4 ms·
How would it navigate? GLONASS signals won't penetrate the water to the depths mentioned. The 1.6 and 1.2 Ghz bands it uses won't even go through 1 meter of sea
by chiph 5y ago
How would it navigate? GLONASS signals won't penetrate the water to the depths mentioned. The 1.6 and 1.2 Ghz bands it uses won't even go through 1 meter of seawater [0] A star tracker would also be worthless. An inertial reference might be "good enough", as in "close enough for nuclear war"
[0] https://www.researchgate.net/figure/Radio-wave-attenuation-by-sea-water-as-a-function-of-thickness_fig3_340683649 https://www.researchgate.net/figure/Radio-wave-attenuation-b...
- RobertMiller 5y agoInstead of thinking of this like a missile, instead think of it like a submarine. Submarines don't use star tracking, they use inertial navigation systems to inform dead reckoning. This accumulates error over time, but my impression is they work a lot better than you might expect.
- chemeng 5y agoYou also don't need perfect accuracy for something that is a weapon of last resort with a 1km blast radius and 500,000 km^2 fallout radius.
- chiph 5y ago> Instead of thinking of this like a missile, instead think of it like a submarine I'm former Air Force, so that sort of comes with the territory. Sorry. :)
- SkittyDog 5y agoThis is very much a solved problem, for several decades now. US and Russian naval submarines routinely patrol for thousands of miles over weeks or months, without surfacing. https://en.m.wikipedia.org/wiki/Submarine_navigation https://en.m.wikipedia.org/wiki/Submarine_navigation It's not mentioned in the article, but I believe US subs also have a long-tether communications buoy that can float to the surface, but not expose itself vertically, to communicate with satellites. I would be surprised if it did not also have a GPS antenna.