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  1. - Top - End - #31
    Barbarian in the Playground
     
    PaladinGuy

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    Default Re: Interplanetary Internet

    Quote Originally Posted by DeTess View Post
    What makes you think that laser would have a shorter delay than radio? Those waves move at the same speed.
    I think the "6 minutes" is the same for both. But Laser as higher frequency can fit more information in, and can be more directed (so energy efficient).
    So Radio would be longer than 6 minutes as you're waiting for it to get to the front of the queue and for a big file for the end to catch up with the start (compare 1G and 5G same radio speed...)

    Some form of (magical) really low density FTL communication would add an interesting additional layer (high density would just be boring).

  2. - Top - End - #32
    Halfling in the Playground
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    Default Re: Interplanetary Internet

    Quote Originally Posted by DeTess View Post
    What makes you think that laser would have a shorter delay than radio? Those waves move at the same speed.
    If I understand tvtyrant correctly, he is saying that laser communication would have less issues with the 6 minutes ping time than other forms of communication have.

  3. - Top - End - #33
    Bugbear in the Playground
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    Default Re: Interplanetary Internet

    Quote Originally Posted by jayem View Post
    I think the "6 minutes" is the same for both. But Laser as higher frequency can fit more information in, and can be more directed (so energy efficient).
    So Radio would be longer than 6 minutes as you're waiting for it to get to the front of the queue and for a big file for the end to catch up with the start (compare 1G and 5G same radio speed...)

    Some form of (magical) really low density FTL communication would add an interesting additional layer (high density would just be boring).
    Well, the absolute maximum data rate you can get is B*log2(1+S/N)
    where B is the literal bandwidth (amount of frequency you are modulating) and S/N is the signal to noise ratio.

    So assuming the laser is within the visible range, you'd get about 300THz to play with. In reality, there is simply no known way to modulate any signal that quickly, but who knows (and then it wouldn't be a "LASER" it would be "optical signal directly coming from an D/A converter"). Lasers get their advantages from propagating through (and being separated by) fiber optic cables: it isn't clear that a sufficiently high frequency signal would be any slower.

    PS: to get the "maximum data rate" you also have to do an amount of calculation that approaches infinity, and send data for an infinitely long time to get B. To get extremely close still takes significant time, but far less than 6 minutes. Expect to see some sort of "Shannon level ECC" (the level determined by the equation above).

  4. - Top - End - #34
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    Lizardfolk

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    Default Re: Interplanetary Internet

    Quote Originally Posted by DeTess View Post
    What makes you think that laser would have a shorter delay than radio? Those waves move at the same speed.
    Being an idiot mostly. I figured the longer wave lengths would travel slower, and would be more prone to lost information due to lower frequency. Of the many subjects I don't know about, this is the subject I know least about.
    Quote Originally Posted by The Glyphstone View Post
    Vibranium: If it was on the periodic table, its chemical symbol would be "Bs".

  5. - Top - End - #35
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    BlackDragon

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    Default Re: Interplanetary Internet

    Quote Originally Posted by Tvtyrant View Post
    Being an idiot mostly. I figured the longer wave lengths would travel slower, and would be more prone to lost information due to lower frequency. Of the many subjects I don't know about, this is the subject I know least about.
    You may be thinking of the fact wavelength and frequency are related by the equation freq x wavelength = c, and just getting the equation a bit mixed up? Longer wavelength means lower frequency, that much is true, but the wave propagation speed is still c.

  6. - Top - End - #36
    Titan in the Playground
     
    Lizardfolk

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    Default Re: Interplanetary Internet

    Quote Originally Posted by factotum View Post
    You may be thinking of the fact wavelength and frequency are related by the equation freq x wavelength = c, and just getting the equation a bit mixed up? Longer wavelength means lower frequency, that much is true, but the wave propagation speed is still c.
    It's dumber then that, believe me. I based it on the degrading frequency over distance due to space expanding, which I read in a book a full decade ago (ugh I feel old) and assumed that if the expansion of space lengthened wave length that the waves got slower. It all made perfect sense in my head, very distant star light becoming radio waves and how radio waves on Earth travel slower so radiowaves in space must be slowed down by gravity more. Self-reinforcing nonsense
    Quote Originally Posted by The Glyphstone View Post
    Vibranium: If it was on the periodic table, its chemical symbol would be "Bs".

  7. - Top - End - #37
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    Imp

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    Default Re: Interplanetary Internet

    Most likely Earth and Mars would not stream all of the new/updated content but just an index + change datetime of the data. You get an index of information that is between 8 and 40 minutes old. Then requesting any specific information takes 16 to 80 minutes since your request has to go to the other side first.

    Caching of data would potentially reduce it since a) when the data reaches the other side you have at least that and b) if someone else requests the data right before you do you can just piggy back on their response. All popular data would at least be 8 to 40 minutes old, all unpopular data would be at most 16 to 80 minutes old.
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  8. - Top - End - #38
    Halfling in the Playground
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    Default Re: Interplanetary Internet

    Quote Originally Posted by Mastikator View Post
    Most likely Earth and Mars would not stream all of the new/updated content but just an index + change datetime of the data. You get an index of information that is between 8 and 40 minutes old. Then requesting any specific information takes 16 to 80 minutes since your request has to go to the other side first.

    Caching of data would potentially reduce it since a) when the data reaches the other side you have at least that and b) if someone else requests the data right before you do you can just piggy back on their response. All popular data would at least be 8 to 40 minutes old, all unpopular data would be at most 16 to 80 minutes old.
    But if I understand correctly internet protocols are not a one-way trip. Loading this forum page, for example, would seem to require at minimum 8 trips between my computer and the GITP server (1. I ask GITP for a security certificate 2 GITP sends its security certificate 3. I asks a security authority to verify the cert 4. the security authority responds 5. I tell GITP I now trust it 6. GITP sends me the connection info 7. I tell GITP what data I want 8. GITP sends the data). If anything goes wrong the retries will consume even more time.

    So a 40 minute lag can quickly turn into waiting hours for a pageload. That's why I was thinking in terms of daily downloads of urgent content and monthly deliveries of hard drives for everything else.
    Last edited by Hyoi; 2020-07-09 at 09:37 AM.

  9. - Top - End - #39
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    BlackDragon

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    Default Re: Interplanetary Internet

    HTTP is a poor example of a protocol for this. For a start, every single image on a page has to be requested and downloaded separately. This is why the caching server would have to grab the images at the same time as the main page, or else it would potentially take *days* to check out a single Web page!

  10. - Top - End - #40
    Bugbear in the Playground
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    Default Re: Interplanetary Internet

    Honestly I don't think there would be much reactive caching going on. Big services would completely mirror their sites and exchange data in the background automatically. Things to small for might be mirrored by some bigger service (or at least static versions of them) but if they aren't I doubt they would have any relevance to normal internet use. Sometimes things might be specifically requested (how automatic that is depends on how much bandwidth is available) because you can't find the stuff locally or on bigger sites and that would then be cached too I guess, but the communication to get it from earth would probably be server side. I think most user side traffic between planets would be direct communication and not website related and people would mostly just use the local internet.
    Last edited by Ibrinar; 2020-07-09 at 11:50 AM.

  11. - Top - End - #41
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    ElfRangerGuy

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    Default Re: Interplanetary Internet

    Quote Originally Posted by Tvtyrant View Post
    Being an idiot mostly. I figured the longer wave lengths would travel slower, and would be more prone to lost information due to lower frequency. Of the many subjects I don't know about, this is the subject I know least about.
    From how I understood it, the shorter wavelengths can carry more information, but are more prone to disruption, while the longer wavelengths it's the other way around. That's why the US and some other countried for instance have (or had, as some are now not used anymore) a huge antenna to talk to its submarines. It has an extremely low frequency as that is the only way to actually go underwater, but it can only send very limited communication. Mostly they use it to send a few letters to the sub which is a code for something (mostly to come up and hook up to a satellite for the real message).

    https://en.wikipedia.org/wiki/Commun...ith_submarines
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  12. - Top - End - #42
    Bugbear in the Playground
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    Default Re: Interplanetary Internet

    Quote Originally Posted by Tvtyrant View Post
    Being an idiot mostly. I figured the longer wave lengths would travel slower, and would be more prone to lost information due to lower frequency. Of the many subjects I don't know about, this is the subject I know least about.
    I mean, in space I think it should be fine either way (although I don't really know much about astrophysics, so maybe I'm ignoring important interference considerations from background radiation), but lower frequencies are actually less lossy if they pass through media. Skin depth is proportional to wavelength, which is why any sort of sensing through very lossy media, like SONAR through water, will rely on very low frequency waves.

    As farothel said, higher frequencies can give you higher sampling rates, so I think that in general they can carrier more information, all else equal. However, there's a ton of interesting and creative things they can do in signal analysis (most of which the math is beyond me) that you can do to optimize the signal. In terms of how much rate of information transfer you would need to keep the "important" (commonly used?) bits of the internet updated between two worlds, I don't know whether signal bandwidth would become the limiting factor. In terms of current internet architecture, as I understand it there is already substantial mirroring and redundancy that is largely governed by algorithms meant to optimize efficient access. Adding in a step with 6 minute latency wouldn't be trivial, but I don't think it would require any revolutionary leaps in technology to optimize for that added step.
    Last edited by Xyril; 2020-07-13 at 06:20 PM.

  13. - Top - End - #43
    Titan in the Playground
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    Default Re: Interplanetary Internet

    1. We do not have the technology to do this.

    2. We do not have any motive to develop the technology to do this.

    3. The internet is a very new development, changing rapidly at all times.

    4. By the time there is any need to do this, internet technology will be unrecognizable to us today.

    Trying to answer this question today is like trying to design a Saturn V rocket the day after Kitty Hawk.

  14. - Top - End - #44
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    Rockphed's Avatar

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    Default Re: Interplanetary Internet

    Quote Originally Posted by Lvl 2 Expert View Post
    I'm not a physicist, but as far as I know the current understanding is that it can't be done. There is no way to send any information through quantum entanglement without another supporting data stream. It's not a single bit per entangled pair or something like that, it's actually zero bits of useful data.

    Basically measuring the state on one end tells you what the state on the other end was at that exact same time, but the state on both ends is random, there is no way to set the state without breaking the link. Possibly useful for cryptography, but not for sending information faster than light.
    Quantum Entaglement is great for generating crypto, but sending real data is not possible. I remember a talk at school about how they were generating crypto with quantum and had made a quantum crypto that worked for people some 500 km apart (which was some sort of record).
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  15. - Top - End - #45
    Barbarian in the Playground
     
    PaladinGuy

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    Default Re: Interplanetary Internet

    Quote Originally Posted by Jay R View Post
    1. We do not have the technology to do this.

    2. We do not have any motive to develop the technology to do this.

    3. The internet is a very new development, changing rapidly at all times.

    4. By the time there is any need to do this, internet technology will be unrecognizable to us today.

    Trying to answer this question today is like trying to design a Saturn V rocket the day after Kitty Hawk.
    I don't think it's really Internet (communcation) technology that we are lacking, the issues with Mars are the issues they had with early internet. That side we've pretty much done, We've already adapted to sending data by truck, slow communciation networks, across broken communication networks, and even if only for a joke by pigeon.
    Developments are if anything going the wrong way based on vast convenient rates of data flow. Implementing it is slightly different but the problems seem solved, the problem is that 3&4 are true, and that will create new problems.

    Actual long range radio, or physical delivery, we technically do have (we could send the little rover, we could talk to the little rover), that's proved we have all we need, but it's a bit rubbish (I'm not sure what the data rates* are but I'm guessing a lot worse than 2G shared for the whole planet, and billions of £ to send, admittedly probably Petabytes, with months lag) so rounding that down, then all your points apply exactly.

    *256kbps for 8 minutes a day that's much better than I was expecting.

  16. - Top - End - #46
    Titan in the Playground
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    Default Re: Interplanetary Internet

    Yup . Trying to figure out how mass communication to Mars will be handled in the next century, based on current internet technology, is like people in 1861 trying to figure out how the pony express will work in 2020.

  17. - Top - End - #47
    Dwarf in the Playground
     
    Imp

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    Default Re: Interplanetary Internet

    This feels like a new problem, but it actually isn't. The larger companies already operate on a much more local level than generally realised. When real-time data is required you will obviously get at least the one way time latency, but when you connect so something like youtube you are already connecting to a fairly local mirror. Cloud hosting of websites means that even smaller sites behave like this now, and even if it didn't many ISPs would have their own cache of data that doesn't seem to change, and check with the server whether it has changed, before getting it fresh if required. It is already cheaper to host often requested data closer to users than transmit it over long distances repeatedly.

    The abstract model that you are talking to a single server in a single place is a good starting point for understanding internet services, but in truth there are already magic tricks going on. The problems have already been solved.

    As for data rates, they are going to be less limited than you might expect. It will be a question of how cheap we can mass produce good mirrors, and how large they can be, and how light. A 1m mirror can resolve ~50km at max distance in blue light, which seems like it would be limiting, but if you can launch deep space satellites from mars cheaply, and basically have a cloud of them in solar orbit, you get a huge number of potential paths. Putting them against the background of deep space means you don't even need to worry much about sunlight reflections (or Mars being behind the Sun), meaning they don't even need to be particularly powerful. Satellite internet is almost commercially viable on earth with current tech, and communications with Mars are not massively more complicated. Launching from Mars means it could actually be easier than getting to LEO.

    It will look like it 'just works', while there are engineers frantically paddling under the water to maintain the illusion. No different from the current internet.

  18. - Top - End - #48
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    Planetar

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    Default Re: Interplanetary Internet

    Out of interest, if you did want to guarantee a link was always available between Earth and Mars, i.e. get over the phenomenon of other celestial bodies blocking direct line of sight between the two planets, how would one do that? Bunch of comm satellites orbiting the Sun, picking the point based on future extrapolation of planetary orbits?

  19. - Top - End - #49
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    ElfPirate

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    Default Re: Interplanetary Internet

    Quote Originally Posted by Saintheart View Post
    Out of interest, if you did want to guarantee a link was always available between Earth and Mars, i.e. get over the phenomenon of other celestial bodies blocking direct line of sight between the two planets, how would one do that? Bunch of comm satellites orbiting the Sun, picking the point based on future extrapolation of planetary orbits?
    Yes basically. You'd want a "ring" of comm satellites in an orbit a bit like the GPS sattelites orbiting earth. Since the orbits are all known I guess the trick is to find where to put them where they do most good. My first thought is in an orbit between earth and mars but that might not be the best solution.

  20. - Top - End - #50
    Barbarian in the Playground
     
    MindFlayer

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    Default Re: Interplanetary Internet

    It should probably suffice to have one relay orbiting the sun at the earth-sun L4 or L5 point. That would always be well clear of any interference from the sun, and anything in the solar system should be visible either directly from the earth or from the relay. Possibly objects very close to the sun would need another relay, in which case you might need to use both L4 and L5. In fiction there was a bunch of stories set on a venus-sun L4 or L5 point "Venus Equilateral".

  21. - Top - End - #51
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    DwarfClericGuy

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    Default Re: Interplanetary Internet

    Quote Originally Posted by snowblizz View Post
    Yes basically. You'd want a "ring" of comm satellites in an orbit a bit like the GPS sattelites orbiting earth. Since the orbits are all known I guess the trick is to find where to put them where they do most good. My first thought is in an orbit between earth and mars but that might not be the best solution.
    Putting a ring of relays in the 'midpoint', so that no matter where the two celestial bodies were in relation to one another, the shortest path would be available - probably the best plan. Signal processing variable. For more reliability, you'd have multiple rings ... but...

    The main issue would be maintenance and replacement, but by the time we figured out the 'establish viable colony on Mars' thing, we'd probably have the whole spaceflight thing more or less figured out.

    Comm satellites work for a long time - it's usually the orbital decay that gets them. And geosynchronous satellites? They last pretty long.
    Last edited by sihnfahl; 2020-09-02 at 09:24 AM.
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  22. - Top - End - #52
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    Telok's Avatar

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    Default Re: Interplanetary Internet

    Quote Originally Posted by DavidSh View Post
    It should probably suffice to have one relay orbiting the sun at the earth-sun L4 or L5 point. That would always be well clear of any interference from the sun, and anything in the solar system should be visible either directly from the earth or from the relay. Possibly objects very close to the sun would need another relay, in which case you might need to use both L4 and L5. In fiction there was a bunch of stories set on a venus-sun L4 or L5 point "Venus Equilateral".
    For full redundancy and long term I'd put a comm sat in both of the Earth and both of the Mars L4s &L5s. You likely only truely on need the Mars ones as they're easier to launch & service from Mars. If you lack the infrastructure to build & launch them from Mars then the only difference between Earth L points and Mars L points is travel time.
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  23. - Top - End - #53
    Troll in the Playground
     
    Kobold

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    Default Re: Interplanetary Internet

    I see it as two separate internets, but with plenty of traffic between them. 40 minutes isn't that long, really. There'd be nothing to stop someone on Mars from posting a message on a Terran site, provided they didn't mind the delay - and, although a lot of people do expect instant feedback, a lot don't. Depends on context.

    Bandwidth, schmandwidth - that's exactly the kind of issue that technology will solve, sooner rather than later. Latency is another matter.
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