gravity detectors.
dragonwriter 4y ago
Sonar is a brilliant beacon identifying the subs location; other than in combat where they are already detected or desperately need a hard fix on a target now, or someplace they don’t need to be stealthy, subs aren’t using it. AFAIK, the first sub-deployed gravity gradiometers were developed for the Ohio-class ballistic missile subs and Los Angeles-class attack subs like San Francisco don’t, AFAIK, have them.

"Radar is useless underwater." But sonar and detecting changes in gravity (caused by the higher density of the seamount) aren't. The seamount should have been detectable.

adastra22 4y ago

There's no way you could have gotten a gravity sensor to work reliably enough in that environment. Active sonar would defeat the point of a stealth submarine.

hilbert42 4y ago
Is that an assumption or do you know from fact? Gravity detectors work from moving aircraft (it's a common method of deployment), so motion's no problem and can be made incredibly sensitive—sensitive enough to suit the job in hand (place one on a table and then on a book on the table and you'll easily read the difference in gravity). Moreover, seamounts are incredibly large objects and would have huge signatures and thus easy to detect. I'd suggest the real issue around this matter is that it'll be classified.
- abecedarius 4y ago
  What's the technical term for this type of gravity detector? Do you mean a gravity gradiometer? It seems hard to steer a modern pigheaded search engine away from LIGO when you search for "gravity detector".
  - hilbert42 4y ago
    Gradiometer as here: https://www.sciencedirect.com/topics/earth-and-planetary-sciences/gravity-gradiometers https://www.sciencedirect.com/topics/earth-and-planetary-sci... We'd have difficulty in fitting LIGO in a sub methinks and seamounts are static and thus no G waves. You're right though, I should have been more specific, perhaps a more understandable description would be a mass detector or sensor. I reckon the reason we don't hear much about this subject and the reason it's likely classified is that's its primary purpose would be the detection of other subs, detecting seamounts a secondary benefit.
    - abecedarius 4y ago
      Interesting, thanks. It didn't occur to me before that there might be classified work on gravity detectors.

dragonwriter 4y ago

Sonar is a brilliant beacon identifying the subs location; other than in combat where they are already detected or desperately need a hard fix on a target now, or someplace they don’t need to be stealthy, subs aren’t using it. AFAIK, the first sub-deployed gravity gradiometers were developed for the Ohio-class ballistic missile subs and Los Angeles-class attack subs like San Francisco don’t, AFAIK, have them.