[math-fun] geostationary glass fiber ring
Does these calculations make sense? glass has density of 2.5 g/cm^3 typical single mode fiber core diameter 8.3 micrometers. geosynchronous orbit: 42,164km radius; 265,000km circumference. volume of glass for geosynchronous fiber: pi*(8.3µm/2)^2*265000km = 0.014334011188882 m^3 (?) density of glass = 2500kg/m^3 Mass of geosynchronous glass = 36 kg (?) I'm quite sure that today's geosynchronous satellites weigh more than 80 pounds! (Yes, I know, this is only for the core of the fiber; a geosynchronous fiber would also require cladding, but one might optimize the cladding for this particular application if one were to really pursue this technology.) So a geosynchronous optical fiber ring is eminently doable with today's technology! Such a ring could conceivably transmit 1 Tbit/second at ~2/3 c (= 200,000km/s) This ring would hold 1.3 seconds of data = 1.3 Tbits = 162 GBytes.
On 2015-07-27 09:57, Henry Baker wrote:
Does these calculations make sense?
glass has density of 2.5 g/cm^3
typical single mode fiber core diameter 8.3 micrometers.
geosynchronous orbit: 42,164km radius; 265,000km circumference.
volume of glass for geosynchronous fiber: pi*(8.3µm/2)^2*265000km = 0.014334011188882 m^3 (?)
density of glass = 2500kg/m^3
Mass of geosynchronous glass = 36 kg (?)
I'm quite sure that today's geosynchronous satellites weigh more than 80 pounds!
(Yes, I know, this is only for the core of the fiber; a geosynchronous fiber would also require cladding, but one might optimize the cladding for this particular application if one were to really pursue this technology.)
So a geosynchronous optical fiber ring is eminently doable with today's technology!
Such a ring could conceivably transmit 1 Tbit/second at ~2/3 c (= 200,000km/s)
This ring would hold 1.3 seconds of data = 1.3 Tbits = 162 GBytes.
Yeah, threads don't weigh much. I once computed that a molecule of polyethylene spanning the observable Universe would fit in Hangar 1. http://www.nasa.gov/centers/ames/home/2008/hangar_index.html --rwg
How would you deploy the ring? Suppose you have the fiber on a reel in a geosynchronous satellite. How would you unreel it to make the ring? Another computation worth doing is how accurate the placement of the ring would be, so that tension forces in the ring don't break it. Andy On Mon, Jul 27, 2015 at 12:57 PM, Henry Baker <hbaker1@pipeline.com> wrote:
Does these calculations make sense?
glass has density of 2.5 g/cm^3
typical single mode fiber core diameter 8.3 micrometers.
geosynchronous orbit: 42,164km radius; 265,000km circumference.
volume of glass for geosynchronous fiber: pi*(8.3µm/2)^2*265000km = 0.014334011188882 m^3 (?)
density of glass = 2500kg/m^3
Mass of geosynchronous glass = 36 kg (?)
I'm quite sure that today's geosynchronous satellites weigh more than 80 pounds!
(Yes, I know, this is only for the core of the fiber; a geosynchronous fiber would also require cladding, but one might optimize the cladding for this particular application if one were to really pursue this technology.)
So a geosynchronous optical fiber ring is eminently doable with today's technology!
Such a ring could conceivably transmit 1 Tbit/second at ~2/3 c (= 200,000km/s)
This ring would hold 1.3 seconds of data = 1.3 Tbits = 162 GBytes.
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rwg