Thanks, RMithe! I have always been in favor of bent pipe architectures, because the more processing and crosslinks you put in the space segment the more potential problems you are buying, not to mention the extra weight you are carrying into orbit. For that reason I have never been much of a Teledesic fan.
20Mbps is a lot in broadcast mode, but as I'm sure you know by the time you take into account the number of interactive users, their average download, etc, this bandwidth gets eaten up pretty quickly. I assume the uplink would be through terrestrial lines?
Are you familiar with the SkyCache architecture? Same idea (although I think they are using GEOs), but instead of broadcasting straight to the home, they use the satellites to refresh cache at local ISPs.
Also, while on the subject of satellites, will the Skybridge constellation be circular? Some time back I heard about the Ellipso concept of (obviously) elliptical LEOs (more like a few thousand kilometers rather than true LEO), the idea being that it is more efficient to hang over the populated areas as much as possible, although at higher altitude, and swing quickly around the southern hemisphere. There are other problems, though, such as having to traverse the radiation belts. Well, I'm rambling now... good to have another space guy on board :-) |
