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From: beslove@osu-eddie.UUCP (Adam Beslove)
Newsgroups: net.space,net.physics
Subject: Re: ultralight probes
Message-ID: <352@osu-eddie.UUCP>
Date: Sat, 1-Jun-85 08:12:50 EDT
Article-I.D.: osu-eddi.352
Posted: Sat Jun  1 08:12:50 1985
Date-Received: Tue, 4-Jun-85 05:31:27 EDT
References: <5630@utzoo.UUCP> <9883@rochester.UUCP> <3169@dartvax.UUCP>
Reply-To: beslove@osu-eddie.UUCP (Adam Beslove)
Organization: Ohio State Univ., CIS Dept., Cols, Oh.
Lines: 43
Xref: watmath net.space:4084 net.physics:2533

In article <3169@dartvax.UUCP> chuck@dartvax.UUCP (Chuck Simmons) writes:

>> ...has anyone considerred the possibility of building
>> a lightsail out of photo-electric material?  

There will be a large energy loss due to the inefficiency of present
photo-electric materials.  A recent break thru of 12% efficiency rings a
bell, but I'm not certain.

>Would it be possible to design a "fabric" consisting of carbon or silicon 
>atoms with various other kinds of atoms in between.  The result would be 
>a molecule (in much the same way that a polymer is a molecule, except in 
>two dimensions) a few atoms thick.  A well-designed fabric might contain
>many itty-bitty holes, thus decreasing the density even further.
>
>*sigh*  Maybe if I don't think about the problem of making a square sheet
>of this fabric measuring a kilometer on a side, it will go away.
>-- Chuck

Assuming this sail would need to be assembled in space from terrestrial and
extra-terestrial raw materials, the fabric idea makes sense.  These
materials can be extruded thru laser cut holes into a continuous thread,
then densely woven into sail material.  This material can then be stretched
to it's desired size.  Extrusion makes weaving easy in 0 g's, just aim,
shoot, and stop flow after x meters have been extruded.  The stuff will
solidify pretty fast, too. With extruders on the x and y axis, weaving and
extruding could take place simultaniously.

The dimentions of the sheet wouldn't be tough, as the extrution equipment
would be mostly insulated piping and could be designed modularly.  Increase
in sail size could be accomplished by addition of extrution modules to the
loom. 

A problem I see with extrusion is regulating thread width.  Am I wrong to
assume that even if you extrude out of a very small hole, the stream will
thicken a bit before it hardens?  Could this be an advantage in that it 
would let us stretch the stuff out to our desired size?

>>>>Adam Beslove    (c)1985     (aka Odious Verity)
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(CSNet: beslove@ohio-state)		        The world is my sandbox,
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