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Education The Military Science

Naval Academy Reinstates Teaching of Celestial Navigation 350

HughPickens.com writes: At the US Naval Academy in Annapolis, midshipmen studied celestial navigation for more than a century -- until 1998, after a decision that came after months of discussion that began with a 1996 curriculum review. Midshipmen were relieved. Celestial calculations were painfully difficult, requiring a nautical almanac and volumes of tables. Now Tim Prudente reports at the Capital Gazette that the Navy has reinstated the teaching of celestial navigation in the manual issued two months ago. The first midshipmen to receive training were juniors during this past summer school. Future classes will learn theories of celestial navigation during an advanced navigation course. And the Class of 2017 will be the first to graduate with the reinstated instruction.

But is there really any point in knowing how to navigate by the stars in a world of GPS? "In the event that we had to go into a national emergency, we would probably have to shut the GPS down because it can be used by potential enemies," says retired Navy Capt. Terry Carraway. "We went away from celestial navigation because computers are great," says Lt. Cmdr. Ryan Rogers, the deputy chairman of the academy's department of seamanship and navigation. "The problem is, there's no backup."
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Naval Academy Reinstates Teaching of Celestial Navigation

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  • Why wouldn't the military just turn their encryption keys back on so that they can use it but others get worse data? I do agree that teaching your officers celestial navigation is important, but when shit hits the fan, it will be interesting to see which ones actually retain it and can use it without constant practice.
    • by Anonymous Coward on Saturday October 17, 2015 @07:15PM (#50751257)

      Why wouldn't the military just turn their encryption keys back on so that they can use it but others get worse data? I do agree that teaching your officers celestial navigation is important, but when shit hits the fan, it will be interesting to see which ones actually retain it and can use it without constant practice.

      They're not doing this in case they have to turn off the GPS. They're doing this because they realize that the enemy may be able to turn off the GPS (along with everything else that relies on modern microelectronics).

      • They're not doing this in case they have to turn off the GPS.

        No?

        "we would probably have to shut the GPS down" -Navy Capt. Terry Carraway

    • by OzPeter ( 195038 )

      Why wouldn't the military just turn their encryption keys back on so that they can use it but others get worse data?

      What if there are no satellites to turn the key back on for? The Chinese for one are known to have anti-satellite weapons.

      • by aliquis ( 678370 )

        The Chinese for one are known to have anti-satellite weapons.

        US shot down the Solwind P78-1 satellite with an ASM-135 ASAT launched from an F-15 already back in 13th September 1985.

        "It's not rocket-science nowadays."

        • Re:Turn key back on? (Score:4, Interesting)

          by Somebody Is Using My ( 985418 ) on Sunday October 18, 2015 @12:39AM (#50752193) Homepage

          Mind you, there's a significant difference between hitting a satellite orbiting at slightly more than 300 miles up, and hitting one that's 11,000 miles up.

          A lot of the low-earth orbit satellites - which includes some reconnaissance satellites - are vulnerable to common fighter-launched ASATs, but hitting something in geosynchronous orbit is a bit more difficult. It would take large ground-based rockets to reach that altitude, and you would have to launch at least six to disrupt the GPS system over a particular area (and even then, the results would be only temporary as the network can compensate for some losses). Even ICBMs aren't powerful enough to reach them; you would need liquid-fueled rockets that need to be fueled up prior to launch (you don't just keep that stuff sitting around in the rocket's gas tank indefinitely) prior to launch, so your preparations would be very visible and very vulnerable. GPS satellites are also traveling at more than 10,000mph, which makes them a tricky target to hit, so you'll likely need to launch more than one rocket per satellite to ensure a successful interception.

          It's not impossible but it is difficult and probably more costly in resources than it is worth.

        • by kybred ( 795293 )

          GPS satellites orbit at 12,500 miles. I don't think a jet launched missile would be able to reach them.

          • A quick google shows that the angular resolution of an adaptive optics telescope is about 1e-5 degrees, which translates roughly to 4 meters at that altitude. You see where I'm going with this?

    • by tlhIngan ( 30335 )

      Why wouldn't the military just turn their encryption keys back on so that they can use it but others get worse data?

      Uh, the P-code is already encrypted. Selective Availability was turned off only on the C/A (Coarse Acquisition) code.

      Civilian GPS usage is C/A only. Military uses the C/A and P code.

      In fact, to use the P-code, you must already lock onto the C/A code to get rough positioning. You cannot acquire the P-code directly.

  • I wonder how much this can be automated. Seriously, I bet it's fairly easy to program a software that takes a picture at night or of the sun and guess where you are.

    • by gman003 ( 1693318 ) on Saturday October 17, 2015 @07:31PM (#50751321)

      It's been done - some nuclear missiles had star-based navigation systems for mid-course corrections, as did the SR-71.

      However, it's still a good idea to have people who can do it manually, because anything that will take out GPS has a good chance of taking out your computers as well. It doesn't even have to be a common thing - a dozen people on a ship crewed by five thousand is enough.

      • I would imagine that a small subset of it still taught in SERE school as well - finding your way at night when you are ERE'ing would be rather helpful, and it is almost guaranteed that you wouldn't have a GPS... or sextant, piles of charts, etc

      • by KGIII ( 973947 )

        I think it started in the late 40s - well, the idea and tech. A quick(ish) check on Wikipedia has some cryptic information about the Snark. The Snark used astro-inertial guidance and is the earliest one that I know of and was able to find. According to Wikipedia, the project started in 1946 though I doubt the tech was quite ready at the time for the accuracy desired. Consider, also, at that time we were okay with bombing large areas and it wasn't until later, in Khrushchev's reign, that both sides of the Co

      • Airliners and military aircraft up until the 1960s or so had sextant domes so the navigator could shoot stars during flights over the ocean. That was the only way back then.
    • by Irate Engineer ( 2814313 ) on Saturday October 17, 2015 @07:39PM (#50751349)

      On a pitching, rocking ship in the middle of the sea, with a sky that may have cloud coverage so you don't have much choice in the stars that you can shoot? A picture of the sky tells you very little - you need the angle of the celestial object relative to the local horizon. A good human navigator might be able to shoot a few stars through a hole in 9/10ths cloud coverage and get a fix.

      Star-trackers work well in space because the platform is relatively stable and you don't have any clouds (usually). Apollo 13 had problems with its star tracker after the explosion because of a cloud of reflective debris around the ship. They had to do a manual burn sighting the Earth's terminator through the reticle.

      Not saying a computer couldn't be designed to do it, but getting a robust cel-nav system for sea vessels that can handle the noisy environment that is the sea and sky will be a challenge. Humans still beat computers in some things, this is one of them.

      • by Shinobi ( 19308 )

        Yeah, knowing the usual commenting on how easy it should be, because can do it, those geeks would probably implement it so that it'd require a 90% match of a clear sky, would be incapable of dealing with clouds, water or ice on the lens and all other such things that are a pain in the ass.

        Plenty of young people going into the military nowadays think that it's pointless to learn how to read a map or how to use a compass. Then they whine about how unfair it is when they are sent on an excercise where GPS is

        • The thing that ought to amuse all of us is that they believe the GPS is trustworthy. I've spent a road trip getting regular laughs from looking at where the GPS thought I was--it was utterly convinced that it was in a boat or perhaps a submarine. I had no idea my car at the time was so capable!

          The worst part of this is that even your average modern GPS unit will do this to you. One of the things I will do when utterly bored is check to see where my phone thinks it is, which hasn't failed yet to be quite

      • by PPH ( 736903 )

        The cloud coverage is a valid point. But the rocking ship isn't that big a deal. With a sextant, you are trying to measure the elevation of a celestial body above the horizon. Both images are moving in unison relative to the ship so it's not that difficult to bring the star to the horizon. It is easy to do unless the rocking is so bad you can't keep the star in your field of view.

        • by Shinobi ( 19308 )

          Don't forget water or ice on the lens etc

        • But a lot of ships don't simply rock to and fro, especially when seas are bad. They pitch, roll, heave, and gyrate in all sorts of weird ways. And the angle is worthless if it isn't down to the nearest horizon (i.e. if your sextant is slightly tilted it is a bad sight). You need to orient quickly to local vertical and stay there, so you would need an inertial system to find the gravitational acceleration vector - on a frame that is pitching and bucking and accelerating in all sorts of crazy ways.

          And we also

      • by tomhath ( 637240 )

        Gosh, what did sailors do for thousands of years when all they had was a sextant?

        Learning how to navigate starts with understanding how and why a sextant works.

      • by nehumanuscrede ( 624750 ) on Saturday October 17, 2015 @09:38PM (#50751753)

        Allow me to introduce you to the ships gyro. Also referred to as a stable element.

        It's the reference plane the fire control systems utilize while plotting a firing solution for the ships guns.

        Some of the older manned directors also referenced them and kept the director perfectly stable even in rough seas. Was the best place to be in the event you and the pitching seas didn't get along :)

      • by mysidia ( 191772 )

        On a pitching, rocking ship in the middle of the sea, with a sky that may have cloud coverage so you don't have much choice in the stars that you can shoot?

        Why not leave the visual range, and use passive microwave, UV, IR, and radio wave sensors?

        The clouds mostly block visible light, but there is a much broader spectrum of particle emissions from the sun to earth than the naked eye can perceive.

    • There's probably an app for that.

  • by rmdingler ( 1955220 ) on Saturday October 17, 2015 @07:17PM (#50751269) Journal

    But is there really any point in knowing how to navigate by the stars in a world of GPS? "In the event that we had to go into a national emergency...

    National emergency?

    Just my 2 cents, but you should have to train a dog to mind you before you have a child, and you should be able to navigate by the stars prior to being allowed to use the GPS.

  • Even if they didn't shut down GPS in a conflict it's ridiculously easy to jam by the enemy and highly susceptible to EM disturbance if nukes are involved.

  • by blindseer ( 891256 ) <blindseer@@@earthlink...net> on Saturday October 17, 2015 @07:38PM (#50751345)

    If the federal government keeps slicing away at our capability for space flight then at some point we might see Navstar GPS fail merely due to lack of maintenance. Ground based radio navigation has been losing support due to the success of Navstar and other GPS systems. Having the US military rely on foreign built navigation systems just sounds like an easy way for an enemy to add confusion in a battle.

    The nice thing about ground based radio navigation is that they are easy to maintain, no need for a rocket that can reach orbit. The bad thing about them is that they make easy targets. So if a nation can figure out how to take out Navstar then they can handicap the US military. In the absence of GPS and radio navigation beacons one would hope we'd still have enough people smart enough and knowledgeable enough to find other means to navigate.

    This doesn't necessarily mean celestial navigation is the answer but that is probably one of the most reliable and accurate means we have available outside of GPS. Any radio transmitter can be used as a radio navigation beacon, just so long as you know where that transmitter is located, and enough smarts to operate a radio. In fact radio transmitters were used in WWII as beacons for pilots flying from California to Hawaii. Normally radio silence was practiced on the islands so that the Japanese couldn't use them as a navigation aid either but getting bombers safely to the air base was seen as a priority, and therefore an exception to the rule.

    Using a commercial radio station as a navigation beacon did several things for the US in WWII. The radio station already existed, so no additional cost for the military. If you are going to transmit something then it may as well transmit music that is soothing to the flight crews as well as the general public. It also didn't broadcast that flights from the US mainland was underway, only that radio silence was lifted for some reason which could mean a lot of things. In modern times, during a real war, I expect creative aids to navigation to pop up like this. However, this isn't the 1940's. Any potential enemy we have today is going to have the technology to take out radio transmissions with greater ease than the Japanese Imperial Navy.

  • Ship GPS can go out (Score:5, Interesting)

    by danbuter ( 2019760 ) on Saturday October 17, 2015 @07:43PM (#50751361)
    On the 1991 cruise I was on when in the Navy, our ship's GPS went out. No way to fix it. We had to use compasses and star charts till we got to Pearl Harbor so it could be fixed. If the guys hadn't been trained for it, we'd have been screwed.
    • Exactly (Score:5, Insightful)

      by Etherwalk ( 681268 ) on Saturday October 17, 2015 @08:04PM (#50751443)

      On the 1991 cruise I was on when in the Navy, our ship's GPS went out. No way to fix it. We had to use compasses and star charts till we got to Pearl Harbor so it could be fixed. If the guys hadn't been trained for it, we'd have been screwed.

      Exactly. Tech can fail or be disabled, either deliberately or due to enemy action. Remember how Russia was testing their GPS jamming tech against the US a few years ago in the middle east, by providing it to one of the countries we fought? Similarly, Iran used GPS to bring down a drone. Our guys need to be able to get by without it and, for that matter, to confirm that the computer is right.

      It's not like we're requiring every enlisted man to know this stuff--but the officers on a ship of war should damn well know how to navigate by the stars if they have to.

    • by KGIII ( 973947 )

      Or you could have just used the radio and someone would have found you eventually. I don't think you'd have been screwed so much as annoyed and not doing a whole lot. It's not like there were pirates, German submarines, or Japanese battleships. What kind of ship where you on that wasn't part of group? I'm no expert or anything but I bet they'd have noticed you went missing and come to find you.

    • Having talked to people that were on US Navy ships at about that time I was told that a common means of navigation was by land based radio navigation. One person described to me a rather large antenna array on the bow of the ship that could give the direction of a radio beacon. I was told that normally this was folded down so as to not interfere with the weapons but in a case of a need to get somewhere quickly they'd prop it up so they can get an accurate location and heading.

      Knowing what I do about radio

    • In 1981 I sailed a small boat across the Atlantic (30' cat, took 22 days). GPS (civilian) did not exist [1996 was when it became useful and accurate], we used the sun, tables, and a sextant. I only shot the sun, not stars. Sight reduction is tedious, but not too bad with tables and perhaps a calculator. I used an HP41c - wonderful gadget.
      Even with a calculator, it is not especially quick, and what you get is a position line (LOP) [actually a large circle mapped onto the earth surface corresponding to a cons

  • Reasons for knowing (Score:4, Informative)

    by CanadianMacFan ( 1900244 ) on Saturday October 17, 2015 @08:39PM (#50751569)

    First off you should never completely trust your computers. What happens if a software bug or a hardware problem occurs and says your 10 nautical miles west from where you really are? Not likely but still always good to check to make sure that your systems are running correctly.

    The other reason is what if something happens to your ship and you have to abandon it before a distress call could be sent. Quite possible in times of war. You would want to know how to locate where you are so you could paddle the raft in the right direction (if you had a map or knew the location of land) or had some form of communication.

    • What happens if a software bug or a hardware problem occurs and says your 10 nautical miles west from where you really are?

      Well, after your other two redundant systems flag the bad one, you just mark it for maintenance when you get back to shore.

      still always good to check to make sure that your systems are running correctly.

      That's great advice if there's absolutely no cost to the time and effort being wasted. Otherwise, it's pretty foolish.

      It's pretty damn easy to check that GPS is working... Check that e

  • The SR-71 had astro internal navigation [wikipedia.org] long before GPS. This system required quite a bit of calibration at pre-flight, but with the sensors we have available today (gyros, accelerometers), this could easily be added to ships. This system can work day or night as well. It is pretty ingenious. There are several commercially available versions which could easily be incorporated into ships or drones. CelNav is a great exercise in math, but if your ship gets hit with an EMP, knowing your location won't do

  • Decades ago, I worked in the TACAMO [wikipedia.org] aircraft, the older KC-130 version. TACAMO was a US Navy aircraft charged with maintaining communications with nuclear submarines in the event of nuclear war. The aircraft had a small "sunroof" and it's sole purpose was to allow the navigator to see the sun and stars so he could use the sextant that was part of the issued equipment. The idea was that there would be no radio navigation aids left when their mission was over and they had to return to ... well anywhere the
  • by Morpeth ( 577066 ) on Saturday October 17, 2015 @09:18PM (#50751711)

    As an avid backpacker, I'm amazed how often recent enthusiasts I've come across have little or zero/map and compass skills. Sure, your GPS on your iPhone and hiking app are great, IF you have power, and if it's accurate. But if you lose it, break it, battery dies, then what?

    I still travel with Trails Illustrated maps (or other topo maps) and a compass whenever I'm in the backcountry.

    I think the Naval Academy made the right decision.

  • "In the event that we had to go into a national emergency, we would probably have to shut the GPS down because it can be used by potential enemies," says retired Navy Capt. Terry Carraway."

    When the shit hits the fan against a capable enemy ( cough. . . China . . . cough ) the first thing they're going to do is target all satellites considered military assets. GPS, Sigint and recon systems will be the first to go down.

    If you, or your weapons, rely too heavily on such things, the War will be a very short one

  • by softcoder ( 252233 ) on Saturday October 17, 2015 @10:24PM (#50751889)

    When I was learning Celestial Navigation, there were two sets of 'Almanacs' we had to use. One was the Nautical Almanac which gave the positions of the stars, the Sun and the Moon for each minute of each day of the year. These were issued every year by some National Observatory. The other set was just a cookbook of spherical trigonometry. Obviously you can program any modern calculator with the appropriate trig formulas so the Midshipmen would not have to waste time looking up those numbers in the books. I am pretty sure that with modern memory you could put the entire almanac for the year on a USB stick, and so you would not need to look up those numbers either. Add the two together and you can have a rugged, solar powered device that can do the calculations for you. Now all you need to do is get out your sextant and clock, take the sights, plug in the time, the readings and the corrections, and let the pocket calculator do the grunt work.
    pgmer6809

  • by Ronin Developer ( 67677 ) on Saturday October 17, 2015 @11:37PM (#50752033)

    Celestial navigation was taught in our Naval Science Navigation course. As naval bridge officers, we were required to learn celestial navigation primarily as tradition and to have a working understanding of the mechanics of the process. That being said, one must know where the ship is at all times. Today, we rely on GPS, inertial navigation systems and the gyroscopic compass (as opposed to a magnetic compass). There have been times when we lost GPS or LORAN C while at sea. We did experience loss of the gyroscopic compass in the middle of ocean and our ship didn't have INS. You have a mission to carry out and that entails safely navigating your vessel.

    Basic skills such as dead reckoning and visual position fixes are used when near land. At sea, with no landmarks, knowing where you is just as important. Case in point is that there is an underwater mountain in the Pacific that ships still manage to hit. Avoiding those things is pretty important. Murphy's law will ensure that your ship fill find the underwater mountain or shoal waters if you aren't prepared.

    Do navigators take celestial fixes every night the skies are clear? No. They do it from time to time to keep the traditions alive. And, should the skills ever be needed, they will have them. The calculations are tedius and no where as accurate as GPS fix. But, it's an interesting exercise and a time honored tradition.

  • My mostly ignorant opinion manually filling out forms and digging thru sight reduction tables is a pointless exercise.

    I think a backup for GPS is worthwhile but all people really need is some experience using a sextant and reasonable ability to quickly spot nav stars and input measurements into a computer. Alternatly use a star nav system that will automatically and accurately compute your position based on image capture of the sky.

    No matter what you'll still need an accurate clock to get a fix so there is

    • by mysidia ( 191772 )

      input measurements into a computer.

      Computers break or become unavailable due to loss of power, moisture ingress, or due to being hit with an EMP

      Computers are also not very effective for navigating life rafts, when there are no batteries to power the computer.

    • by AHuxley ( 892839 )
      It depends on who and how smart the enemy is. Can they do a lot of anti-satellite missile above the area of interest? Got a fifth column or special forces in surrounding nations?
      The next big worry for most modern navy planners is what is carried deep into the modern ship in terms of consumer grade crew electronics.
      Was the ship designed to be some clean intranet where every internal computer command is considered as quickly as possible with less consideration on origin and security? Is the ship 'running
  • Military GPS accuracy = 0.001 nm (a few yards).
    Inertial accuracy = 0.1 nm / hour degradation
    Celestial navigation accuracy = hundred nm
    So unless GPS is gone for days, inertial is still better
    That's a result of USA getting rid of LORAN which before GPS was the primary update source for inertial systems, and after GPS was fully operational switched to backup.
    Celestial navigation is pretty much strictly a means to getting to the nearest port. Very limited usage for combat operations.

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