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I Thoughts on Breakthrough Starshot?

  1. Oct 28, 2016 #1
  2. jcsd
  3. Oct 28, 2016 #2


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    The "project" is at this point just a research project:

    They have a long way to go before such a thing will even be possible, much less feasible:
    "According to The Economist, at least a dozen off-the-shelf technologies will need to improve by orders of magnitude.[18]"

    Doesn't sound very realistic to me.
  4. Oct 28, 2016 #3


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    The problems with light sails are myriad and have been well publicized. See https://www.inverse.com/article/14246-5-big-questions-about-the-starshot-nanocraft-technology for discussion on some of these issues. It still looks like wishful thinking [emphasis on the wish part] to me. The concept appears feasible and probe costs could be manageable, but, the power issue still looms large: where will the trillion dollars for the laser come from?
  5. Oct 28, 2016 #4
    Do you think a more durable craft equipped with a "slow burning" rocket thrust would be more feasible?
  6. Oct 28, 2016 #5
    If 'feasible' means could it be done, then yes,
    but then we are back to the problem that it would take decades to go the nearest star system.
    Centuries to go anywhere that is seriously interesting.
  7. Oct 28, 2016 #6
    but if accelerated over a long period of time it could still reach a pretty fast speed.
  8. Oct 28, 2016 #7
    Yes, but since it's going fast when it gets to the destination there isn't much time to collect interesting data.
    The New Horizons probe though managed to collect a big set of data in a couple of days while passing through the Pluto system.
  9. Oct 28, 2016 #8


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    I think the idea is severely constrained by energy demands. I have zero faith we could build, much less sustain a device of such power. The economics and politics just do not work for me.
  10. Oct 29, 2016 #9


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    Another nutty idea. What power lasers and where are they located? On orbit? Problems with dispersion over 'long' distances. Sending back information from 4+ light-years away would seem infeasible. I would think a local star's radiation (and solar wind) would swamp any signal generated.

    Statements like ". . . , sending back pictures of anything interesting once it arrived," are just silly.
  11. Oct 29, 2016 #10
    is that due to the low momentum-energy ratio of light?
  12. Oct 29, 2016 #11


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    The logistics and economics of building and powering a 100 gigawatt laser array would be enormous. And, as already noted, how will the probe transmit its data back to earth? I'm unaware of any technology, real or imagined, capable of such a feat. We aren't talking about a light day here, as in the case of the solar system, we are talking 4 light years. Bear in mind signal strength falls by the square of distance.
  13. Nov 1, 2016 #12
    The earth bound laser would be one of the minor problems. Traveling at 0.2 c, even a dust particle could cause major damage to a probe. If the probe were to reach Proxima Centauri the path loss for the transmission, assuming a transmit gain of 10 dB and a receive gain of 40 dB would be 292 dB. http://www.qsl.net/pa2ohh/jsffield.htm With a receive sensitivity of -130 dBm it would still need a transmit ERP of 162 dBm or 10^13 watts using a frequency of 74 MHz for minimum path loss. A power supply capable of supplying that amount of power would also be needed. Inasmuch as the probe would already have to have a power supply that large, it might as well be used to propel the probe with a laser pointed backwards. Nevertheless the probe would have a mass of many thousands of tons. Then there is the problem of dissipating that much heat in a vacuum.
  14. Nov 1, 2016 #13
    A very good point, and whilst not actually plausible, that concept eliminates some modes of power wastage.
  15. Nov 1, 2016 #14
    I've always had a vision of a ring-like ship that has a powerful center generator that creates its own power, by simply rotating rapidly, causing electricity and immense power. The only time any other source needed would be on take off and landing.
  16. Nov 1, 2016 #15
    Simply rotating does not generate power.
    To generate electricity you need to be rotating in a magnetic field which itself is not rotating.
    Last edited: Nov 1, 2016
  17. Nov 2, 2016 #16
    Sorry, rotating was just the best word I could find to describe what I meant. Thanks for the clarification.
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