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The US military is working on a device that can use stars to determine location even during the day.

buildbot 3y ago
Couldn’t that be just celestial navigation with a very specific notch filter for starlight wavelengths? So you can see stars in daylight?
- K0balt 3y ago
  Basically, ultra high dynamic range.
- mnw21cam 3y ago
  Stars are broadband light sources, there isn't a specific starlight wavelength. Likewise, the Raleigh scattering in the atmosphere is largely a broadband source of light, since it is a reflection of our sun's light. You might get some slight benefit by looking at the redder end of the spectrum, but the improvement won't be massive. However, stars are (to the nearest approximation) point sources. If you use a telescope and zoom in to the star, then you can spread the atmosphere brightness over a large area while concentrating the starlight into a very small area, which means you can see stars during the day. Couple that with a reasonable level of high dynamic range sensor and integration over time, and it would be quite possible to observe the positions of a load of stars during the day.
tivert 3y ago
> The US military is working on a device that can use stars to determine location even during the day. They already developed a device that could do that in the 60s, but it was quite large: https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Astro-inertial_navigation_system https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Astro... https://timeandnavigation.si.edu/multimedia-asset/nortronics-nas-14v2-astroinertial-navigation-system https://timeandnavigation.si.edu/multimedia-asset/nortronics... Do you have a source for the one you say they're working on? Is more portable or hand-held?
- HyperSane 3y ago
  https://www.popularmechanics.com/military/research/a36078957/celestial-navigation/ https://www.popularmechanics.com/military/research/a36078957... https://insidegnss.com/the-stars-return-draper-patents-celestial-navigation-system/ https://insidegnss.com/the-stars-return-draper-patents-celes...

Couldn’t that be just celestial navigation with a very specific notch filter for starlight wavelengths? So you can see stars in daylight?

K0balt 3y ago
Basically, ultra high dynamic range.
mnw21cam 3y ago
Stars are broadband light sources, there isn't a specific starlight wavelength. Likewise, the Raleigh scattering in the atmosphere is largely a broadband source of light, since it is a reflection of our sun's light. You might get some slight benefit by looking at the redder end of the spectrum, but the improvement won't be massive. However, stars are (to the nearest approximation) point sources. If you use a telescope and zoom in to the star, then you can spread the atmosphere brightness over a large area while concentrating the starlight into a very small area, which means you can see stars during the day. Couple that with a reasonable level of high dynamic range sensor and integration over time, and it would be quite possible to observe the positions of a load of stars during the day.

tivert 3y ago

> The US military is working on a device that can use stars to determine location even during the day. They already developed a device that could do that in the 60s, but it was quite large: https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Astro-inertial_navigation_system https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Astro... https://timeandnavigation.si.edu/multimedia-asset/nortronics-nas-14v2-astroinertial-navigation-system https://timeandnavigation.si.edu/multimedia-asset/nortronics... Do you have a source for the one you say they're working on? Is more portable or hand-held?

HyperSane 3y ago
https://www.popularmechanics.com/military/research/a36078957/celestial-navigation/ https://www.popularmechanics.com/military/research/a36078957... https://insidegnss.com/the-stars-return-draper-patents-celestial-navigation-system/ https://insidegnss.com/the-stars-return-draper-patents-celes...