this post was submitted on 18 Sep 2024
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We could and should be doing both ground and orbital radio telescope observations. One really interesting idea I've seen floated is to put one on the far-side of the moon; it'd be shielded from all our radio emissions but, of course, it would be somewhat suspectable to interference from the sun for weeks at a time.
What I've never understood about Starlink is how it's better than existing satellite internet beamed from geosynchronous craft... like, geosync is crowded (especially over North America and Europe), but it's not so crowded we couldn't put a couple more transponders up there. Objects in geosync rarely have the astronomical side effects that Starlink is apparently causing. It would even solve the Starlink issue of having to have an expense af receiver with active tracking... just nail up a stationary ku-band dish that doesn't need to move ever. This is already solved technology.
The problem with geosynchronous orbit is that you need to be at a high altitude to maintain it. That increases the packet round trip time to a receiver on the ground. Starlink satellites orbit low enough to give a theoretical 20ms ping. A geostationary satellite would be at best 500ms. It’s fine for some tasks but lousy for applications that need low latency, like video calling.
Is there any way to improve that? Or is it a hard limit due to physics?
Unfortunately it’s a hard limit due to the speed of light. Theoretically you could use quantum entanglement to get around it, but then of course you wouldn’t need the satellites anymore.
no, you couldn't. You can't use quantum entanglement to send information. Only random noise.
Sorry, I meant theoretically as in “at some distant point in the future where we’ve figured out how to make it work.” I probably read too much science fiction.
it physically cannot work. ever. That's just how entanglement works. We know that much.
That's not true either unfortunately
Science fiction quantum entanglement is not the same as real life quantum entanglement. Science fiction has spooky action at a distance, real life doesn't.
The speed of light is the speed of causality, the speed of information. It is physically impossible to send information at speeds greater than the speed of light.
In real life, all quantum entanglement means is that you can entangle two particles, move them away from each other, and still know that when you measure one, the other will have the opposite value. It's akin to putting a red ball in one box and a blue ball in another, then muddling them up and posting them to two addresses. When opening one box, you instantly know that because you saw a red ball, the other recipient has a blue one or vice versa, but that's it. The extra quantum bit is just that the particles still do quantum things as if they're a maybe-red-maybe-blue superposition until they're measured. That's like having a sniffer dog at the post office that flags half of all things with red paint and a quarter of all things with blue paint as needing to be diverted to the police magically redirect three eighths of each colour instead of different amounts of the two colours. The balls didn't decide which was red and which was blue until the boxes were opened, but the choice always matches.
The geosynchronous satellites are about ~~650~~ 65 times higher than Starlink satellites, so the speed of light is a significant limiting factor.
Geosynchronous orbit is 35,700 km (3.57 x 10^7 m) above sea level. At that distance, signals moving at the speed of light (3.0 x 10^8 m/s) take about .12 seconds to go that far. So a round trip is about .240 seconds or 240 milliseconds added to the ping.
Starlink orbits at an altitude of 550 km (5.5 x 10^5 m), where the signal can travel between ground and satellite in about 0.0018 seconds, for 3.6 millisecond round trip. Actual routing and processing of signals, especially relaying between satellites, adds time to the processing.
But no matter how much better the signal processing can get, the speed of light accounts for about a 200-230 millisecond difference at the difference in altitudes.
Thanks! That's the shit for which I come to Lemmy. Genuinely, thank you.
I work in broadcast communications and we use geosync link ups all the time for various shit. I'm pretty sure I know more about satellite communications than a normie, but I'm blind to the intricacies of use case when it comes to stuff like this.
In the past 6 months, Starlink satellites made 50,000 collision avoidance maneuvers. They now maneuver 275 times a day to avoid crashing into other space objects.
They use an on board AI to calculate the positions, but each time they course-correct, it throws off forecasting accuracy for several days. So a collision isn't an if, it's a when, and suddenly we're in Kessler Syndrome territory. Or maybe enough people will eventually wake up and realize Musk was an actual idiot all along.
But until then, great, low pings for video calls. Hurray.
This is completely factually inaccurate. 2 minutes on Google will help you learn but seeing as how you’ve been spewing crap all over this thread I don’t think it’s worth my time to even bother helping you understand.
Can you debunk it for the rest of us?
Shortest answer is that even if all Starlink satellites suddently exploded at the same time for no reason, they'd fall back to Earth in a matter of weeks. They're waaaay lower than the other satellites you're thinking of (see discussion on geo-stationary satellites for why), so they need to be actively pushed every few days just to stay up. They're so low they're still subject to atmospheric drag.
They would fall to earth in pieces? Is that an alright thing?
They'd burn up / vapourize. This is partly why it took them so long to get their space lasers to work (for satellite to satellite communications); these things usually are usually based on a crystal that wouldn't burn and could hurt someone when the satellite falls.
Well it can't have no effect can it? Maybe not safety but pollution?
Man, you really are looking for any excuse to hate on SpaceX, right?
If you're that worried about pollution, just look up the mass of a starlink satellite vs the mass a coal plant burns every hour... Even if the satellite ends up vapourizing as 100% pollution, I'm pretty sure it's orders of magnitude below other industries like coal power or aviation.
Sure asking questions is making excuses to hate SpaceX.
Is it polluting or not? I actually expected you'd show it wasnt at all. I literally don't know either way but if you aren't comfortable explaining your position on it thats fine.
"Just asking questions"... It's just a bit suspicious that as soon as the safety aspect was proven to not be an issue, you immediately switched to another angle.
But to answer your question, yes, vapourizing someting made of metal and plastics in the upper atmosphere could certainly count as pollution, and we don't really know the effects it might have on it because no studies have yet been done.
What has been done, though, is a study of how many meteors fall on the earth every hear: early estimates in the 60s were of about 100,000 tons per year, but further studies (1) showed this was grossly underestimated and more accurate values would be about triple that.
Starlink has launched 6,054 satellites in orbit (2) that total about 3,838,042 kg or a bit below 4000 tons. Even if they all fell in the atmosphere tomorrow, it'd only amount to less than 2% of this years' "stuff" that burns up in the atmosphere (the rest coming from natural sources). Honestly I don't think that's significant, but I'll concede that we don't really know for sure. I just think that there are other more immediate, much worse sources of pollution that people should direct their anger towards.
1: https://web.archive.org/web/20110512174406/http://static.icr.org/i/pdf/technical/Moon-Dust-and-the-Age-of-the-Solar-System.pdf 2: https://en.wikipedia.org/wiki/List_of_Starlink_and_Starshield_launches
Noones angry here, and I have room in my brain to consider more than one thing of course. I get nothing from starlink so I'm mainly interested in the positives vs the negatives. I have heard the positive side a bunch, not the negative side. I do wish the answer was a bit more than "we don't know yet", but I'm not going to say that starlink shouldnt exist.
I've personally been a Starlink subscriber for about a year while I was traveling, and it really was a game-changer. Rock-solid internet in remote places, fast enough to have Zoom calls on, all for a price that's only about twice what I currently pay now that I'm back home (people complaining about Starlink's price don't know what they're talking about, this is 100+ Mbps statellite internet we're talking about. Other options are ten times the cost for less than a tenth of the speed).
It just drives me nuts when I see progress being blocked for stupid reasons. Examples in other areas would be wind power ("but what about the birds"), electric cars ("but cobalt = slave labour", "akschually, when you charge the car with the dirtiest fuel possible and take into account all externalities it's less green than just the tailpipes of a gas car"), space exploration ("the potable water sprayed on the launch pad leaked into the environment, here's a fine"). There's some stuff that's been disproved years ago by anyone with half a brain that keeps being repeated, it's infuriating.
Okay and what about how you use starlink is a benefit for society? I understand it benefits you personally.
What are you hoping starlink is going to help us progress towards?
Connecting more people to the Internet, giving more options in rural areas.
Search the web for “star link Kessler syndrome”. It’s well documented. It’s also discussed elsewhere in this thread.
Cite sources please?
Search the web for “starlink Kessler syndrome”. It’s very well documented. It’s also discussed elsewhere in this thread.