Transmitting to outer space

Discussion in 'General Science & Technology' started by Avatar, Nov 11, 2007.

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  1. TruthSeeker Fancy Virtual Reality Monkey Valued Senior Member

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    A liquid signal!?!?!?!?!? :bugeye:
     
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  3. Nickelodeon Banned Banned

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    I suppose anyone there will be bombarded with information emanating from our planet. You'd have to shout very loudly to be noticed.
     
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  5. Avatar smoking revolver Valued Senior Member

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    Do you think I'm some pseudosci seti idiot? I don't expect to contact anyone.
    Besides it won't be that kind of a signal.

    The biggest problem will be to get some amateur radio guy with a licence and radio equipment to help me, I don't want to buy a transmitter, because then I have to get a licence, and they ask lots of stupid things to get it, especially for such a powerful signal I have in mind.
     
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  7. Nickelodeon Banned Banned

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    Then just look up and shout. For all the good it will do.
     
  8. Vega Banned Banned

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    The signal would have to be embedded in a subspace wave, which I suspect would be in the form of an highly energetic exotic particle wave transmitter!
     
  9. Avatar smoking revolver Valued Senior Member

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    Nikelodeon: Look, forgetting all my artistic considerations, why do you think I plan to build an array of ridiculously powerful antennae if I didn't need a strong signal? :bugeye:
     
  10. kmguru Staff Member

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    You would need a high energy pulsed laser beam perhaps in the visible spectrum like blue or violet laser. By the time it reaches the intended location, it would have covered the entire planet. If the victims

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    at the other end would have sensitive receiving devices, they would know what to do.
     
  11. Avatar smoking revolver Valued Senior Member

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    The greatest concern for me now is to find a way to do it legally. I found out that in order to transmit the signal I have in mind I have to have an A class amateur radio licence, and there's no way I can get it easily and without becoming a radio freak.
    So now I'm considering two options - 1) Rent out our radio telescope at Irbene for one night; 2) Find some geek with an A class licence willing to help me.
    At the moment the first option seems more likely.
     
  12. Avatar smoking revolver Valued Senior Member

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    Of course there's also the thrid illegal option, but I don't wish to try that because I want it to be a public event. Curses!
     
  13. Avatar smoking revolver Valued Senior Member

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    However your idea of using a laser is an intriguing one, mostly because I wouldn't need a licence for that.
    I personally know the head of material physics institute of our Technical University and he's very into lasers, so perhaps they have such a powerful laser that I could use...

    At the moment I know nothing about laser communications, execpt that there are such, so I have to do the research. Thanks for the idea!
     
  14. Gustav Banned Banned

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  15. TruthSeeker Fancy Virtual Reality Monkey Valued Senior Member

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  16. Avatar smoking revolver Valued Senior Member

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    Why do you annoy me with your aliens?
     
  17. Nasor Valued Senior Member

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    I agree with some of the other posters who have pointed out that your requirements are ill-defined. You can "send a signal" that will reach Jupiter with your cell phone - just make a call, and your signal will pass Jupiter about 35 minutes later (assuming you time your call so that Jupiter is in the sky above you, otherwise your signal might be blocked by the Earth). Your cell phone probably puts out around .6 Watts of radio power, so by the time your signal reaches Jupiter (which is about 588 million km away) anyone on Jupiter will see a power density of around 5.5*10^-25 watts/ m^2. That's a (very) weak signal, but it's theoretically possible for someone to detect that signal and listen to your conversation if they have a sensitive enough radio telescope. And such an idea actually isn't that far-fetched; the Galileo space probe transmitted data back to Earth from Jupiter with a 15 watt transmitter, and NASA used a 70-meter antenna to pick up the signal. So how you send the signal really is a matter of how easy you want it to be for some hypothetical recipient on Jupiter to receive your message.
     
  18. Avatar smoking revolver Valued Senior Member

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    Thanks for the info! So 15w is enough too.
    I understand my requirements are ill defined, it's because both of my lack of knowledge in radio science as well as.. well.. no clear requirements. As you said, I'd like someone theoretically, but also realistically to be able to pick up the signal.

    So, what about using a laser pointer, would it be just as good as a radio for a signal?
    A 532nm laser with an output power of, let's say, 100mW - 200mW, or would 200-300 make a difference?
     
    Last edited: Dec 16, 2007
  19. kmguru Staff Member

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    You may need a Laser with a MW pulse...then you have to wait 8 to 12 years to get a feedback. Iam sure NASA is doing that for quite sometime and hoping to hit on a reply - unless they are laready in communication...

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  20. Avatar smoking revolver Valued Senior Member

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    I know that they are researching laser interplanetary communications, but nothing really functioning in place (read an article on this some time ago).

    The thing is that I don't need a feedback, I just need to send a signal realistically to Jupiter in a way that is powerful enough to be taken seriously as a possible way of communication:
    1) The signal has to be powerful enough to be theoretically picked up.
    2) It has to pass the Earth's atmosphere.

    The signal itself would be morse like.
     
  21. kmguru Staff Member

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    Then bundle several lasers together and connect all of them to one switch. Then you can use morse code and fire away. You can use a christmas light flasher and drive the circuit. That way, you can leave it on for days. Make sure you align using a telescope. But remember Earth and Jupiter move. So you may flash a few minutes before realignment unless you build a tracker
     
  22. Avatar smoking revolver Valued Senior Member

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    Wouldn't one 300mW laser suffice?

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    It costs $1700
    A 150mW ~ 200mW one costs $700.

    Would several such lasers increase the common strength of the signal?
     
  23. kmguru Staff Member

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    First of all, a 150 MW Laser may have a range of 50 miles where the laser will flare to about a meter in diameter, may be less. You have to check the spec.

    The idea of multiple laser is that if you focus all of them at the same point, then the intensity will multiply.

    Assuming the 300 mW can go all the way to Jupiter, the size of the dot could be the size of the Jupiter. You can calulate the size by calculating the size at 50 miles and extrapolating to Jupiter's distance. Now, if you take that 300 mW and spread it across Jupiter, you will get may be a 0.001 pico-watt per sqare-mile or less. So, that may be one photon reaching any detector there if the photon makes it and did not hit any debris on the way out.

    It is doable but may result in slightly above zero results at the other end. That is why, our signals to planets 4 light years away would not make much difference.
     
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