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from the has-this-been-thought-through? dept.
Arthur T Knackerbracket has found the following story:
Skywatchers in Spain recording meteors being transformed into brilliant streaks of light by atmospheric compression are a bit miffed – as their view was rudely interrupted by a slew of Elon Musk’s Starlink satellites.
Below is a short clip of what it looked like above La Palma, one of Spain’s Canary Islands last week. The meteor shower known as Alpha Monocerotids crisscrossed the sky, though it becomes hard to spot them once the satellites come flooding in.
SpaceX's table-sized Starlink birds, which sport reflective solar panels, are closer and brighter as they zip across the camera’s line of sight like machine gun bullets.
Starlink satellites during a meteor shower on Nov. 22. pic.twitter.com/wJVk1qu49E
— Patrick Treuthardt, Ph.D. (@PTreuthardt)
Denis Vida, a geophysics PhD student at the University of Western Ontario, Canada, who wrote the code to generate the footage above captured from one of the Global Meteor Network’s cameras, said the obstruction happens every day.
“Note that this was not a one time occurrence,” he told The Register. “We see this every day before dawn with about half the cameras in our network. During that time we effectively lose about half our field of view because of this.
[...] “These satellites will most definitely interfere with important astronomical observations which can have implications on predicting future meteor shower outburst. Accurate meteor shower predictions are essential for understanding the hazard they pose to spacecraft – do you see the irony? – and astronauts in orbit.
(Score: 3, Interesting) by Anonymous Coward on Saturday November 30 2019, @12:53PM (2 children)
I'm a big fan of astronomy and also quite peeved at how little I can see inside the city now a days due to little more than light pollution.
I imagine as bright permanent lights started to become a normal thing there were also similar complaints.
Just kind of interesting to consider we're probably at another inflection point. Starlink isn't the end. It's just the beginning. In the future there will probably be tens of thousands of very low orbit satellites zipping about, everywhere. It'll make the sky quite a spectacle at night, but yeah - ground based casual astronomy will probably become a thing of the past where people reminisce back on the times we've had had, times where, nonetheless, 99.9999% of people failed to ever really take advantage of such natural beauty.
(Score: 5, Informative) by Pslytely Psycho on Saturday November 30 2019, @01:10PM (1 child)
Starlink itself is supposed to consist of 42,000 satellites. So of course at some point.
For a comparison:
So Musk intends to launch nearly 10 times more satellites than the total amount currently in orbit.
https://www.geospatialworld.net/blogs/do-you-know-how-many-satellites-earth/ [geospatialworld.net]
Alex Jones lawyer inspires new TV series: CSI Moron Division.
(Score: 2) by Pslytely Psycho on Saturday November 30 2019, @01:14PM
AAARRGG!
Hit Submit instead of Preview.
"So of course at some point."
Was supposed to be corrected to "So of course competition will likely increase the total to truly incredible numbers at some point ."
Finger flub....
Alex Jones lawyer inspires new TV series: CSI Moron Division.
(Score: 4, Insightful) by esperto123 on Saturday November 30 2019, @01:25PM (12 children)
I'm not an astronomer, but the video is pretty damn cool, but it will not be constantly like that, that happened because the satellites from the last launch are not in their final orbit yet and are pretty close to each other still.
One thing that I said on the first articles several months ago of astronomer complaining about the potential of the starlink satellites to affect their job, is that they are not considering how these satellites are a proving ground to huge swarms of cheap constellations that can be used by them, just imagine a swarm hundreds of satellites performing interferometry as a telescope the size of the earth!
To me this is like people complaining about automation during the industrial revolution.
(Score: 3, Informative) by esperto123 on Saturday November 30 2019, @01:28PM
and to complement, there are several other satellites in that footage, not only starlink, and the brightness is also high on starlink because the orbit is still pretty low, once it reaches 550km it will drop by a lot.
(Score: 0) by Anonymous Coward on Saturday November 30 2019, @03:14PM (1 child)
You do not have an appreciation for the technical challenges that are involved to do that and it ain't going to happen.
(Score: 1) by khallow on Saturday November 30 2019, @03:49PM
You can get resolving power pretty high when you're no longer near Earth.
(Score: 5, Informative) by fyngyrz on Saturday November 30 2019, @03:22PM (7 children)
Imagining it is to immediately realize it's a very poor approach.
Such a grouping of observation units would be far better off positioned well away from the earth, where the earth itself was a lot less in the way than it would be WRT satellites in orbit trying to point anywhere — with an orbiting constellation, the earth would always be in the way of about half the constellation.
When we finally get around to creating interferometry-based telescope systems in space, I certainly hope we do it in (relatively) deep space.
Another thing: if the individual interferometry units aren't stuck in earth orbit, the baselines can be much, much larger between units, and baselines that are as large as possible are critical to the methodology.
--
Use promo code "NETFLIX" to get 50% off your social life!
(Score: 2) by jasassin on Saturday November 30 2019, @08:16PM (2 children)
Methinks you've never heard of Netflix and chill.
jasassin@gmail.com GPG Key ID: 0xE6462C68A9A3DB5A
(Score: 3, Touché) by MostCynical on Saturday November 30 2019, @11:00PM
do you actually need a real netflix account for that?
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 3, Insightful) by fyngyrz on Monday December 02 2019, @01:52PM
Oh no, well aware. I don't do a lot of "chilling" though. I prefer to directly interact with my friends and family as much as possible. Vegetating in front of the various drool boxes isn't my idea of being social in any positive way.
But then, I grew up before watching TV was how one entertained one's self or spent time with friends. So I know how. I'm afraid that is very much a lost skill in recent generations. I truly pity those people — and there are a lot of them — who spend large amounts of time with their faces hovering over their smartphones, planted in front of the television for hours a day, trying to find social contact online, etc.
These folks literally do not know what they are missing.
Oh well. Not my problem. 😊
--
Stupidity is actually a superpower. We learn this when
we repeatedly fail to defeat it with intelligence.
(Score: 0) by Anonymous Coward on Monday December 02 2019, @01:19PM (3 children)
What makes this impractical, assuming of course you've worked out the technical details of how to sufficiently get the absolute positional knowledge of your telescopes as well as hold their relative positioning to handfuls of nanometers, is that your signal is limited by the area of your virtual telescope aperture. Sure, putting them spaced very large distances apart gets you the angular resolution of an aperture with a diameter of that separation (but only in the direction between the two!), but your signal-to-noise is horrible because the combined collection area of the telescopes is only a very, very small fraction of the virtual aperture. Your signal for the virtual telescope goes as the ratio of the actual aperture area to the virtual aperture area.
For instance, take two Hubble telescopes (2.4 meter diameter, or let's just consider the diameter--call it D_h). If you wrap some space-grade duct tape around them and fly the two tubes, the circle that circumscribes them has a diameter of 2 Hubbles (D = 2*D_h) giving a collection efficiency (e = (D_h/D)^2) of 25%. Now separate them so that they are 10 Hubble diameters apart (measured from their edges, to make the math easier), now the collection efficiency is 1%. You can see where this is going REAL fast. So to improve your signal-to-noise, you fly more telescopes (or you integrate that much longer), but in general you'll never fly enough to overcome the signal collection problem except for some very specific limiting cases. You've got a much better chance doing it at RF wavelengths (basically, moving the VLBA into space) because you don't need to actively maintain the relative phases of the apertures (you can time-tag the data as it is collected and phase it up in post processing), but you still need their relative position knowledge to a fraction of the wavelength.
(Score: 2) by fyngyrz on Monday December 02 2019, @01:41PM (2 children)
In a deep-space array, you can put the units anywhere you want relative to each other. At any time, really. So as you increase the size of the array over time, you can vary the aperture as appropriate for the task at hand.
You could arrange the units at the same spacing they would have had in orbit (or better it), but without the observational penalties of being in orbit: a deep space array has considerably less in the way of its observations than an orbiting array, so it can inherently observe more things, more easily, with more active units of the constellation at any one time.
The significant problem with a deep space array is mainly getting them out there — the initial cost is higher. But the performance advantages are clear. There's an additional advantage as well... in orbit, there's a practical limit to the number of units one can deploy, and higher risk to them as well; there are already way too many bits of broken/obsolete junk and currently active tech zipping around up there. And these things interfere with ground-based observation and pollute the view of the sky, too. But moving away from earth orbit, the available deployment opportunities skyrocket, no pun intended, but well, there it is. 😊
Ideally, such an observational system would be established sooner rather than later, even if small, and then added to constantly as there is always a benefit to be had by doing so although that decreases in magnitude as the array gets larger. Still, more units and a larger baseline will always be better to some degree. Such an array would ideally be added to automatically and cost-free once robotic space-based manufacturing finally gets happening, which is something we really need to do anyway.
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No, I didn't trip. That was a random gravity check.
(Score: 0) by Anonymous Coward on Monday December 02 2019, @08:21PM (1 child)
If we're talking about optical wavelengths here, I think you don't have an appreciation for the technical challenges that are involved. Getting them into a deep space orbit is by far the easiest part of the whole thing. Even just doing two telescopes on separated spacecraft is one of those "maybe next decade" problem. The thing that gets you is that this kind of coherent beam combination needs to be done in real time before you take the data, not after-the-fact like you can do with RF wavelengths. So you need to phase up the light from a distance source, which means measuring and maintaining the optical path length between all of the separate telescopes to the tens of nanometers level. Not only do you need to hold the relative pathlengths stable, you need to make them equal. It is easy to picture this with a 2-telescope system where their beams are combined in the middle. If the beam combiner is exactly halfway between the two telescopes and they are looking at a distant source directly in front of them, that is easy to visualize to see how that would be done.
Now lets say the source is 45 degrees off to the side in the direction of one of the telescopes. If your telescope separation is L, then without moving anything you've now added 0.707*L of optical pathlength between the light hitting each telescope because that is the extra distance the light has to travel to enter the further away telescope. So you now need to make up this pathlength somehow. Two things you can do is to rotate the whole array so that the new source is directly in front of them again, or you have to add optical path length to the telescope that gets hit with the light first. Let's say your telescopes are spaced 1-km apart, so somehow you need to add 707 meters of delay. The way they do it with the Navy Precision Optical Interferometer [lowell.edu] is that they have a set of little cars on tracks with mirrors on them where each one can move something like 30 meters, so as a star passes overhead, the delay lines move in and out to maintain the same optical pathlength between each telescope.
What is implied in the above is that you can in principle measure the separation between the two telescopes to tens of nanometers, and even hold that relative position, but you can't measure the out-of-plane differences between the two. Think of the case where your two telescopes are not in a plane, but one is a little bit closer to the star than the other, but you have to measure that distance from within in the plane. You quickly end up with your "small" separate telescopes not being large spacecraft to handle all the pathlength interferometers you need to make those measurements, plus the pathlength corrective piezoelectric elements, plus all the station keeping and (very high) precision gyros, etc., etc., etc.
I'll leave as a problem for the student to consider pointing stability and accuracy (hint: turn it all into pathlength differences).
It is a really really really hard thing to do, and we're just talking about two individual telescopes (plus a third to be the beam combiner).
I should note that the LIGO-in-space ideas are a lot easier to do because you are not trying to phase up on a distance source, but upon each other. But keep in mind that even though that is "a lot easier", that is still a really hard engineering problem that will take many years of development to pull off (and those LIGO-like spacecraft won't be little cubesats).
(Score: 2) by fyngyrz on Wednesday December 04 2019, @12:50AM
No doubt; I never thought otherwise. But in the end, that part of it is just an engineering problem.
Engineers will be happy to solve those things.
The real problems are are money and politics. But I repeat myself.
--
Some drink from the fountain of knowledge. Others gargle.
(Score: 2) by Immerman on Saturday November 30 2019, @04:21PM
I'm not sure how exactly they lose half their field of view either. I could still clearly see plenty of meteors during the satellite transit, though perhaps some of the fainter ones were drowned out. Now, that is no doubt an extra hassle to exclude the satellites from analysis, but it should be feasible so long as there's a publicly accessible database containing up-to-the-minute orbital characterizations of all the satellites (and a historical log for when analyzing older footage)
(Score: 1, Funny) by Anonymous Coward on Saturday November 30 2019, @03:04PM
Any astronomer who gets his shot bombed by starlink gets a discount coupon to offset the cost of launching a space telescope.
(Score: 0) by Anonymous Coward on Saturday November 30 2019, @04:29PM
You can check for visible passes from your location here...
https://www.heavens-above.com/PassSummary.aspx?satid=70003 [heavens-above.com]
(Score: 2) by takyon on Saturday November 30 2019, @06:19PM (3 children)
Is this due to the specific orbit of this group of satellites causing them to cross overhead repeatedly, or that they are at a lower altitude than they will be later?
If you're complaining about this now, the next 41,878 satellites are really going to hurt. And the existing ~2k non-Starlink sats plus airplanes must already hurt. Maybe the problem isn't actually Starlink.
My guess is that the problems for ground-based astronomy will be solved by looking at more distant targets (as something like the VLT would tend to do), or using some kind of computational method to better filter out satellites without compromising quality much. Shorten exposure times and then combine the images. Use Starlink tracking data to help.
One thing to note [phys.org]:
Bolded part is true. Space telescope are better in almost every way. While space telescopes are smaller than most ground-based telescopes today, they don't face the same structural limits and could be made to have larger apertures than any ground-based telescope, or use a swarm-based configuration, also with less limits than similar concepts on the ground.
But the important part is that there is a conflict of interest here. Musk is going to (seemingly) ruin astronomy and then offer the solution: cheap Starship launches of massive space telescopes. Once astronomers figure that part out, they are going to be even more peeved.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by dry on Sunday December 01 2019, @01:43AM (2 children)
Need a lot of space telescopes to equal the millions of amateur astronomers.
(Score: 2) by takyon on Sunday December 01 2019, @05:04AM (1 child)
Look at what LSST [wikipedia.org] is designed for. That's a telescope that won't become 100% useless due to Starlink, but there are already complaints about it. It has a wide field of view and can image the entire night sky every few days.
To match the capability of amateur astronomers, you would probably want to watch the entire sky continuously, in order to capture all transient events. LSST covers 9.6 square degrees, and the sky is 41,253 square degrees. So you would need about 4,300 LSSTs. Round up to 10,000 to provide overlapping coverage.
If you are able to compact LSST's FOV into a CubeSat form factor (with much less light collecting capability and etendue), you could theoretically launch that many in a single Starship flight. It will probably take more flights and larger telescopes but hundreds or thousands of Starship flights doesn't cost much. It comes down to how cheaply you can make telescopes. Of course, launching another 10,000 objects will baffle ground-based astronomy more. Each telescope could send back long exposures as well as a continuous live video feed.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by dry on Sunday December 01 2019, @06:03AM
It's one way around the problem.
(Score: 0) by Anonymous Coward on Saturday November 30 2019, @08:10PM
if you don't have teletubby bunker money elon will kill you with 5g and you won't have to worry about whether you can see the stars or not.
(Score: 2) by jasassin on Saturday November 30 2019, @08:22PM (3 children)
I can't wait until some rouge mastermind with a will and a way designs a satellite that hunts and destroys other satellites. Props if the satellites being hunted can be modified to become hunters themselves. They could clean out the orbit and then suicide dive into Musk's Starlink factories.
jasassin@gmail.com GPG Key ID: 0xE6462C68A9A3DB5A
(Score: 3, Informative) by takyon on Saturday November 30 2019, @09:15PM (1 child)
The U.S. probably already has anti-satellite offensive capabilities attached to some of its own satellites.
https://en.wikipedia.org/wiki/Space_weapon#Space-to-space_weapons [wikipedia.org]
https://en.wikipedia.org/wiki/Anti-satellite_weapon [wikipedia.org]
It's cheaper to use ground-based weapons to destroy a satellite, but it's less covert.
If you consider the X-37B to be a satellite, it can probably be used to envelop and mutilate an enemy satellite.
Probably the biggest problem with a satellite hunter would be changing the orbit to catch up with more than a small number of satellites. This would be solved if emdrive was real.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by jasassin on Sunday December 01 2019, @01:56AM
https://en.wikipedia.org/wiki/Anti-satellite_weapon [wikipedia.org] [wikipedia.org]
From the wiki:
"In general use of explosive and kinetic kill systems is limited to relatively low altitude due to space debris issues and so as to avoid leaving debris from launch in orbit."
Sounds like it would be much easier for an evil mastermind to just scatter a few billion aluminum ball bearings around the orbit, totally fucking it over forever.
jasassin@gmail.com GPG Key ID: 0xE6462C68A9A3DB5A
(Score: 3, Informative) by anotherblackhat on Sunday December 01 2019, @05:06PM
It's called a keg of nails.
Put a few tonnes of nails in orbit spinning the opposite direction that most satellites spin. (or marbles, or rocks)
There's a good chance one of them will collide with something, at orbital speeds.
Put a slight spin on the mass of nails/marbles/rocks and they slowly spread out.
If you miss on the first pass, you get another chance every 45 minutes.
And each time you hit something, you get more shrapnel.
In other words, it modifies the first satellite it hits into more satellite killers, just like you wanted.
(see https://en.wikipedia.org/wiki/Kessler_syndrome [wikipedia.org] ).
(Score: 0) by Anonymous Coward on Sunday December 01 2019, @01:20PM
Astrophotography cameras have a background noise level which makes short exposures of dim objects problematic.
Per pixel read out noise can't be greater than the light the pixel has had time to gather from the dim object
This puts one between a rock and a hard spot because you need to gather in short exposures to be able to reject glints for the sats.
I can see how these satellites could spoil the picture there.
but..
The meteor you are trying to detect is bright and moving.
So you want lots of short exposures.
Why does his not capture enough unspoiled information for signal processing to pick out the meteors?
(Score: 0) by Anonymous Coward on Sunday December 01 2019, @02:42PM
someday soon stargazers will be able to complain on twatter about "starlink" ruined pictures from the middle of nowhere, really fast ^_^