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From: Cryptoengineer <petertrei@gmail.com>
Newsgroups: rec.arts.sf.written
Subject: Re: OT: Surely there's an SF story with this.....
Date: Sun, 1 Sep 2024 14:16:07 -0400
Organization: A noiseless patient Spider
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On 8/31/2024 5:27 PM, Robert Carnegie wrote:
> To add to my previous comment, I think "The Brick Moon" (1869)
> considered the question of making an artifical moon bright.
> 
> The "magnitude" of the actual Moon is given as -12.7.
> 
> The magnitude of the ISS is "up to" -6.  I don't
> know if that's with guests staying.
> 
> I think Eandall Munroe wrote a thought experiment
> od illuminating the Moon with an awful lot of
> laser pointers.  It wouldn't be Randall if it
> ended well.

I remember that! OTOH, a strong laser pointer on the
Earth's surface can be seen from orbit, all going well.

But... back to the present.

The Moon as an albedo of about 0.12, which would
suggest that its about 1/(0.12) or 1/8 as bright as the
sun. But that doesn't take into account the scattering
of sunlight in all directions. Albedo 1.0 is white, not
a mirror.

The Soviets did try a 20 meter mirror, which very
briefly provided light on a rapidly moving 5km spot
on the ground, equivalent to 'several full moons'.

https://www.vice.com/en/article/the-man-who-turned-night-into-day/

So, yes, maybe you could provide a light with some usefulness
for a few minutes, if the mirror was steered to point to one
spot. Reflect Orbitals claim is that they can provide
light for 4 minutes at a time.

The ISS can be in sight for as long as 6.5 minutes on a pass, so
RO's mirrors must be lower. That's good for being bright, but also
means they're subject to a lot of drag from remnant traces of
atmosphere, and will need to either have propulsion to keep on
station, or be replaced frequently.

The suggestion to use RO's mirrors to power solar plants is a
total non-starter. The mirror can't deliver more light than
falls on it, and if its spread over several kilometers on the
ground, its just not bright enough to do anything useful, quite
aside from the idea that powering one for less than 5 minutes
has a use case.

Finally, you'd piss off every astronomer and stargazer on Earth.

pt