sher@rochester.UUCP (David Sher) (05/27/85)
In response to the article on the possibility an ultra-light space probe moved by a light sail, has anyone considerred the possibility of building a lightsail out of photo-electric material? I know that thin film processes are already well advanced (as shown by the common light powered pocket calculator). I suspect that a light-sail can be made out of anything (except neutronium :-) as long as its thin. This would solve the problem of a power source for the probe, a few thousand square meters is probably sufficient power collection area for most purposes. It might just be possible to use the ion bombardment as a power source since that should cause a charge differential between a lighted and shaded object in space. The main problem would be grounding and the behavior of circuitry in highly charged environments. The max efficiency loss due to photoelectric effect on a light sail is 50%. Enuf thoughts, any comments? -David
chuck@dartvax.UUCP (Chuck Simmons) (05/29/85)
> In response to the article on the possibility an ultra-light space probe moved > by a light sail, has anyone considerred the possibility of building > a lightsail out of photo-electric material? I know that thin film > processes are already well advanced (as shown by the common light > powered pocket calculator). I suspect that a light-sail can be made > out of anything (except neutronium :-) as long as its thin. I imagine that aluminum has three big advantages: (1) aluminum atoms are very light; (2) aluminum is highly reflective; (3) it is relatively easy to make relatively thin (and therefore light) sheets of aluminum. One approach that interests me: would it be possible to "grow your own"? 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
beslove@osu-eddie.UUCP (Adam Beslove) (06/01/85)
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) ====================================================================== (UUCP: ...!cbosgd!osu-eddie!beslove) (CSNet: beslove@ohio-state) The world is my sandbox, (ARPA: beslove%ohio-state.csnet@CSNET-RELAY) humanity my playmates.
al@aurora.UUCP (Al Globus) (06/06/85)
> 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. > > I believe that Eric Drexler worked on very thin film solar sails while he was (is?) at MIT. I think he even fabricated some of the material, although 0g techniques would be required to make full sized sails.