5 ms·
Magnetometers based on diamonds will make navigation easier
- mc32 6y agoIf this is basically comparing readings to a map of the Earth's magnetic field, couldn’t they use lidar and a lidar topo map? (I think cruise missiles used some type of map for navigation too).
- vardump 6y agoLidar's range is measured in hundreds of meters. That might be a bit limiting for flight. Radar could be used, but you might not want to have a "hey all, I'm here!"-beacon for military purposes. You could of course use cameras, pointing either up (stellar navigation) or down, but that's not going to work all the time.
- meatmanek 6y agoA lot of overlap, but some other details in this Air Force press release from May: https://afresearchlab.com/news/air-force-investigates-using-quantum-materials-in-new-navigation-tool/ https://afresearchlab.com/news/air-force-investigates-using-...
- maddyboo 6y ago> And, crucially for military applications (and unlike GPS-based systems), it is unjammable by the enemy. Is it entirely infeasible for an adversary to disrupt the local magnetic field enough to interfere with the readings?
- amerine 6y agoBased purely in my layman understanding of magnetism, you’d need quite a disturbance and that same energy would likely not make the rest of any electronics happy.
- throwaway0a5e 6y agoAlso give away your position.
- whatshisface 6y agoA static magnetic field would not influence nearby electronics.
- Whirl 6y agoThey could using a small EMP weapon. These happen to have short range and are explosively pumped, so at that point it’s easier to just disrupt the magnetometer by initiating rapid explosive disassembly.
- contravariant 6y agoField strength pretty quickly drops of over distance, and even the most powerful magnets don't go much beyond 100T (and even that's a stretch). Assuming you could somehow achieve 100T 1m away from the magnet (which is charitable, usually the high teslas are only achieved at the exact centre) then just a kilometre away it will have dropped to 1 microtesla, well below the 25~65 microtesla of the Earths gravitational field. So you'd need those kinds of magnets on a kilometre spaced grid, which doesn't seem realistic. And that's with some rather charitable assumptions about building a strong magnet, to be honest I expect you'd have difficulty turning a few compasses in the same building, let alone miles away.
- chockablock 6y agoThe AFRL press release linked in another comment says that this technique relies on measurement of the crustal magnetic field, which is in the 10s of nanoteslas range.
- kurthr 6y agoIt depends on how far away they are. Magnetic (dipole) fields fall as the cube of distance. Since the earth's pole has a dipole moment (8.0 * 1022 Am^2) and is detectable ~30uT at the earth's radius, thousands of km from the core. Even a 1T field at a radius of 1m would be billion times smaller ~1nT a km away or 1/30k of the earth's field. A giant 6T MRI would be comparable to earth's field at 27m.
- eximius 6y ago> so accurate that it might supersede GPS for aerial navigation Very cool! I wonder if: 1. the device can be made small enough for consumer use (i.e., phones, smart watches, etc) 2. how much data it needs to pinpoint its location. i.e., it might be suitable in aviation because it can collect a larger amount of data by virtue of... you know... goin' fast.
- twarge 6y ago1. No, anyway, your phone would have to be engineered to be non-magnetic to the same level that you wish to make measurements. 2. Yes, faster is better. Flying lower is also more specific if you have a sufficiently good magnetic map.
- civil_engineer 6y agoSo there may be a use for diamonds beyond industrial cutting.
- exabrial 6y agohttps://archive.is/5zdJw https://archive.is/5zdJw
- twarge 6y agoMagnetic navigation is totally real and seems to work great. Diamond magnetometers might not be a great fit for this application. They require a powerful laser, RF, and are presently huge and impractical. Also, they are just terrible at accuracy and drift like crazy. Finally - and this is the thing I really can't get - they require a giant magnetic field to operate. If your magnetometer has a giant magnet bolted to it, you would expect it to basically measure drift in that magnet. Diamond magnetometer people will jump out of the woodwork now, but I haven't seen published high quality data that says otherwise. Would love to be proved wrong. Diamond magnetometers are great at being a magnetic microscope since they have really high density of measurement sites and you can stick it right up next to an object of interest.
- bb88 6y agoMuch of that is answered in the article.
- 082349872349872 6y agoDrifting like crazy might not be such an issue if one is looking for an AC signal, such as could be produced by 130m x 13m metal objects moving against the stationary background. Huge and impractical sounds like SQuIDs might still be preferable. LN2 is a byproduct, so it's cheap.
- mehrdadn 6y agoHow do compasses work on aircraft? Don't the (varying across space/time?) magnetic fields from everything on the aircraft overwhelm whatever tiny variation there is from Earth's surface?
- intc 6y agoIn aircrafts it's common to use navigation instruments based on gyroscopes. See: * https://en.wikipedia.org/wiki/Gyroscope https://en.wikipedia.org/wiki/Gyroscope * https://www.experimentalaircraft.info/articles/aircraft-gyroscopic-principles.php https://www.experimentalaircraft.info/articles/aircraft-gyro...
- mehrdadn 6y agoThanks but I'm confused, how is that relevant to the article?
- kjeetgill 6y agoYou asked > How do compasses work on aircraft? So the parent responded with gyroscope based navigation. Perhaps you'd meant to ask > How would these compasses work on an aircraft? *Edited
- mehrdadn 6y agoI.. guess? Didn't even occur to me... I thought it went without saying that my comment wasn't just blatantly irrelevant to the article, but maybe I shouldn't have assumed that.
- pezezin 6y agoA compass and a gyroscope are two very different devices. The former measures the Earth magnetic field, which is an external magnitude independent of your craft or movement. The later measures your rate of rotation, which is an internal magnitude. Even the best gyro will have an small amount of noise and drift, so you need some external reference to periodically correct it. Also, because they measure an speed, to get your orientation you need to integrate the measures over time, which amplifies the noise. In reality you usually combine both with an accelerometer and a GPS.
- bb88 6y ago> And, crucially for military applications (and unlike GPS-based systems), it is unjammable by the enemy. So while there is not such thing as a magnetic laser, there is a laser that can create a strong magnetic field. https://physicsworld.com/a/radiation-friction-could-make-huge-magnetic-fields-with-lasers/#:~:text=Huge%20magnetic%20fields%20can%20be,role%20in%20generating%20the%20field https://physicsworld.com/a/radiation-friction-could-make-hug....
- qserasera 6y ago> Our calculations suggest that at least a power of several petawatts is needed Good to know
- Animats 6y agoHow stable is the earth's magnetic field at that level of detail? There's enough movement of the magnetic poles right now that new compass correction charts have to be issued every year or so. Will you need to constantly update your magnetic maps?
- renox 6y agoI cannot help but remember the time when I got lost during scuba diving because my new torch was metallic enough that my compass gave bad direction..