3 ms·

Use a magnometer on a winged drone? Presumably filter out high frequency magnetics due to motor noise? Or hang manometer?

bboygravity 3y ago
Ok, I'll do it. Give money.
- jvm___ 3y ago
  We combed the desert
  - a_gnostic 3y ago
    We ain't found sh¡t!
    - vundercind 3y ago
      Spaceball to Starfleet officer was a really weird career progression for Tuvok.
      - arp242 3y ago
        https://www.youtube.com/watch?v=UQ7TnQBSV00 https://www.youtube.com/watch?v=UQ7TnQBSV00
tlarkworthy 3y ago
that's how they do them for real. Only with a helicopter and pilot, but still, with a big magnet and sensors hanging underneath.
- xvector 3y ago
  Interesting! I think this (and large-scale searches in general) is one area where a drone is probably much more likely to work than a helicopter/pilot, simply because of the sheer area to cover.
  - defrost 3y ago
    Interestingly the data has largely already been acquired globally since the 1950's using fixed wing aircraft, helicopters in places like PNG, and human pilots. Drones took a bit long to arrive. Eg. Australia has already been covered with multi instrument surveys (nine channel magnetics, 256 channel radiometrics, microwave radar DTM, etc.) with 27 million line-kilometres of survey data gridding the country. https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search#/metadata/70282 https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search#/me... https://www.ga.gov.au/about/projects/resources/awags https://www.ga.gov.au/about/projects/resources/awags Australian, South African, Russian, Canadian companies and pilots have been jobbing on this work about the globe for decades, in the USofA the USGS and DoE have been surveying internally during the same 70 year period.
    - deleted 3y ago
      [deleted]
    - greggsy 3y ago
      What is the primary purpose of these endeavours? Mineral detection, space safety, radio stability, or just general scientific “because we can (and probably should)”?
      - defrost 3y ago
        Mineral and energy exploration, either broad area (an entire country or significant part) or more detailed closely spaced examination of specific areas. Such surveys are funded by large companies wanting to extend their exploration data, mid size companies wanting to firm up infomation on a prospect, and national governments | world bank projects that are looking to promote exploration and development in greenfield locations.
defrost 3y ago
You can fly over the same spot in four different directions and get four different readings. You can fly over the same spot at four different times of day and get four different readings. You also really want nine magnetometers, one for each X,Y,Z axis and repeated on each wingtip and tail boom. If you're going to filter like a professional you need a base station to record the diurnal flux and subtract that in post, you also need to fly calibration clover leafs in a magnetically level wide area and develop a Kalman filter to subract heading generated flux. There's also the active magnetism compensation caused by the aircraft and its components, such as engine accessories, engine masses, avionics, current generated on the fuselage and other factors. If you're running a small fleet of aircraft to cover a million line kilometers or are otherwise pooling results into a standard magnetic map collection each aircraft will need to have its signature influence removed. If you're mapping entire countries over decades then, of course, everything needs to be levelled against the changing IGRF (Internatinal Geomagnetic Reference Field), or the other one (there's another standard global magnetic reference field). Then there's the question of just how small an iron rich rock you could reasonably get a blip from.
- davidmurdoch 3y ago
  Sounds pretty straight forward then!
  - defrost 3y ago
    Boringly routine, at 70 m/s you can get 100,000 km of line data recorded in just under 40 full ten hour days. Add on a few days for calibration, sorting out airstrips and fuel supplies and you're sorted. Next contract please. Of course that leaves the post processing . . .
- regularfry 3y ago
  I would be somewhat shocked if this was a difficult problem for submarine detection aircraft. It's almost exactly what they're built for. https://en.wikipedia.org/wiki/Lockheed_P-3_Orion https://en.wikipedia.org/wiki/Lockheed_P-3_Orion is what comes to mind, but that's 1960's tech.

bboygravity 3y ago

Ok, I'll do it. Give money.

jvm___ 3y ago
We combed the desert
- a_gnostic 3y ago
  We ain't found sh¡t!
  - vundercind 3y ago
    Spaceball to Starfleet officer was a really weird career progression for Tuvok.
    - arp242 3y ago
      https://www.youtube.com/watch?v=UQ7TnQBSV00 https://www.youtube.com/watch?v=UQ7TnQBSV00

tlarkworthy 3y ago

that's how they do them for real. Only with a helicopter and pilot, but still, with a big magnet and sensors hanging underneath.

xvector 3y ago
Interesting! I think this (and large-scale searches in general) is one area where a drone is probably much more likely to work than a helicopter/pilot, simply because of the sheer area to cover.
- defrost 3y ago
  Interestingly the data has largely already been acquired globally since the 1950's using fixed wing aircraft, helicopters in places like PNG, and human pilots. Drones took a bit long to arrive. Eg. Australia has already been covered with multi instrument surveys (nine channel magnetics, 256 channel radiometrics, microwave radar DTM, etc.) with 27 million line-kilometres of survey data gridding the country. https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search#/metadata/70282 https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search#/me... https://www.ga.gov.au/about/projects/resources/awags https://www.ga.gov.au/about/projects/resources/awags Australian, South African, Russian, Canadian companies and pilots have been jobbing on this work about the globe for decades, in the USofA the USGS and DoE have been surveying internally during the same 70 year period.
  - deleted 3y ago
    [deleted]
  - greggsy 3y ago
    What is the primary purpose of these endeavours? Mineral detection, space safety, radio stability, or just general scientific “because we can (and probably should)”?
    - defrost 3y ago
      Mineral and energy exploration, either broad area (an entire country or significant part) or more detailed closely spaced examination of specific areas. Such surveys are funded by large companies wanting to extend their exploration data, mid size companies wanting to firm up infomation on a prospect, and national governments | world bank projects that are looking to promote exploration and development in greenfield locations.

defrost 3y ago

You can fly over the same spot in four different directions and get four different readings. You can fly over the same spot at four different times of day and get four different readings. You also really want nine magnetometers, one for each X,Y,Z axis and repeated on each wingtip and tail boom. If you're going to filter like a professional you need a base station to record the diurnal flux and subtract that in post, you also need to fly calibration clover leafs in a magnetically level wide area and develop a Kalman filter to subract heading generated flux. There's also the active magnetism compensation caused by the aircraft and its components, such as engine accessories, engine masses, avionics, current generated on the fuselage and other factors. If you're running a small fleet of aircraft to cover a million line kilometers or are otherwise pooling results into a standard magnetic map collection each aircraft will need to have its signature influence removed. If you're mapping entire countries over decades then, of course, everything needs to be levelled against the changing IGRF (Internatinal Geomagnetic Reference Field), or the other one (there's another standard global magnetic reference field). Then there's the question of just how small an iron rich rock you could reasonably get a blip from.

davidmurdoch 3y ago
Sounds pretty straight forward then!
- defrost 3y ago
  Boringly routine, at 70 m/s you can get 100,000 km of line data recorded in just under 40 full ten hour days. Add on a few days for calibration, sorting out airstrips and fuel supplies and you're sorted. Next contract please. Of course that leaves the post processing . . .
regularfry 3y ago
I would be somewhat shocked if this was a difficult problem for submarine detection aircraft. It's almost exactly what they're built for. https://en.wikipedia.org/wiki/Lockheed_P-3_Orion https://en.wikipedia.org/wiki/Lockheed_P-3_Orion is what comes to mind, but that's 1960's tech.