Astronomy and space exploration

Discussion in 'General Discussion' started by eloyc, Apr 10, 2017.

  1. Sxotty

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    I dont know about that video, but it is true that they do not have a stellar record about worrying about negative externalities from their space activities. Times have changed since the 1970s in terms of expectations.
     
  2. zed

    zed
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    I believe what separates this from other pieces of space junk is its the largest in 30 years (hmm what about mir?, which I did try to see when it came crashing to earth early 2000s got up went to the beach in NZ looking north to hopefully catch a glimpse of it falling but saw nothing)
    Is they could of choose where to crash land it (usually in the south pacific away from land, there was a recent stuff you should know podcast about this IIRC) but they didnt, they choose to let it fall anywhere.
    The USA does stuff that I dont like eg musks lets triple the satellite count so we can have some internet for a few ppl around the world and has blown up a setlitte in the past (something that china done a couple of years ago)
     
  3. Sxotty

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    If it is the largest in thirty years then it is clear they care less than other countries and pretending otherwise is silly. BTW that was the last one they let fall randomly. It landed in ivory coast. Then they decided to do the same again. They also showed toxic residue all over their own people at launch though are changing that .
     
  4. hoom

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    Except its obviously not the biggest bit of space junk in 30 years.
    Mir was 129tons, Challenger 78, the Ivory coast booster was last year not 30 years ago.
     
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  5. zed

    zed
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    Yes I mentioned Mir, So I looked into it a bit more
    https://www.space.com/china-rocket-falling-from-space-dont-worry
    So I think what they are only talking about when they say largest in the last 30 years is in the 'deliberately gonna crash somewhere and we dont give a shit' category
    This is not picking on China cause its China doing it, if it was the USA or any other country it would be just as bad. Hoon if ppl don't protest about China doing this, then they will keep on doing it in the future, yes the odds of this hurting anyone are astronomically small, then again the one last year damaged human structures in the Ivory Coast, which is also very small (Im guessing human made structures make up way less than 1% of the planets surface)

    edit:
    https://en.wikipedia.org/wiki/List_of_reentering_space_debris
     
    #805 zed, May 8, 2021
    Last edited: May 8, 2021
  6. zed

    zed
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    Just a couple of hours to go.
    Mar largo is in the firing line :runaway:
     
  7. zed

    zed
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    Theyve lost track of it. should be over south spain in 15 mins Im gonna have a look outside, in the faint chance its there
     
  8. Davros

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    Debris from a large Chinese rocket, the Long March 5B, landed in the Indian Ocean near the Maldives, China’s space administration said.
     
  9. zed

    zed
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    yes disappointing I saw nothing, like mir 20 years ago (at least then I had beer), not sure how accurate the following is cause it most likely left debris over a path not just a specific point.
    I should of stayed in bed but one never knows, I did see that comet from a couple of months ago, that was lame, nearly as lame as haleys comet (nothing can top that for a lame space event)
    [​IMG]
     
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  10. pharma

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    Voyager spacecraft detects 'persistent hum' beyond our solar system (microsoftnewskids.com)
    May 12, 2021
     
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  11. zed

    zed
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    sound (unlike the electro magnetic spectrum) must travel through matter
    and yes there is about 1 atom per cm cubed in space but surely thats not enuf to transfer sound.

    I would assume they dont mean sound, but they mention a hum and sound hence my confusion?

    my theory is hendrix, Im not sure how, but its hendrix
     
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  12. nutball

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    If it's a plasma then the atoms are ionized and will couple with the local magnetic field. If I remember my Plasma Physics 101 basically what happens is that the motion of the magnetic field influences the motion of the ions, and the motion of the ions influences the motion of the magnetic field. So you can easily get oscillatory (wave-like) phenomena, which is kind of like sound but also kind of not.

    For a press release a "hum" is something most people will understand at some level.
     
  13. Davros

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    Do you know why interstellar gas hums ?
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    It doesnt know the words ;)- I'm here all week......
     
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  14. Sxotty

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    China landed a rover on Mars. More rovers more science, seems better to me.
     
  15. cheapchips

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    The different landing approaches between the US and China are interesting. China avoided the sky crane and landed a table with a ramp. Wonder where the mass trade off between the two is?

    The sky crane is presumably a bit more mass efficient but it's is barmy.
     
  16. Sxotty

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    That is how NASA used to do it with smaller rovers. But you know bigger is better :)
     
  17. cheapchips

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    Zhurong has better radar penetration than Perseverance despite being smaller. :-D
     
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  18. w0lfram

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    Question that will ponder you... can light create a venturi effect... if seen through the fluid dynamics of gravity...?
     
  19. Davros

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    If I'm understanding your question then the quick answer is no, because light wont accelerate
     
  20. Sxotty

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    Hey what about a superluminal boom, cherenkov radiation from particles exceeding the speed of light on a medium? Lights travels at 2.25E8 m/s in water an 3E8 in vacuum. How does it change speed if it doesn't accelerate :) also since it has no mass the acceleration would be infinite so instant change. But it is really absorbed by material and then re-emitted so that is less fun.


    The venturi effect is about changing energy I think, the speed increases so pressure goes down. Light changes frequency so energy is changing, but I don't know which other bucket that energy goes to in a given reference frame.
     
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