Is There a Way to Darken Satellites for Astronomers? (scientificamerican.com) 106
Astronomers are searching for solutions to the man-made "constellations" of satellites from SpaceX's Starlink and Amazon's Project Kuiper that they say are interfering with their work. Scientific American reports:
Finally, in August — after more than a year of complaints from the scientific community and damage-control efforts from SpaceX — the National Science Foundation and the American Astronomical Society released a report on the situation. It drew from discussions among more than 250 experts at the virtual Satellite Constellations 1 (SATCON1) workshop earlier this summer to provide recommendations for both astronomers and satellite constellation operators in order to minimize further disruptions...
SpaceX's initial efforts at mitigating the spacecraft's impact involved launching a prototype Starlink satellite known as DarkSat earlier this year that features a black antireflective coating. Recent ground-based observations of DarkSat in orbit found it half as bright as a standard Starlink satellite — a great improvement, according to experts, but still far from what astronomers say is needed... While the dimming techniques tested by DarkSat are far from a sufficient solution, SpaceX has continued to develop other ways to further reduce spacecraft brightness. The company's second attempt at a darkened satellite, VisorSat, uses a black sunshade to reduce light reflection. The first spacecraft with this design was launched on June 3. Astronomers are hoping to observe VisorSat and compare it with DarkSat once observatories reopen, following the COVID-19 shutdown. Even before any detailed observations of VisorSat have been made, SpaceX seems to have doubled down on the new model. All the satellites in the two Starlink batches launched in mid-June and early August were VisorSats, with each carrying its own sunshade.
Astronomers are not yet sure whether darkening methods such as DarkSat and VisorSat are the solution. Of the SATCON1 report's 10 recommendations, only one asks satellite operators to use darkening techniques. The others suggest deploying satellites in orbits below 600 kilometers to minimize their nighttime glare, controlling their orientations in space to reflect less sunlight, developing ways to remove their trails from astronomical observations and making their orbital information available so astronomers can point telescopes away from them. By some mix of approaches from this menu of options, it is hoped, the problem can be managed. Even so, the advent of satellite megaconstellations may have made further degradation of astronomers' view of the night sky inevitable.
It's a problem that's only going to accelerate, argues one astronomer at the University of Washington — adding that it's also a question of precedent. "It's a question of what kind of sky you want your grandkids to have."
SpaceX's initial efforts at mitigating the spacecraft's impact involved launching a prototype Starlink satellite known as DarkSat earlier this year that features a black antireflective coating. Recent ground-based observations of DarkSat in orbit found it half as bright as a standard Starlink satellite — a great improvement, according to experts, but still far from what astronomers say is needed... While the dimming techniques tested by DarkSat are far from a sufficient solution, SpaceX has continued to develop other ways to further reduce spacecraft brightness. The company's second attempt at a darkened satellite, VisorSat, uses a black sunshade to reduce light reflection. The first spacecraft with this design was launched on June 3. Astronomers are hoping to observe VisorSat and compare it with DarkSat once observatories reopen, following the COVID-19 shutdown. Even before any detailed observations of VisorSat have been made, SpaceX seems to have doubled down on the new model. All the satellites in the two Starlink batches launched in mid-June and early August were VisorSats, with each carrying its own sunshade.
Astronomers are not yet sure whether darkening methods such as DarkSat and VisorSat are the solution. Of the SATCON1 report's 10 recommendations, only one asks satellite operators to use darkening techniques. The others suggest deploying satellites in orbits below 600 kilometers to minimize their nighttime glare, controlling their orientations in space to reflect less sunlight, developing ways to remove their trails from astronomical observations and making their orbital information available so astronomers can point telescopes away from them. By some mix of approaches from this menu of options, it is hoped, the problem can be managed. Even so, the advent of satellite megaconstellations may have made further degradation of astronomers' view of the night sky inevitable.
It's a problem that's only going to accelerate, argues one astronomer at the University of Washington — adding that it's also a question of precedent. "It's a question of what kind of sky you want your grandkids to have."
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What percentage of all planned observation time (at all active observatories) is completely ruined?
1. All of it, potentially. Interferance is entirely random from the astronomers perspective and things are getting a lot worse. Telescope time is precious and there is a long lead time involved in acquiring access, adding the task of finding windows between these increasingly common satellite traversals makes it impossible to bag a clean slot.
What percentage is damaged but could be partially mitigated?
2. What do you consider to be partial mitigation? Guarantee an order of magnitude or less error in measurements, in probability, in wavelength, in angle? there is fine
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Indeed. Sometimes the simplest solutions are the most cost-effective.
If bright satellites reduce the effectiveness of telescopes by, say, 10%, then instead of making the satellites darker, it may be more cost-effective to install 10% more telescopes.
I was once involved in a project to make solar panels more efficient by clearing dust off them. The dust could reduce electricity generation by 10-20%. Every technique we considered was far less cost-effective than just installing 20% more panels.
KISS.
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The problem is the telescopes are all owned by different orgs so it's not as easy as just "build more". There would need to be a global satellite tax or something to fund those orgs.
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Digitally remove them? (Score:3)
A satellite trail is pretty obvious. I think long exposures are actually made with several shorter exposures to be able to remove other noise, much like phone cameras these days.
So just remove the trails from the sub-images that have them.
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This is the one way that astronomy actually wins as more satellites go up: make the companies that launch and own satellites pay for additional telescopes before the launch is allowed or the sate
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How about stealthy satellites, no water up there to expose their motions. No one would see anything, only problem all those stealthy satellites would not be able to see each and go with bet guess safe navigation and quite a few stealthy satellite impacts on stealthy satellites. You just know there would be some up there already, stealthy planes, so stealthy satellites.
It Doesn't Work Like That... (Score:2)
1. Ground-based telescopes
2. A constellation of bright satellites in Low Earth Orbit (LEO)
3. Distant astronomical objects the telescopes want to image
Adding more telescopes on what is essentially the 'wrong side of the problem' will simply mean that more telescope operators will report the issue.
Realistically, there are only two options: one, resolve the problem of satellite interference by making them com
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Why only 10% more?
Just mandate that all such view obstructing satellites must have an observatory platform module installed on them, pointing away from earth.
Transform those trash satellites into the planet's largest interferometric telescope array.
PROBLEM SOLVED.
Re:Still insufficient data (Score:5, Informative)
I've not been able to get well researched answers to some simple questions [...]I haven't even seen anyone make a serious effort in answering these questions. Without quantifiable data how am I supposed to know if I should care, how am I supposed to know if this is a significant issue?
The National Science Foundation and the American Astronomical Society hosted a workshop on the effects of satellite constellations on astronomy in July and the presentations are available here:
https://aas.org/satellite-cons... [aas.org]
This workshop gathered together astronomers, satellite operators, dark-sky advocates, policy-makers, and other stakeholders and interested parties to discuss, understand, and quantify the impacts of large satellite constellations on astronomy and the human experience of the night sky. The goal was to work collectively towards effective solutions to mitigate those impacts and to publish them in a report which will be widely distributed.
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> What percentage of all planned observation time (at all active observatories) is completely ruined?
I'd expect local populations with urban light pollution to be a much larger problem. Earh's problem and urban sprawl continue to encroach on the most isolated parts of our available land.
I'd expect the long-term solution to be moving optical and radio telescopes to orbit themselves.
Regarding the last line . . . (Score:4, Interesting)
It's a question of what kind of sky you want your grandkids to have.
I'm perfectly fine with my grandkids having a nighttime sky with a bunch of visible satellites in it, just like I'm fine with there being airplane lights in it.
The people whose science is being interfered with have a point. The people arguing aesthetics can be dismissed.
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In this case, sir, not as a general principle.
The entire aesthetic issue over the satellites is not about whether there should be pinpoints of light in the night sky, but exactly where they should be and how fast they move. That's so blatantly far over into de gustibus non est disputandum that anyone who would actually try to make a "think of the children" argument (or, like the gentleman below, analogize it to a garbage dump) are obviously not playing with a full deck.
Arguing with them is therefore both po
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Why should aesthetic concerns be dismissed?
Because it's subjective. Someone else might think airplane lights, windmills, and skyscrapers are pretty. Even if they are all man-made. How do you even form a logical argument for or against some aesthetic?
Re:Regarding the last line . . . (Score:5, Insightful)
Also, your grandkids' sky will have Phobos in it
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This is unlikely in the extreme. Colonization of another planet is vstly more difficult than landing a few people for a few days isit.
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Aesthetics have a value on their own, it is just hard to monetize it and so hold out against more easily monetized uses of a shared resource. Kind of the same argument about preserving those old growth forests when the trees can be turned into redwood decks and the land opened up for agriculture. Or saving the last rhinoceros when the horn can be sold and the land grazed with cattle. As they used to say often, "That's progress". I'm not saying that everything has to be "preserved", but the economic trad
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Aesthetics in general are fine.
In this case, however, it's an argument over the precise arrangement of points of light on a dark background. Someone who goes "Think of the children!" over that is obviously overwrought.
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I'm perfectly fine with my grandkids having a nighttime sky with a bunch of visible satellites in it, just like I'm fine with there being airplane lights in it.
Which is precisely why your night sky looks like light polluted rubbish. Are you also happy if we build a garbage dump next to your house providing we can control the smell? Or are you maybe being selective as to what aesthetics you care about without any consideration that other people like different things.
Thank god we have modern technology to build huge telescopes LPR filters, or even to launch our telescopes in space because Charles Messier would have been able to catalog fuck all with the damage we've
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Why control the smell? Smell is part of aesthetics as well.
Who's sky is it, anyway? (Score:1)
American firms who want to shoot satellites into orbit need the go ahead from the FCC, although their satellites will be mucking up the whole world's skies.
While having separate jurisdictions would be a nightmare, perhaps some common point of action should be identified?
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FCC is actually an agency whose role is to oversee the US obligations to international spectrum acclocation treaties. I don't think they're the right agency to be a sole arbiter for satellites, but a portion of satellite impact will be electromagnetic radiation that could interfere with communications, so it makes sense to need FCC (or.. ITU, if there is an enforcement arm, maybe?) approval for satellites designed to be launched and operate over the United States.
I think the issue is whether we have an agen
Wrong question? (Score:2)
Is there a way to get astronomical observations from orbit, past all those other satellites?
What about setting up astronomical observations posts on the moon or on Mars?
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Except that a telescope on the moon would spend a couple weeks pointed at the sun every month. And lunar regolith is like dust sized razorblades.
Satellites are far superior as they don't have to deal with any of that.
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the temperature extremes and relatively frequent meteor bombardment make problems that a purely orbital satellite would not have.
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No (Score:2)
The key element in an optical telescope is the primary mirror. It's a big round mirror, perfectly shaped and perfectly polished, mounted inside the telescope tube.
When I say perfect, if such a mirror were the size of the gulf of Texas, the "hills", or non-flatness, would be mere inches. So it's a very precise instrument.
Large telescopes have 10 meter mirrors. The size of mirror largely determines how well the telescope can work, because of certain physics. So the question is if we can pack a tube contai
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Except building a large telescope mirror ON EARTH takes the best labs a few years. So first you have to build facilities that rival the best on Earth, and get the best technicians on Earth to go live in the moon for a few months ...
An array of small mirrors isn't the same, though it could be deployed to the moon. Of course, it needs to be on the side of the moon which faces earth in order to get data back.
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Build it in space. Some tipes of machining are, theoretically, much easier in zero gravity.
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I have no doubt that there is something that is easier in space, I don't know that making beryllium glass is one of those.
I'm fairly sure that grinding said glass parabolic to 10nm precision (the same precision as Intel's chips) isn't one, and even getting the necessary equipment up there is likely to be a challenge.
You may recall that for Hubble, Kodak had made a back up mirror. Yet the $5 billion instrument was nearly scrapped because *installing* the mirror in space was considered impossible, despite the
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> What the fuck is "the gulf of Texas"?
Bad editing, that's what it is. Texas. Just Texas.
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Space based instruments are FAR more expensive than similar sized terrestrial ones.Some observations need to be done in space, but otherwise a lot more science can be done for the budget on earth.
I think the cost ratio is > 100:1,
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Its all about funding. I'd love to work on space telescopes - I actually have a little funding to do so, but overall its just fantastically expensive.
Its not just launch costs - building a device that can be operated remotely adds a lot to the cost.
For a billion $ we can build a square kilometer of radio telescopes that can map the density of hydrogen in a large fraction of the universe, and provide a lot of information on dark energy and dark matter in the early universe.
For the same billion $ we can laun
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Space based instruments are FAR more expensive than similar sized terrestrial ones.Some observations need to be done in space, but otherwise a lot more science can be done for the budget on earth.
Obviously not, or we wouldn't have the problem of too many satellites blocking the view of telescopes.
Just write a grant to put some cameras on the top side of the Starlink satellites and send the data back down their link, tweet Elon Musk, and bob's your uncle. He wins on the PR front, astronomy wins with a giant distributed telescope with an effective aperture on the order of the size of the earth, and we can all live happily ever after.
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So we are on the same page,
The LSST (now called Rubin Observatory) https://en.wikipedia.org/wiki/... [wikipedia.org] has a 8.4M main mirror
https://en.wikipedia.org/wiki/... [wikipedia.org]
It cost around $500M to build
The James webb space telescope has a 6.5M main mirror
https://en.wikipedia.org/wiki/... [wikipedia.org]
and cost 10 billion to build and has about 1/2 the collection area of the Rubin observatory.
For radio telescopes its worse: The proposed PUMA array is 30,000 X 6 meter dishes covering a square kilometer, Budget in the 500M-1B range
the st
One word (Score:2)
Vantablack. Coat these suckers in it and you'll never have to worry about them interfering with astronomy ever again.
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Two words: solar panels. These do most of the reflecting, and don't work covered with Vantablack...
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Two words: solar panels. These do most of the reflecting, and don't work covered with Vantablack...
I did say coat them.
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If the collecting side of the panel is facing the earth you're doing it wrong.
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You should be pointing your solar panels almost directly at the Earth around midnight. Because that's where the Sun is and it costs a lot of fuel to keep changing your orientation for no good reason every day.
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There's no sun to be had at midnight no matter where you point for a leo satellite, and it wastes energy reorienting them towards the earth when there is never any sun there. If you didn't spend any fuel on orientation of the panels, they would be fixed facing directly away from the planet at all times. If you are tracking the sun, they would have varying angles of away, with the closest to facing being roughly 90 degrees parallel for dawn/dusk.
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Fuck Anish Kapoor- use Black 3.0 instead.
better solution (Score:2)
besides painting the satellites black. (which is what the current solution is). Why not put a camera on each satellite? Then astronomers can get their view unobstructed, and also have many views with which to construct a composite high definition image.
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Yeah- I think that part of SpaceX's 'tax' or 'launch requirements' should be to provide a network of low-mid power space telescopes that are available for public use. I'd bet they could engineer something with a ~30" mirror and launch 60 at a time. It may be less romantic than a back yard telescope, but they'd be better than +99% of ground scopes.
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Because any possible camera that could be mounted on such a satellite is (roughly) completely scientifically useless when compared to an astronomical telescope.
Wait until the sky is full of space stations (Score:2)
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Only reflects for a short period (Score:4, Informative)
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Not much help for radio telescopes though.
Use the Moon (Score:1)
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The fact that there is absolutely zero infrastructure on the moon for any kind of construction aside from precision optics is kind of a deal breaker.
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The conversation is about making it on the moon.
Ahaa, I see, silly me I just assumed that of course you will have to land it if you plan to have a scope on the Moon, didn't know you had the capacity to make a useful telescope on the Moon. Best of luck with that plan.
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HERF guns. (Score:1)
How much radiated power would be necessary? Satellites could 'go dark' fairly easily. Astronomers woul be pretty good at finding locations and aiming.
Fuck off with this (Score:4, Interesting)
This is only an issue for wide field astonomy .. which is better suited for space observatories anyway. For narrow field observation, the probability of being in the path of a SpaceX satellite is nearly zero (you won't be doing deep space observation until well past twilight) .. ALSO, the orbits are published online and updated in realtime .. you will know days in advance when and if a Starlink satellite will cross your path and you can turn off your camera for those milliseconds. Or just look at something else that day.
Besides, 99% of people "concerned" about this hated astronomy anyway. They just are technology haters, most of them anyway. You can claim to be a fan of astronomy but try to squish the space industry? If we let the space industry flourish and develop, can have big ass space telescopes eventually .. which is what's really needed for astronomy. The Earth has an atmosphere which blocks a lot of stuff and has weird phenomena in it (clouds, lightening, airplanes etc.).
Re:Fuck off with this (Score:5, Interesting)
This is only an issue for wide field astonomy
Which is an actual field of science we do. But don't take it from me, take it to the scientists who are concerned.
For narrow field observation, the probability of being in the path of a SpaceX satellite is nearly zero
I see you've never actually done any astronomy. Please leave subjects you know nothing about to the experts.
Re:Fuck off with this (Score:5, Interesting)
I like space AND I do wide field astronomy. (which is one of the primary tools for cosmology)
I'm not religious on this. I would like to find a way t do communication and keep astronomy going. I love to put telescopes in space, but right now its >100X more expensive, and I don't see any likelyhood of the astronomy budget being increased by that much. (for example the CMB-S4 radio telescope system is >$500M, I just don't see anyone coughing up >$50B to put it in space.
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I would like to find a way t do communication and keep astronomy going. I love to put telescopes in space, but right now its >100X more expensive, and I don't see any likelyhood of the astronomy budget being increased by that much.
The key is, "right now". I'm hoping the space based telecommunications revolution will change the economics to make this no longer true. As access to space becomes cheaper, space based telescope arrays may become less expensive due to no longer needing vast tracts of land to build them on.
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You seem to be unaware that Starlink birds will visible until deep into the night.
what do you mean? brightness? (Score:1)
US Federal Glossary of Telecommunication Terms (FS-1037C), "brightness" should be used only for non-quantitative references to physiological sensations and perceptions of light.
If this is astronomy use magnitude. If its the satellite's surface use albedo. If the sat is darker, it will heat up on the sun-ward side and cool on the opposite side. This could cause big problems.
Stacking? (Score:4)
I know a couple of amateur astronomers; they all use multiple exposures (a few seconds or a minute each) and then use software to detect and eliminate satellite streaks as well as artifacts from cosmic rays that are absorbed by the camera sensor. The result is that some pixels in the final image will be the average of 99 frames rather than 100. Does anyone know what makes this a problem for scientific observations?
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I know a couple of amateur astronomers; they all use multiple exposures (a few seconds or a minute each) and then use software to detect and eliminate satellite streaks as well as artifacts from cosmic rays that are absorbed by the camera sensor. The result is that some pixels in the final image will be the average of 99 frames rather than 100. Does anyone know what makes this a problem for scientific observations?
I've been out of the astronomy field for a few years, but I can give you a few ideas. A lot is going to have to do with what science you're doing - for example, narrow vs wide-field and faint vs bright targets are two main differences that will affect things.
A major problem is CCD issues. The biggest would probably be read out time. Most astronomical CCDs are designed for long exposures and no one has optimized the time it takes to read the actual data. Most CCDs (even at the world's best observatories) tak
You can darken it sure (Score:2)
paradigm shift on the horizon (Score:2)
This problem will go away on its own in the not-too-distant future. Earth-based observations have always had a number of serious limitations, but astronomers are used to living with them and the available instruments were not good enough so that those base limitations (light pollution, atmospheric turbulence, the Earth's rotation, the limitations of observation time due to day/night cycle, etc) were the big issue. In recent years ground based telescopes have made amazing strides but they are still limited b
Black satellites will have thermal issues (Score:2)
Satellites are usually wrapped in multiple layers of aluminium- or gold-coated mylar sheets, for thermal insulation. A lot of electronics likes to be at room temperature, but in space, you have 3 K in the dark parts of the sky and 1400 W/m2 of solar irradiation on the sun-facing side. Most of the sunlight is reflected from the metal coating, but if you paint it black, the surface temperature will be 120 C (to lose the heat as thermal radiation). That will require more thermal insulation (but the dissipated
Rockets (Score:1)
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No, Elon's solution is probably to tell the astronomers to move to Mars.
Last time ... (Score:2)
The last time this issue was on Slashdot, I posted about it, saying it is a real problem [slashdot.org].
The replies were dismissive, saying this is not a problem, and even someone said I was projecting my hobby on science! Talk about armchair experts ...
And in an unrelated incident (Score:2)
The scientist who didn't get the memo invented a cloaking device for satellites.
Oh bullshit (Score:2)
This is a software problem only. (Score:2)
It turns out if you take a photograph, take another photograph, take another photograph, and keep going, and discard the brightest pixels from the N photographs and sum the others dividing the sum by the number of used photos, then you erase moving objects such as airplanes and satellites, shooting stars, from your integration for super long exposures. Take thousands of these photographs - a few each second and integrate them to get the long exposures.
It's a software problem. All it requires is enough memor
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R.I.P. rotating asteroid and TNO detection.
Embed Telescopes In The Sattelites! (Score:1)
hmmm... (Score:2)
Is There a Way to Darken Satellites for Astronomer (Score:1)
I know how... (Score:2)
Pew Pew Pew Pew
Start with StarLink ...
Dark matter (Score:2)
YES.... (Score:2)
You paint them with a coating similar to stealth craft. Light and radar absorbent matte black coating.
Been saying this for years...
Use better algorithms, and use cheap launches (Score:2)
On the other hand, the cause of this problem is cheap access to space. Starlink is pushing 60 satellites in a single launch that costs a couple of million dollars.
Why not launch cheap (for some value of cheap) telescopes into space? Not everything has to be the Hubble or the We
Same problems down the line (Score:1)
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