Re: Solar Shell



On Jan 27, 12:24 am, vinc...@xxxxxxxxxxxxxxx (pete) wrote:
on 26 Jan 2007 08:52:06 -0800,Willie.Moo...@xxxxxxxxx sez:





On Jan 21, 6:34 pm, jsav...@xxxxxxxxx wrote:
Williamknowsbest wrote:
The surface gravity of the sun is 27.9 gees.

An object held at a radius of 3.68 million km above the solar center
would feel a 1.0 gee force directed toward the sun.That is interesting.

If it were possible to reduce the output of the sun to about 0.24% of
its current output at peak, and make it a variable star with a 24 hour
period,But I think that is too ambitious.

Let us consider something more modest, which does not involve
re-engineering the Sun.

How about a sphere around the Sun with many openings, and which on the
bottom is coated with a reflective surface more than 99.76% effective?
Mirrors reflect a tiny fraction of the sunlight to reflect back on the
people living on the framework, held by the Sun's 1g gravity, and these
can easily be given a 24 hour cycle.

This is still an incredibly vast undertaking, for the far distant
future, but at least it doesn't involve re-engineering the Sun.

John Savard
I was thinking about your idea here this morning. The orbital ring
superstructure would form a mesh and could be made highly reflecting.
So, if it obstructed say 0.1% of the surface area of the sphere, then
the openings between the lines of circulating materials could easily
transmit the remaining energy.
Making panels reflective would reduce the area available to the black
body radiator within - any opening whether it were looking at the
surface of the sun or not, would appear to be a black body surface.
Since energy per unit area is proportional to the fourth power of
temperature, the ratio of temps can be calculated.
Tshell/Tsol = (1/fraction open)^(1/4)
This new temperature would communicate itself to the sun, and it would
increase its radius to compensate for the change in temperature. So,
the sun would not remain unaffected by a reflective shell of
non-radiating surface. (radiating surfaces are different)
So, if the open area were;
Open Tshel/Tsol Tshell radius-new
0.001 - 5.6 35,450K 21.9 million km
0.01 - 3.2 18,250K 3.2 million km
0.1 - 1.8 10,260K 2.1 million km
0.2 - 1.5 8,230K 1.6 million km
0.3 - 1.35 7,800K 1.3 million km
0.4 - 1.26 7,260K 1.1 million km
0.5 - 1.19 6,860K 1.0 million km
0.6 - 1.14 6,560K 0.90 million km
0.7 - 1.09 6,310K 0.83 million km
0.8 - 1.06 6,100K 0.78 million km
0.9 - 1.03 5,930K 0.74 million km
0.99 - 1.0025 5,784K 0.698 million km
1.0 - 1.00 5,770K 0.695 million km
So, the shell could consist of reflective material that had openings in
it. For safety, a large hologram spanning the line that intersect the
ecliptic would be equipped with a solar powered hologram that projects
light precisely at the same energy and color of today's sun throughout
the solar system.
We'll modify the sun in either case by building a substantial shell. A
shell only 1% populated with the reflective interior surface, would
hardly cause any change whatever - but still contain over 3,300 earth
areas!
So, this may be a place to start!
But since a shell of any size would change the sun anyway, and that
would have to be addressed as the shell was populated, then, there
would be pressure to break the sun up into parts that reduced its
output, since that increases its longevity.Did I miss the part where it was explained how we overcome the inherent
instability of solid structures around spheres at gravitational
scales? And splitting up a sun into a cluster must just make the
instability problems vastly worse.

--
==========================================================================
vincent@triumf[munge].ca Pete Vincent
Disclaimer: all I know I learned from reading Usenet.- Hide quoted text -- Show quoted text -

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Relevant Pages

  • Re: Solar Shell
    ... How about a sphere around the Sun with many openings, ... superstructure would form a mesh and could be made highly reflecting. ... the shell could consist of reflective material that had openings in ...
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  • Re: Solar Shell
    ... Not spherical shell structures in compressions. ... Which hold a sheet in tension against gravity ... At least as stable as the tidal motions on Earth due to the sun ... superstructure would form a mesh and could be made highly reflecting. ...
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  • Solar Shell
    ... The surface gravity of the sun is 27.9 gees. ... An object held at a radius of 3.68 million km above the solar center ... the sun and use those materials to construct a shell at this radius ... A dyson sphere has some 1,660x the area of this sphere, but it has ...
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  • Re: Solar Shell
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    (sci.space.policy)
  • Re: Solar Shell
    ... The surface gravity of the sun is 27.9 gees. ... The only way to do this is to split it into lots of small stars. ... a shell 4 million miles across. ... The total energy radiated ...
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