3 ms·
Sodern launches Astradia, a star tracker for GNSS-denied navigation
- blacklion 1y agoSo, technology closed the circle. Nice.
- ck45 1y agoThose systems are not new, the SR-71 used the same principle, see e.g. https://www.iancollmceachern.com/single-post/unveiling-the-secrets-of-the-sr-71-blackbird-astro-nav-system https://www.iancollmceachern.com/single-post/unveiling-the-s...
- blacklion 1y agoIt is exactly what I mean. That "early" (cold war era and maybe later) spy planes, strategic bombers, cruise missiles and even ICBMs used stars to navigate. And, oh, yes, all ships before last century, too, of course. So it is more spiral than circle :)
- defrost 1y agoand post WWII landrovers, the ships of the desert, pre GPS, used star fixes to layout grid roads for the world's largest test range*. https://www.beadelltours.com.au/lb_survey.html https://www.beadelltours.com.au/lb_survey.html * "the largest land-based test range in the western world" https://en.wikipedia.org/wiki/RAAF_Woomera_Range_Complex https://en.wikipedia.org/wiki/RAAF_Woomera_Range_Complex
- nickspacek 1y agoNeat, this latest implementation seems a little more compact than the SR-71's, but it's hard to tell. https://timeandnavigation.si.edu/multimedia-asset/nortronics-nas-14v2-astroinertial-navigation-system https://timeandnavigation.si.edu/multimedia-asset/nortronics...
- AStonesThrow 1y agoWow! A daytime star tracker! What wavelengths does it use?
- stogot 1y agoThe e day part surprised me. I was familiar with other systems that use stars in darkness (very high altitude)
- rich_sasha 1y agoPerhaps it uses just the one star, the Sun, at daytime+clouds. You can get a surprising amount of precision just from that (but not the stated 1m per 70km travel, surely). And it's easy to spot, maybe even under heavy cloud cover. On clear sky, you can often see Venus and Sirius with naked eye, so surely easier still with a precise instrument.
- sorenjan 1y ago> not the stated 1m per 70km travel, surely I don't think that's what they claim. They write "tracking capacity to within a few arc-seconds, equivalent to 1 meter at a distance of 70 km.", so I interpret that as a way of visualizing how small of an angle a few arc-seconds is. This provides an absolute navigation reference, so a relative error after a certain distance traveled doesn't make sense either. The final navigation system would use inertial navigation combined with this.
- throw0101b 1y ago> Perhaps it uses just the one star, the Sun, at daytime+clouds. For marine celestial navigation, there are fifty-eight stars that are regularly used / have been standardized on: * https://en.wikipedia.org/wiki/List_of_stars_for_navigation https://en.wikipedia.org/wiki/List_of_stars_for_navigation With electronics it may be possible to see more than with the naked eye ("Mark One Eyeball"), and have a larger 'almanac' with digital storage than is practical with paper. As a side note: using only one star and the Sun would give you two lines of position, and they would potentially intersect at two locations, so if you don't have any estimate of your position you don't necessarily know where you are between the two: * https://en.jeandusud.com/two-equations-for-celestial-navigation/ https://en.jeandusud.com/two-equations-for-celestial-navigat... If you do have some idea, then you'd pick the intersection which is closest.
- voxadam 1y agoEnglish: https://sodern.com/en/astradia-a-daytime-star-tracker-for-a-reliable-and-robust-navigation-system/ https://sodern.com/en/astradia-a-daytime-star-tracker-for-a-...
- sorenjan 1y agoThat's strange, I submitted the english version but I see it has been changed to the french.
- voxadam 1y agoIt's just a guess, but I'm willing to bet HN mangled the URL you submitted and set it to the URL specified by the hreflang="x-default" header. Now that I think about it, I'm pretty sure I've had the exact same thing happen in the past on a story I submitted.
- consumer451 1y agoI am pretty that sure HN automatically reads the canonical tag on a page, and changes the link to that. In this case, that was: <link rel="canonical" href="https://sodern.com/fr/astradia-le-viseur-detoiles-diurne-pour-un-systeme-de-navigation-sur-et-robuste/" /> It should be noted that the submitter has a couple minutes after posting to change the link and title back to what they want via [edit].
- perihelions 1y agoI wonder if it'd make sense these days to put optical navigation beacons in space. This OP solution relies on inertial navigation, because, the star-tracking part is only a reference for orientation in space, which is an incomplete coordinate set. But if you were to put *artificial* stars close to Earth, you'd gain an additional parallax measurement, and obtain a complete basis.
- sneak 1y agoHow would they be powered to be bright enough to be visible? If you switched to parts of the EM spectrum where you don’t need high power output, you’re back at radio waves and you’ve simply reinvented GPS.
- wongarsu 1y agoReally bright geostationary satellites to reflect sunlight might work. At geostationary they should be far enough out that you always have line of sight to one that isn't in earth's shadow. You'd need to specifically design them to have a huge surface area to get enough brightness. Maybe that'd make them impractical
- perihelions 1y agoOptical isn't particularly power-inefficient, is it? The equivalent of an optical magnitude +5 star, in 500 km low orbit, is (if I didn't err) only 1 kilowatt of isotropic power in a solar spectrum. Much less if it's a non-isotropic beam pointed towards earth. +5 is the brightest ~1,600 stars, likely similar to whatever any star tracker would be using.
- sneak 1y ago24kWh daily is a lot of energy. For reference, the current GPS satellites are 1000kg and transmit with 50W (1.2kWh daily). Here on the ground, for rough calculations, 50kWh is around 450kg in batteries alone. There might be lighter chemistries but this is just to get you in the ballpark. I think a 1kW light on 24/7 in orbit would need to be a very large vehicle (2-4x the size of the current Navstar satellites) with huge batteries and gigantic solar arrays. Falcon 9 can probably do it, FH definitely can. An RTG might work but those are out of fashion near Earth these days for obvious reasons. In any case it would be quite costly (you’d need lots) and its resistance to jamming would benefit your adversaries just as much as it would benefit you. Not to mention, the astronomers would hate you.
- contingencies 1y agoUse case = ? 3kg! That's a very high price to pay for reliability under GNSS denied environments in the day time. Surely you can get ~altitude from a barometer, ~position from inertial + IMU + prior position, and if you want more accuracy maybe DEM models + topography is better. Therefore I'd suggest this is not going to be very useful on anything with a view toward efficiency (drones). This is more likely a 'quick fix' plugin for existing fat-plane avionics for 'identified risk' reasons. OK move commercially, but technically meh. The go to market plan would presumably be FUD around GNSS denied situations. Reality: unlikely to be problematic in most cases (known flight path, high altitude, low GNSS-denied environment dwell time).
- shellfishgene 1y agoAlso a bit pricey at 250k Eur...
- throw0101d 1y ago> Also a bit pricey at 250k Eur... That's the annual salary of of 2-3 airline pilots, which you pay year after year in OpEx. This is a one-time CapEx that will work for years and may allow you to fly (i.e., generate revenue) when otherwise you would be grounded: * https://www.cbc.ca/news/world/gps-interference-airlines-1.7213538 https://www.cbc.ca/news/world/gps-interference-airlines-1.72...
- constantcrying 1y agoIn a scenario where you have a conflict with completely denied GNSS (e.g. mass destruction of satellites) the applications are basically limitless. 3kg is perfectly viable on anything which isn't a small drone. Aircraft, ships, tanks, APCs, etc. all can use them.
- contingencies 1y agoGood use case. Although, they said the design is for planes. This is significant because the optics probably assume uninterrupted sky view with no interceding light sources which is an invalid assumption at ground level. If setting off a flare or cycling street lights is all it takes to deny positioning it's a weak terrestrial solution.
- throw0101b 1y agoSomeone is working on restoring an astro tracker from a B-52 bomber: * Part 1: https://www.youtube.com/watch?v=nkvN74wuT8w https://www.youtube.com/watch?v=nkvN74wuT8w * https://www.youtube.com/playlist?list=PL-_93BVApb5_Gufx3xFN9qW__mL4BUsy2 https://www.youtube.com/playlist?list=PL-_93BVApb5_Gufx3xFN9... * https://www.glennsmuseum.com/items/b52_astro/ https://www.glennsmuseum.com/items/b52_astro/
- deleted 1y ago[deleted]
- aredox 1y agoIs there a similar system but much more affordable? I don't need it to be space-ready or milspec-grade or even compact, I was just thinking of something for tinkerers. (The translation used by Sodern, "Star Tracker", gets me only camera gimbals to take astrophotography pictures) Edit: found some leads around the cubesat community. Still to see if it works from the ground or in daytime. https://ieeexplore.ieee.org/document/9179736 https://ieeexplore.ieee.org/document/9179736 https://openstartracker.org/ https://openstartracker.org/
- throw0101b 1y agoI'm curious to know why resurrecting (e)Loran seems to be a hard sell: * https://en.wikipedia.org/wiki/Loran-C https://en.wikipedia.org/wiki/Loran-C China built out a GNSS backup with it: * https://www.gpsworld.com/china-completes-national-eloran-network/ https://www.gpsworld.com/china-completes-national-eloran-net... * https://rntfnd.org/2024/10/03/china-completes-national-eloran-network-the-paper/ https://rntfnd.org/2024/10/03/china-completes-national-elora... * https://www.mdpi.com/2076-3417/13/23/12703 https://www.mdpi.com/2076-3417/13/23/12703 And there's been some rumblings from Korea and UK: * https://www.gpsworld.com/south-korea-partners-with-broadcaster-on-eloran-and-10-cm-gps/ https://www.gpsworld.com/south-korea-partners-with-broadcast... * https://www.gpsworld.com/uk-leading-the-west-in-pnt-with-clocks-eloran-and-quantum-research/ https://www.gpsworld.com/uk-leading-the-west-in-pnt-with-clo... but no major moves in most countries, even though there's a recognition of GPS/GNSS vulnerabilities by even the (US) military: * https://fedtechmagazine.com/article/2022/05/dod-transportation-consider-backups-vulnerable-gps https://fedtechmagazine.com/article/2022/05/dod-transportati...
- sorenjan 1y agoThere's BPS (Broadcast Positioning System) too. https://www.nab.org/bps/ https://www.nab.org/bps/
- relaxing 1y agoBecause despite what they say the signals can still be jammed. Also your transmitters are massive targets for kinetic fires.
- throw0101d 1y agoOf course any signal can be jammed if you throw enough watts out, but Loran is five millions times stronger: * https://www.militaryaerospace.com/rf-analog/article/14181490/eloran-loran-c-gps-gnss https://www.militaryaerospace.com/rf-analog/article/14181490... And even if your ground transmitters can be taken out, it's a lot easier to build some new Loran transmission gear and radio towers than it is to launch new GNSS satellites (which are also vulnerable to attack).
- voxleone 1y agoI'm working on an open-source system called SpinStep (just search GitHub) — it's a quaternion-driven traversal framework for orientation-based logic and spatial data structures. It’s not directly tied to geolocation, but it could integrate nicely with something like Astradia. Since Astradia provides high-fidelity attitude data without relying on GNSS, SpinStep could use that orientation stream to drive autonomous behavior trees, scanning patterns, or state transitions — all without depending on coordinates or maps. Basically: orientation in, logic out. Would love to hear from others thinking about orientation-first autonomy or mapless navigation.
- throw0101d 1y agoFrom four months ago, "Celestial Navigation for Drones": * https://news.ycombinator.com/item?id=42767797 https://news.ycombinator.com/item?id=42767797
- hollerith 1y agoThis could help North Korea and Iran develop ICBMs.
- Havoc 1y agoUS had this tech 50+ years ago (sr71) so would think it’s within reach of most state actors now even without help
- Havoc 1y agoLet’s hope they stick it on the airliners flying in the baltics