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Space

A Simple Streetlight Hack Could Protect Astronomy From Urban Light Pollution (space.com) 160

Posted by BeauHD from the growing-threat-to-astronomy dept.
Tereza Pultarova reports via Space.com: Light pollution is a growing threat to astronomy, but a new streetlamp technology could restore clear views of the night sky. [...] A study published earlier this year found that stars are disappearing from the sky at an average rate of 10% per year. This trend affects even the world's most remote observatories. Germany-based startup StealthTransit recently tested a solution to this growing issue. "Unfortunately, this problem haunts almost all observatories today," Vlad Pashkovsky, StealthTransit's founder and CEO, told Space.com in an email. "Modern telescopes are highly sensitive and feel the impact of outdoor lighting of cities located at the distance of 50 or even 200 kilometers [30 to 120 miles]. This means that virtually every observatory on Earth either already needs, or will need in the future 10 years, protection from the light of large cities."

StealthTransit's solution relies on three components: A simple device that makes LED lights flicker at a very high frequency that is imperceptible to the human eye, a GPS receiver, and a specially designed shutter on the telescope's camera that can blink in sync with the LED lights. The GPS technology guides the telescope's shutter to open only during the fleeting moments when the LED lights are switched off. The experiments, conducted at an observatory in the Caucasus Mountains in Russia, showed that the technology, dubbed the DarkSkyProtector, could reduce unwanted sky glow in astronomical images by 94%. "We can say that the telescope was seeing almost a dark sky at this time," Pashkovsky said. "The important thing about our technology is that it makes all kinds of lights astronomy-friendly, including outdoor advertising and indoor lighting in apartments, offices and stores."

The technology could filter out lights from nearby towns and villages as well as those surrounding the observatory itself. It might sound impractical to refit an entire town with devices that allow lamps to blink, but Pashkovsky said that most existing LED lights can operate in the blinking mode and that new lamps designed specifically with sky protection in mind would be no costlier than existing LED technology. The most expensive element of the DarkSkyProtector system is the telescope shutter, which needs to be lightweight and agile enough to blink about 150 times per second. StealthTransit tested the prototype shutter on a 24-inch-wide (60 centimeters) telescope and hopes to make the technology available for larger telescopes. Although StealthTransit's technology is not yet ready for commercial use, Pashkovsky said, the firm hopes to have a product fit for the world's best telescopes in five to seven years.
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A Simple Streetlight Hack Could Protect Astronomy From Urban Light Pollution More

A Simple Streetlight Hack Could Protect Astronomy From Urban Light Pollution

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  • car headlights (Score:3)

    by stooo ( 2202012 ) on Friday October 20, 2023 @03:08AM (#63938631) Homepage

    There could be some more advantages to modulate lights, for car cameras.
    Car headlights should also have predefined flicker patterns for easy recognition.

    • No one is considering how massively this would degrade telescope capability. Typically they are trying to capture extremely dim, distant objects photographically. So commonly they use very long exposure times. Constraining them to a super short shutter time cuts the total exposure capacity. Even stacking multiple images, they would be forced to stretch the total session time proportionally. Which multiplies the challenge of tracking accuracy.

      Terrestrial telescopes are still doomed.

      • Re: Exposure = aperture x shutter time (Score:5, Insightful)

        by Baloroth ( 2370816 ) on Friday October 20, 2023 @07:37AM (#63938911)
        This doesn't prevent long exposure times, though it does make them take longer: you can keep the image exposing over multiple shutter cycles. You don't gain any exposure while the shutter is closed, so it'll take longer to gain the same amount of light, but it's still possible.

        • Re: (Score:2)

          by AmiMoJo ( 196126 )

          Seems like it would wear the shutter out quite fast. It would have to be opening and closing 150 times a second, for the entire length of the exposure. That's more than half a million cycles per hour, so even if it was rated for a million cycles it wouldn't last very long.

          • You can easily solve this with a rotary shutter, but as others have pointed out, there are a few other issues here.

          • Re: (Score:3)

            by necro81 ( 917438 )
            Movie film cameras traditionally had mechanical shutters, operating at 30 frames per second, as do film projectors. They aren't maintenance free, but neither is a billion-dollar telescope observatory. It can be tricky to design correctly, but I'd say it's a solvable problem.

      • Re:Exposure = aperture x shutter time (Score:5, Insightful)

        by The Grim Reefer ( 1162755 ) on Friday October 20, 2023 @10:47AM (#63939353)

        No one is considering how massively this would degrade telescope capability.

        Agreed, it does degrade telescope capability. But the real question is, does it degrade the capability less than all the current light pollution? If the choice is much longer exposure times or just not being able to use it then the choice seems obvious.

      • Not all the big of a deal, build the instruments where there are no towns horizon to horizon for the imaging, and we have. The high deserts of the world all have some valley with good observational seeing and just enough of road to drag construction supplies in. With enough adaptive optics the AZ desert outside of flagstaff is about as good as Chile at twice the altitude.

        I observed on midwest campus as an undergrad, observed stars down to Mag 12, many time dimmer than pluto, with a photomultiplier t

    • Thatâ(TM)s a good point. I was wondering why you wouldnâ(TM)t key it off the power frequency (not have the flicker happen at 50/60 Hz, but have everything synchronize when to flicker based on the peak of the power system, since it would be much cheeper than everything having gps chips in). Cars though, or annything mobile, obviously answer that question.

    • Any system that would decrease the retina burning LEDs they have on cars now would be welcome. It is become a struggle to see at night when one of those damn laser cars comes at you.

  • You can try all this all you want, but it wonâ(TM)t happen. Astronomers have been fighting this battle for decades and pretty much gotten nowhere. Itâ(TM)s an unfortunate truth. Astronomers might make progress here and there, but unfortunately thereâ(TM)s just not going to be enough interest. Space telescopes are the only sound tech we have for a completely clear sky. Maybe theyâ(TM)ll get lucky and a government in a country approves it.

    • Thatâ(TM)s because every weapon theyâ(TM)ve had in the war has been to massively inconvenience everyone else. If in the other hand they can get bulb manufacturers on board with adding a cheep, standardised chip to their circuits; or possibly even get government on board requiring it to happen; then it can just magically fix the issue with no intervention from Joe consumer at all.

      • Re: (Score:2)

        by narcc ( 412956 )

        Joe consumer is selectively indifferent...

        "Buy incandescent bulbs! LED lights have government mandated microchips in them to make them flicker as part of their new mind-control program. Don't think that they didn't also sneak in a few spying and tracking features either! Big brother is watching you from every bulb in your house. Wake up sheeple!"

        • Comment removed based on user account deletion

          • All LEDs flicker. This is an inherent to the physical design that allows it to create light. No chip necessary for a natural side effect.

            Low cost PWM drivers cause LEDs to flicker. By spending a few cents more on a constant current driver it becomes possible to power LEDs without flickering.

      • If in the other hand they can get bulb manufacturers on board with adding a cheep, standardised chip to their circuits

        Cheap > Zero. When a large bulk buyer is shopping, the LEDs without the extra parts will be a significant saving. The government administrator making the decision is not responsible for astronomy, nor will they be rewarded for spending extra money to help astronomy.

        Space based telescopes are your future, get used to that. We are already at the point where astronomers don't need to be at the telescopes. It's all digital now, the astronomers can be, and often are, remote.

        Think smaller. Smaller satell

    • As someone who has been foolish enough to get involved in city government I say good luck trying to get a consensus from the voters on having all of the lighting in town modified. You'd have to get private lighting included in it.

  • I mean they would have to be timed to go off at the same time right? Light is probably fast enough that the distance from the light to the telescope might not matter as much, but they would still need to be synchronized it seems like.

    • Re: How do you synchronize all these lights? (Score:5, Informative)

      by king_nebuchadnezzar ( 1134313 ) on Friday October 20, 2023 @03:25AM (#63938651)
      That's what the gps is for. You use it as. Precision timing source. Millisecond accurate timing signals are pretty easy to create. This is actually a pretty practical idea, and the cost per streetlight could easily be under a couple dollars. Not free, but cheap.

      • I think this is a great idea but since the local government cant even sync the time that devices come on correctly to prevent load spikes with devices that are only 1 year old I dont hold out too much hope

        GPS on each light or even PTP implementation is far more sophisticated than these lowest cost device but high energy cost short sighted idiots can manage (and thats when costs directly effect them they still can not manage it).

        regards

        John Jones

             

        • Maybe grid frequency could be the source of the timing here. As long as all the devices in an area are connected to the same distribution grid, you might have a synchronous signal that's way cheaper to read than GPS signal. Just add a frequency multiplier into the mix. Seems like a very simple microcontroller could do that.

          • The signal is too dirty. Clocks that sync to the 60Hz signal drift off after time.

            • Pretty much everywhere the frequency is deliberately adjusted to keep such clocks accurate.

            • But long-term stability is irrelevant for this application. If it drifts for everyone the same, everyone still stays synchronized for the purpose of the telescope shutters.

      • Re: (Score:2)

        by Entrope ( 68843 )

        GPS can get you much better than millisecond accuracy and precision. The usual stability number for the one pulse-per-second output from a GPS receiver is 50 nanoseconds, typically because it's associated with a 10 MHz clock somewhere and simple techniques have an expected synchronization error of half a cycle. Couple that with an OCXO for short-term stability and you can get really impressive clock performance.

        (If budget is of little concern, a rubidium clock is an order of magnitude or two better than a

      • Can you imagine a few hundred or thousand megawatts hammering the grid at the exact same millisecond because all these loads with crappy input filtering are synched? This will become a power problem really quick and may cause massive grid failure. Nobody thinks upstream beyond their one little deviceâ¦

        • Re: (Score:2)

          by Entrope ( 68843 )

          LED lamps generally have transformers with internal capacitive and inductance as part of the AC-to-DC conversion that drives the LEDs. The load gets averaged out as long as the duty cycling is short enough -- and humans would notice duty cycles long enough to cause problems.

          Putting a GPS receiver to steer modulation of light in every street lamp is dumb for other reasons, but not that one.

        • Oh you mean like with normal incandescent bulbs, which in the past "hammered" the grid all at the exact same time because of Ohm's law?

          • He meant what he said, he just knows more than a guy who's heard one EE buzzword in his life.

            All other issues that I'd have to teach you a while to get you to understand aside, this will cause a harmonic at 300Hz ON THE ENTIRE GRID which I promise you would break all sorts of fun things in expensive ways.

            • Don't make promises you can't keep, wise people told me. Your ASSumptions make you...you know what.

            • Wouldn't the inductance values of all the power lines, transformers, and even filter run capacitors basically turn this into less ofva harmonic, and more of a ripple anomaly?

              Remember, even a length of straight wire has a Henry value that is nonzero.

            • As someone who does electronic projects for fun, and designed a system to run a pinball machine with substantially less power than is usually required...

              There's absolutely no reason to think there would be any impact on the power grid by syncing LED flicker at these frequencies. None. It's not even a serious consideration.

              The ham radio side of me knows it'll spew RF at some annoying frequencies though. Cheap Chinese gear will flood the market without shielding, and the frequency used will stomp all over the

        • Re: (Score:3)

          by caseih ( 160668 )

          I can't tell if you're serious or joking.

          No this won't be a problem real quick if it was done. It wouldn't "hammer" the grid the way you suggest. That's not how it works. LEDs are DC devices. So every LED has to have a driver that converts AC to DC, and that driver includes smoothing capacitors. Capacitors not only smooth voltage ripple, but they can also absorb tiny changes in current draw as well. LEDs are already driven with PWM to dim them, yet none of that causes any problems back on the mains, ev

      • Millisecond accuracy isnâ(TM)t accurate enough. Even with military grade GPS the accuracy still isnâ(TM)t enough. Using more than two wavelengths might resolve the problem, but youâ(TM)re looking at a significant expense to upgrade the entire GPS satellite framework.

      • Expanding on this slightly; gpsâ(TM)s signal will get you the time accurate to within 40ns. Getting the required millisecond accuracy is utterly trivial. The trickier thing I suspect is that it puts requirements on the types of lights, and other components you use. LEDs sure can switch on and off that fast, but thereâ(TM)s no room for an incandescent or fluorescent light in such a scheme. LEDs almost certainly will cover the vast majority of lighting going forwards, but there are certainly a bu

  • 150 Hz (Score:5, Interesting)

    by Pinky's Brain ( 1158667 ) on Friday October 20, 2023 @03:24AM (#63938647)

    Yeah, no. 150 Hz on moving objects obviously gives highly visible strobe, what are they smoking?

    Unless it's 150 kHz this is not an option.

  • How about not shining into the sky? (Score:3)

    by thegarbz ( 1787294 ) on Friday October 20, 2023 @03:26AM (#63938653)

    Cities with actual observatories nearby have a very simple solution to this problem. Don't use lights with diffusers that spill a not insignificant portion of light into the sky. And that's before we talk about empty office buildings with their logos lit and their lights on all hours of the day and night.

    • Re: (Score:2)

      by AmiMoJo ( 196126 )

      That helps, but a lot of light still reflects into the sky.

      I'm not sure this scheme will work though. The cost of adding it to every street light is going to be significant too.

      • A simple shade that directs light down instead of letting it bleed to the sides isn't expensive. I worked with a light pollution group at Harvard on this.

  • "Imperceptible" flickers sound like migraine juice (Score:3)

    by Eunomion ( 8640039 ) on Friday October 20, 2023 @03:38AM (#63938665)
    Besides, space telescopes are going to get a lot cheaper as the launch industry advances.

    • There are professional observatories that play a crucial role in detecting e.g. near-Earth orbits that operate on budgets on the order of $10k. Replacing them all with space telescopes is not going to be feasible for decades.

      • Maybe in those areas, they could do the flicker in the very wee hours, when practically nobody is outside.

    • It'll never be cheap. Space telescopes are always pushing the envelope of technology.

  • Some people are very susceptible to headaches caused by flickering, even if it's not consciously perceptible. I expect doing this (if it happens, which it likely won't) would have significant deleterious consequences for some percentage of the population.

  • Great idea, but they are dreaming if they think "The most expensive element of the DarkSkyProtector system is the telescope shutter". The real cost will be in adding a radio receiver to every single light bulb to pick up a synchronising signal that turns them all off at the same time.

  • With Starlink and friends, ground=based astronomy is basically f***ed already.

  • Can this be tuned to the frequency of my personal eyes? I want to see the stars too.

    Failing that, can the streetlights just be turned off? They aren't necessary after let's say 23:00 or even 22:00. If late night city street dwellers want to see better in the middle of the night, they can carry a flashlight with them.

  • You just know that some percentage of the population WILL be sensitive to this strobing effect. I'd hope a lot more testing can be done first
    • I came here to post this. Tech nerds typically know little about the vast differences among people. This will undoubtedly harm some people. If you want a clue, chew on something crunchy while looking at LED Christmas lights or a vacuum fluorescent display. "Who cares? I have a great idea!"

      We've already changed everything to LEDs because it was such a good idea (unforeseen retina damage). [nih.gov]

    • Don't worry, it's not going to happen.

      You can't do this without replacing the power supplies in the lights, which don't have any way to attach such a circuit. It would not only definitely add more than a "couple dollars" of costs even to new units, but existing lights would cost a whole lot more to retrofit.

    • Re: (Score:2)

      by narcc ( 412956 )

      They'll certainly claim that they're sensitive to it, like the people who claim to be sensitive to EMF. You can bet that these special people will magically not be sensitive to strobing on other things at similar frequencies, provided you don't tell them about it ahead of time, of course.

  • There are far more people researching and developing lighting than there are researching and developing telescopes.

  • WTF, people. And no, we don't have that now due to AC and fluorescent lamps: They're on three different phases,
  • is used to dim LED lights. This is no different, only at a lower frequency. The result will be dimmer lights, so the LEDs must shine brighter while they are on to compensate. Which cuts their lifetime short. Or you install more lights. This is by no means a low-cost solution.

  • Use a shaped piece of reflective metal on top instead of this over-engineered "solution" that adds several points of failure and the added bonus of inducing migraines.

  • And they can use block chain to store gps and flicker data.

    Everyone, don't miss out! Buy your BitcoinFlickerLights while they're cheap! They can only go up! Never sell!

    • On the one hand: We can now view the Milky Way with the naked eye
      One the other hand: Terminators

      Meh, what the heck, let's just do it

  • Somewhere in the red region of the spectrum. That has to be cheaper than adding a GPS to every light.

  • Wildlife impact (Score:5, Interesting)

    by stevenm86 ( 780116 ) on Friday October 20, 2023 @08:46AM (#63939067)
    I'm curious what would happen to birds/insects/other wildlife if you immersed them in an environment that's strobing at 150Hz (assuming that's 180Hz for the Americans). Humans might not be able to tell the difference between DC and 150Hz, but what about bees and such?

    • Re: (Score:3)

      by Reemi ( 142518 )

      You are spot on. Chickens can detect flicker up to 140 Hz, so that is very, very close to 150. A lot more research is needed before this can be potentially rolled out.

      • Re: (Score:2)

        by PPH ( 736903 )

        Good points. But we have already been conducting these experiments for several decades at 100 or 120 Hz. Show me the chickens with migranes.

  • Sometimes, humans (or other things) contaminate areas and they just aren't good places to study a particular science. Maybe the real solution isn't to sync worldwide street lights to allow a handful of astronomers to view the sky the way Galileo did ~500 years ago. Perhaps the solution is to launch a few more telescopes into space where manmade light pollution isn't a thing. Then the other 99.99999% of the population doesn't have to jump through hoops to minimize light and radio pollution for those few curi

    • Start putting them on the moon. We'd develop moon base technology and systems while at the same time you could have mirrors too large to put in space supported on the surface of the moon in its weak gravity and ample solar power.

      • Start putting them on the moon. We'd develop moon base technology and systems while at the same time you could have mirrors too large to put in space supported on the surface of the moon in its weak gravity and ample solar power.

        I'm thinking something smaller than moon base alpha. What sized satellite in LEO would give an equivalent image to these light polluted ground based telescopes? Anything bigger than that would seem the most immediate solution. Don't allow mission creep, don't let them try for Webb 2.0. The immediate short term goals is something "better" than their current ground based, more economical and therefore more likely that way.

        Would a small LEO telescope be cheaper than operating the ground based telescope? Wha

  • Suddenly there are widespread migraines being reported all over the country.

    Anyone who has anything to do at night is reporting dull headaches starting about an hour after sunset, growing to piercing, blinding migraines the darker it gets.

  • Don't LED lights flicker anyway?

    I have a (battery powered) headlamp and I notice a flickering pattern when it is raining ( in the motion of the raindrops falling you can see the intermitent streaks)
    This is in the beam of my headlamp, not related to the street lights (there are areas on my way to work that are not well lit.)

    • Re: (Score:2)

      by PPH ( 736903 )

      Yes, if they are operating from some types of switch mode power supply.

    • Yes, you can see it in dash cam videos. It is pretty weird seeing headlights flicker. The idea here is to have the telescope aperture open and close in synch with the LEDs' flicker.

  • Good luck getting entire towns, never mind cities, to retrofit their lighting. Even if you did there are scores of companies and countries racing to fill the skies with satellite streaks anyway.

  • Regular people including kids also have a right to be able to look up in wonder at the night sky. Who's going to fund all those goggles?

    Just use dimmer lights, point them down, and even (God forbid) use less lights. If grown ups are that afraid without a nightlight, perhaps they should invest in a binky.

    As for security, sometimes excess lighting has perverse effects. It provides deep shadows to hide in and provides enough light to commit crimes by. Take away the excess lighting and dark adapted eyes can see

  • Replace lights with ones that output light at a lower frequency. Moving from a 6000k light to 3000k is a 16x reduction in atmospheric scattering. Even switching from 4000k to 3000k is a 3x reduction.

    Been a few years and already LED street lights around town are failing. In whole areas streetlights are turning purple as the phosphors fail in a uniform way while sporadically distributed randomly failing drivers seem to be designed to induce epileptic seizures.

  • How about special viewing devices for the average joe to look at the sky.

    • How about special viewing devices for the average joe to look at the sky.

      That's what the Apple Vision Pro headset is for. To overlay the star you can't see (AR). :-)

      Or for a more modest price get an astronomy app for an iPad and hold it up to the sky at night. The apps use location and time to compute the correct star positions.

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