Author Topic: Episode #726  (Read 1940 times)

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Online bachfiend

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Re: Episode #726
« Reply #45 on: June 18, 2019, 12:38:34 AM »
The average albedo of the moon is only about 0.12 -- roughly the albedo of aged asphalt.  One might conceivably scatter high-albedo particulates to increase albedo by a factor of 2-3. It would not require full coverage, and it could be done with something as simple as water ice.  The result might be something like this:



For full effect, position yourself so that your thumb, at arms length, just covers the disk of the moon. A non-trivial effect, don't you think?

How much water would you need?  It costs around $10,000 to get 1 kg into low earth orbit.  How much would it cost to get a kg of water to the moon?  How much surface would it cover to be effective?  How long would it last before it evaporates and disappears?  You’d need something more permanent.  And actually as advertising it would only be effective around the time of the full moon.  A few days each month.

And the effect would be almost trivial.
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Offline daniel1948

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Re: Episode #726
« Reply #46 on: June 18, 2019, 11:16:10 PM »
Terraform the moon, plant rainforest over the whole near-side surface, then cut down greenery in the form of your logo, and salt it so no more plants could grow there.

Actually, I thought the idea was to shine a laser at it, not to create a permanent structure on the surface.
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Online bachfiend

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Re: Episode #726
« Reply #47 on: June 18, 2019, 11:22:24 PM »
Terraform the moon, plant rainforest over the whole near-side surface, then cut down greenery in the form of your logo, and salt it so no more plants could grow there.

Actually, I thought the idea was to shine a laser at it, not to create a permanent structure on the surface.

Well, your ‘suggestion’ is almost as feasible as the idea of spraying water on the Moon.

I don’t think a laser would work.  Not only would it have to be a very large (in order to create an image around 4000 km in length) and powerful, it would only work on the new moon, and the image would be lost in the glare of the day sky.
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Offline Fast Eddie B

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Re: Episode #726
« Reply #48 on: June 23, 2019, 10:42:57 AM »
About Who’s That Noisy...

I never would have guessed it. And I was a multi-engine flight instructor who taught prop synchronization.

The planes I instructed in were 1960’s, 1970’s and 1980’s vintage. None had automatic prop synchronization that I recall. But the sound of props out of synch was a far lower frequency throbbing than the sound presented. A BE99 is a turboprop, so that may be a factor, yet turboprop props are geared down to spin at roughly the same speed as piston props*, so I don’t think that’s the difference. In any case, that throbbing was nothing like that in the audio.


*If a prop turns faster than about 2,800 rpm - depending on diameter - the tips go supersonic, with hits to both noise and efficiency. So turbines and high-rpm engines need to be geared down to lower speeds.

 

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