Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Question about Heliopause / radio noise

  1. Jan 9, 2013 #1
    I'm writing a story that takes place at about 200 AU from Sol - it's outside the heliosheath, where solar wind and interstellar wind meet. We haven't managed to send any spacecraft that far out yet, though Voyager 1 and 2 will get almost that far before they run out of thruster fuel and energy in 2020 or so.

    I'm not clear on how much difficulty there would be in communicating with Earth from this location - not simply the considerable distance, but the termination shock or bow shock (where solar wind and interstellar wind collide) which produce a low-frequency signal that's been estimated at 10 trillion watts.

    So, any ideas what difficulties there would be in communicating from this location to Earth, assuming average solar activity (no unusual sunspot activity or solar storms)?

    Stray Catalyst
  2. jcsd
  3. Jan 9, 2013 #2


    Staff: Mentor

    This wiki article has a paragraph on Voyager communications that may help.

    Specifically they upgraded the earth based dish antenna size to 270 feet to allow for fainter signals and they are working on a network of antennas for even fainter signals.

    They also mentioned bitflips in the computer memory so as you get into a more highly irradiated area then they may become too much to correct thus ending the mission.
  4. Jan 9, 2013 #3
    I'm reading the Voyager 1 wiki, but they only mention the 3.7m parabolic dish on Voyager 1, not any of the Earth-based (or near Earth orbit) equipment. Could you please post the link, so I can read the article you've mentioned?
  5. Jan 9, 2013 #4


    Staff: Mentor

    The link I posted is the link, look at the table of contents at the start of the article and click on 2.4 Communications.
  6. Jan 9, 2013 #5
  7. Jan 9, 2013 #6


    Staff: Mentor

  8. Feb 4, 2013 #7
    jedishrfu, thank you, that clears up a lot.

    However, I'm finding a lot of info about specifics on how the best technology of 1977 deals with this problem... without any clear explanation of the theories of how much radio noise is expected, or if it will be a problem at all.

    The distance will be no real problem. Transmitter and receiver will be easily able to find each other, so with the possible exception of times that the sun is in line with them, the distance is only going to add speed-of-light lag, and predictable signal strength loss (which can be solved with high gain antennas and other known technologies).

    The question I still have, and I'm not even sure where to start looking for information about it - is there likely to be difficulty in sending a signal through the heliopause (which, in some theories, is going to be a massive source of radio noise) without lots of redundancy, error correction, etc? The solar wind meeting the intergalactic wind, means interaction between a lot of high energy particles traveling at high speed in different directions, though the density is low. I used the Voyager 1 and 2 as examples, though they've only begun to reach the heliopause - my question is about communication from about twice as far out, at 200 AU (in theory, well outside of the heliosphere and into the bow shock).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook