Seeing stars again: Naval Academy reinstates celestial navigation

Their concern seems to be, "What if none of the electronic systems can be trusted?" That wasn't as much a concern when the sextant courses were dropped, but they are now, which is why it seems they're reinstating them.

Curiously, INS (inertial navigation system), which uses gyroscopes, is often turned to as a backup for when GPS can't be used, or is otherwise unavailable. (Many guided systems now can use INS as a backup if the GPS signal is jammed.) Most ships have this as well. Presumably this would be an adequate fallback.

That being said, if my ship were dead in the water with no electrical power, this seems like a no-brainer.

There even appears to be a patent on the idea: https://www.google.com/patents/US7706917

Once launched a Trident, using a camera, gets a fix on a single specific star. It then uses the data on that star's position to correct for any errors in its internal guidance system.

See: https://en.wikipedia.org/wiki/Trident_(missile)

First, the system would be vulnerable to many of the same problems: hacking, sabotage, and electrical failure. Second, it would likely not be as robust under less than ideal conditions in which human beings with a sextant would still be able to function (e.g., partially cloudy conditions).

Still it seems smart to keep the skill around as the GPS system can be locally jammed and in WWIII could be completely knocked out.

We're coming to the end of a golden era where RF electronic reasons used to mean significant jamming was somewhat unrealistic at an analog electronics level. In the "next big war" jamming is going to be cheap and ubiquitous on the battlefield (or for that matter, in terror attacks or whatever).

There is an interesting economic warfare aspect where a jammer drone is inherently always going to be cheaper than the antiaircraft missile or antiaircraft drone that shoots it down due to certain precision flying and targeting requirements. A jammer has to keep the right side up and not hit anything, and anti-jammer has a much more complicated task of finding, reaching, and destroying a jammer. So it being cheaper to jam than to unjam means only the wealthiest aggressors with good logistics support will be able to decide when GPS will be usable on a battlefield. Also unjaming has certain risks... sure go ahead shoot down that jammer drone, the site that launches a missile or even a drone will get plastered about one minute later by what amounts to counterbattery artillery fire. Now you have GPS data but no anti-aircraft cover... hmm, probably not a good trade. This is before meta level games are played where you want to lure someone into an ambush by jamming the heck out of everything but one heavily armed and prepared "empty" mountain pass. In the future I think you can pretty much count on GPS not being available or at least not being reliable on the battlefield, and when the enemy does let you use GPS they're probably messing with you.

The concept of drones being cheaper than what it takes to shoot them down has a meta problem first discussed in anti-star-wars technology in the 80s where MIRV ICBMs had decoys... You can expect X drones of which only Y contain expensive jammer hardware, making the cost ratio of anti-jammer drones even worse compared to jammer and decoy drones.

There's two things that make GPS trickier to jam:

- it's spread spectrum with relatively hign coding gain. The signal itself is pretty much imperceptible above the noise floor until you phase lock onto the signal and despread. A really effective jammer would likely need to send out a similar but corrupted signal, not just noise.

- we know where the signal will be coming from. First that it will be coming from the sky, and once we have a copy of the almanac, we've got a pretty good idea where in the sky each SV will be. Directional antennas could further mitigate the jamming.

You're not wrong about it being jammable, but it's not trivially simple.

p.s. (because kb sucks) While the spreading codes for the civilian signal are commonly available and could be replicated in a jammer, the military spreading codes are not available. A well-funded adversary might be able to get ahold of them anyway, but it'd take some effort/treason.

Commissioned officers are responsible for the boat and the crew. That doesn't mean that they do all the work, but they are responsible for making sure it's done correctly and getting it done correctly if the crew can't. They are also responsible for training the crew to the highest standards.

Source: spent two years at the Naval Academy and one tour on a nuclear submarine during the summer.

Looks like they won't even get a sextant out of its box

[1] "Hold Fast: Stories of maniac sailors, anarchist castaways, and the voyage of the S/V Pestilence..." https://vimeo.com/15351476

There's some controversy there too as to whether it should be left in the syllabus. Personally I think it's a nice thing to do, there's something very pleasing about producing a fix especially when you do fun things like producing a running fix from sun and moon sights.

Do you think that the USNA admissions process and or the Academy's graduation requirements do not provide an equivalent filter?