I think radiation damage and solar wind are going to be bigger problems than orbital tension. Brent On 7/27/2015 12:46 PM, Henry Baker wrote:
I suppose that one could put the entire 265,000km fiber reel into geosynchronous orbit, and then allow a smaller satellite to slowly unreel the cable as it finds its geostationary location exactly as it's done now. (Think about a fly fishing reel.)
I haven't done the calculation, but I was hoping that the forces on the cable would be sufficiently small to allow the cable itself to do the "station keeping", so that far less expendable fuel would be required.
Once the cable is installed, it would probably be a good idea to keep all of the satellites properly positioned with *only* forces perpendicular to the cable itself. Alternatively, if the entire ring needs to be shifted or modified, then any firings would have to be synchronized; synchronization should be easy to arrange using the *communications* capability of the cable itself.
Of course, communications among the satellites could also be arranged using lasers, and lasers have a 1.5x (or more, so long as they don't have to pass through the Earth) speed advantage. However, it isn't clear that lasers wouldn't require more complexity and more power to achieve the same communications bandwidth.
At 12:27 PM 7/27/2015, Andy Latto wrote:
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. Andy.Latto@pobox.com
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