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  1.  
    SpaceX launch imminent
    https://www.spacex.com/webcast?
    Let's play chase the fairings in broad daylight
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      CommentAuthorgoatcheez
    • CommentTimeJan 30th 2020
     
    Last summer, a secretive space company took up residence in a massive warehouse in the sun-soaked industrial neighborhood that surrounds Long Beach Airport. Reflections of turboprop planes flit across the building’s mirrored panes. Across the street a retro McDonnell Douglas sign perches above the aerospace giant’s former factory, and just around the corner Virgin Orbit is developing air-launched rockets.

    It’s a fitting headquarters for SpinLaunch, a company breathing new life into the decades-old idea of using giant mechanical slings to hurl rockets into orbit. The man behind this audacious plan is the serial entrepreneur Jonathan Yaney. For years he ran SpinLaunch out of a former microprocessor plant in Silicon Valley, down the road from Google. Now the company is ready to open a proper rocket factory, where it will churn out launch vehicles and, if all goes well, take its first steps into the cosmos.

    R
    • CommentAuthorAsterix
    • CommentTimeJan 30th 2020
     
    10 000 G? What could go wrong?
  2.  
    Everything?

    That's the kind of activity you'd want to put out in the desert, like at Mojave or Cal City, rather than in the middle of frigging LA Basin.
  3.  
    I bet Space Force can find a use for it
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      CommentAuthorAngus
    • CommentTimeJan 30th 2020
     
    200 pounds at 5000 mph works out to 2 GJ. About half a kilotonne. Sure hope it doesn't hit anything.
    •  
      CommentAuthorTrim
    • CommentTimeJan 30th 2020
     
    I thought it was supposed to be a scam?
    • CommentAuthorAsterix
    • CommentTimeJan 30th 2020
     
    It probably still is.
    •  
      CommentAuthorAngus
    • CommentTimeFeb 21st 2020
     
    I just ran across an interesting article on light sails in the February issue of Optics and Photonics. (It's an internal news mag for OSA, something like Spectrum for IEEE). It reminded me that if you reflect perpendicularly off a diffraction grating you would have both a perpendicular and a transverse force on the grating, the resultant depending on wavelength and grating period etc. So that would mean that if you had a diffractive structure on the light sail that was circumferentially periodic at a period of the order of a wavelength of the light, it would produce a component that would rotate the sail. There is no problem embossing such a thing on a plastic film. You can see almost the identical item on your credit card.

    This might give you a method to keep the sail from collapsing from the inward force of the guy wires. Or allow you to make a bigger sail for a given angle of pull.

    Brand new here. Moletrap gets if first.
  4.  
    Once the sail is rotating enough to keep the sail from collapsing, what then requires additional rotational thrust? Can't you just spin it up once and send it on its way in rotational equilibrium?
  5.  
    You can also get mechanical spin from polarisation, curiously enough.
    •  
      CommentAuthorAngus
    • CommentTimeFeb 22nd 2020
     
    Posted By: Andrew PalfreymanYou can also get mechanical spin from polarisation, curiously enough.


    Certainly, there is angular momentum in certain helically polarised beams.It does transfer to particles. I'm not sure how this transfers to a mirror on reflection though. With a grating there is a lateral component to the reflection that comes from the higher diffraction orders. I should have mentioned that you have to have blazed rulings on the grating so the negative orders don't cancel the positive ones.

    @Al. I had also thought of that little problem. It's like the rocketships in The Expanse - apparently their motors run all the time. You have to figure out how to shut the spinner off when you get to the right rotational speed. Maybe uncover a portion blazed the other way?
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      CommentAuthorTrim
    • CommentTimeFeb 22nd 2020
     
    Well done Angus.
  6.  
    •  
      CommentAuthorTrim
    • CommentTimeMar 12th 2020
     
    Who's been leaking all my ideas.

    Space tourism for the people: become a virtual reality astronaut.

    https://www.theguardian.com/science/across-the-universe/2018/may/17/space-tourism-for-the-people-become-a-virtual-reality-astronaut
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      CommentAuthorTrim
    • CommentTimeMar 12th 2020
     
    Posted By: Andrew PalfreymanNice little vacation spot
    https://www.theguardian.com/science/2020/mar/11/scientists-identify-rain-of-molten-iron-on-distant-exoplanet


    Where does the iron come from, it should all have precipitated on the cold side by now???
    •  
      CommentAuthorAngus
    • CommentTimeMar 12th 2020 edited
     
    The thing is a gas planet, so there is no fixed cold side. It remains above the melting point of iron all over because of heat transfer by the atmosphere. So the moleten iron flows back to the other side where it heats up and evaporates again. Nice place, as AP says.
    •  
      CommentAuthorTrim
    • CommentTimeMar 12th 2020
     
    Tidally locked, and what is the speed of sound in gaseous iron?
    •  
      CommentAuthorAngus
    • CommentTimeMar 12th 2020
     
    Depends on the pressure (says he stalling for time).
    •  
      CommentAuthorTrim
    • CommentTimeMar 12th 2020
     
    Google doesn't seem as good nowadays.