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B Oumuamua asteroid discussion

  1. Dec 13, 2017 #1
    Given the evidence available as of today, is it reasonable to believe there is even a miniscule chance that the Oumuamua asteroid was built by aliens? Or is this just sensationalist journalism?
     
  2. jcsd
  3. Dec 13, 2017 #2
    Please post a reference. I doubt any reliable sources are claiming it's alien built.
     
  4. Dec 13, 2017 #3
  5. Dec 13, 2017 #4

    davenn

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  6. Dec 13, 2017 #5

    OCR

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    Sure there is, it's a... Von Neumann probe !!


    And... that's absolutely true... !
     
  7. Dec 13, 2017 #6
    It's acting like a lump of rock following a trajectory easily undertood by Newtons mechanics.
    It's now on the way out of the the solar system., so if it were an alien craft, it's not particularly interested in visiting Earth,
     
  8. Dec 14, 2017 #7
    It's the end over end tumbling that is different than other space rocks. Also, it came from outside the solar sytem,looped past Earth and is now leaving the solar system.
     
  9. Dec 14, 2017 #8

    davenn

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    no it isn't, that isn't uncommon


    It actually looped around the Sun in a large hyperbolic path which confirms it's origin beyond the Solar System. Lots of asteroids and comets do farther and closer approaches to Earth. in this case the Earth was just a bit closer to one part of the orbit
    ... nothing unusual there
    closest approach to the Earth was 33 million km

    1280px-Oumuamua_orbit_at_perihelionsm.jpg


    Dave
     
  10. Dec 14, 2017 #9
    Seriously? There is NO comparison between a Solar System trajectory and an interstellar path. The only way this object could have approached us so closely is if there are billions of them out there. Adding in its unique light-curve and lack of volatiles makes it a worthy candidate for every possible telescopic investigation.
     
  11. Dec 14, 2017 #10

    Vanadium 50

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    Of course there is. The very message you are responding to is such a comparison.

    Yes. And? The number of such objects is measured in the quadrillions.
     
  12. Dec 14, 2017 #11
    Maybe it's just extremely wishful thinking on his part, but Stephen Hawking seems to think there's a chance this could be some sort of defunct alien probe.

    If a vast amount of resources were invested in this, would it even be possible to corral this thing and at least bring it into orbit around the sun?
     
  13. Dec 14, 2017 #12
    That statement is based on extrapolation from a sample of one - this object. You are probably right, otherwise this is an alien craft, but there are at least 3 properties here which no scientist would have predicted beforehand.
     
  14. Dec 14, 2017 #13
    According to this paper, the density of these objects should be higher than the density of comets in the Oort cloud.
     
  15. Dec 14, 2017 #14
    On the other hand here's a paper stating that the first interstellar object was significantly more likely to be an asteroid than a comet, so take your pick -

    https://arxiv.org/abs/1711.09599

    Some estimates suggest that 20,000 times more cometary material than asteroidal should be ejected. And yet we've never seen a comet not from the Oort cloud.

    Also yet another statistical oddity should not be underestimated : 'Oumuamua is remarkable for showing both negligible radial (U) and vertical (W) motion, while having a slightly sub-Keplerian circular velocity... any formation mechanism for this interstellar asteroid should account for the coincidence of 'Oumuamua's velocity being so close to the Local Standard of Rest' -

    https://arxiv.org/abs/1710.11364
     
  16. Dec 14, 2017 #15

    davenn

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    yeah, seriously !
    you should go do some reading before criticising
    A lot of unsubstantiated comments that are not even worthy of response :rolleyes::frown:
     
  17. Dec 14, 2017 #16

    Vanadium 50

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    No, it's not. I'd tell you how I did this, except that you seem to want to put your own spin on what I am saying. Sorry, I am not interested in that.
     
  18. Dec 17, 2017 #17

    sophiecentaur

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    A small object could be any shape and it would stay that way. A larger object (much larger) would eventually end up near- spherical due to its own gravity overcoming its structural strength.
    An object that small that was a highly polished sphere would be much more interesting and much more likely to be an artefact.
    A single sample of any shape would otherwise not be significant.
    Makes you wonder, though. WTF would we do about it is we actually detected intelligent signals coming from it?
     
  19. Dec 17, 2017 #18
    See if it responds to signals sent from Earth?
    Then again it's probably safer to build an armada of nuclear bombing spacecraft and try to destroy it,
    (It's the only way to be sure)
     
  20. Dec 17, 2017 #19
    Let me guess, this is an inferred reference to "Rendezvous with Rama" by Arthur C. Clarke, right? :woot::biggrin:

    Which was a very good book, even though nothing happens. :wink:
     
  21. Dec 18, 2017 #20

    sophiecentaur

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    It would have been cheaper to have turned off all our radio sources until it goes past! ("I don't think he spotted us.")
     
  22. Dec 20, 2017 #21
  23. Dec 20, 2017 #22

    mfb

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    Even with our current technology it would be trivial to spot signs of life on Earth from within the inner solar system. An image of the night side with sufficient contrast would work, a radio receiver would work, spectroscopy of Earth would see methane and oxygen as signs of life and couple of artificial compounds as signs of a civilization. We might be able to shut down the radio emissions, but not everything else.

    And we'll have much better technology long before we have the means to make interstellar trips, even at such a slow speed.

    If that would be an artificial object, "staying silent" wouldn't work.
     
  24. Dec 21, 2017 #23
    I also imagine that shooting a nuclear missile at it would be the equivalent of shooting an aircraft carrier with a bow and arrow.
     
  25. Dec 21, 2017 #24
  26. Dec 22, 2017 #25
    The asteroid is not that big. A nuclear weapon would most likely vaporize the 230 x 35 x 35 meter asteroid. Assuming it has an equivalent, or less, density than Earth. If the asteroid were to impact Earth and we could be assured that all the pieces of the asteroid after the nuclear blast were smaller than 20 meters in diameter, then that would be the way to go.

    A 20m diameter asteroid with 5.51g/cm3 density traveling at 50 km/s approaching the Earth at a 90° angle would begin to break up at an altitude of 48,900m (161,000 ft) and bursts into fragments at an altitude of 11,000m (36,200 ft.). The air blast would release 2.89 x 1016 Joules (6.89 MegaTons TNT) of energy. At a distance of 100 km the air blast will arrive approximately 5.08 minutes after the asteroid explodes in the atmosphere. The peak overpressure would be 987 Pa (0.14 psi) with a maximum wind velocity of 2.32 m/s (5.18mph) and have a sound intensity of 60 dB (heavy traffic). If you were directly beneath the air blast, the overpressure wave would arrive 47.2 seconds after the blast and peak at 14,700 Pa (2.09 psi) with a maximum wind velocity of 32.6 m/s (73 mph) and have a sound intensity of 83 dB (loud heavy traffic).

    Anything larger than ~20m (or denser than Earth) and there is a good possibility that it could reach the surface of the planet.
     
    Last edited: Dec 22, 2017
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