http://www.outfittersatellite.com/blog/iridium-next/whats-ir...
Which one to buy !
- Arizona - Hawaii (Military only) - Russia
and then it is routed through the fibre backbone.
With the SpaceX proposal there will be more ground egress points, so it will be able to get closer to the destination before grounding.
SpaceX's 2 test satellites were 400 kg.
The concept 'Size, Weight, and Power' (SWaP) is commonly used when comparing FSO vs. RF systems. Incidentally, FSO systems have lower SWaP than RF systems. They're smaller and lighter payloads, and the system requires less poweR.
Hopefully the telecoms market has changed enough since then (cf Iridium's recent profitability, even while launching a whole new constellation) to make it suddenly viable.
SpaceX's network seems to work the other way around by being designed around fast-moving satellites and complex ground terminals that do the tracking and hand-overs by means of phase array antennas (ie. completely solid-state). In comparison to Inmarsat it is not GEO-bounce and in comparison to Iridium they seem to have some solution for having fully connected mesh of satellites (original Iridium is not fully connected sphere as there isn't even attempt to have link between satellites with oposite orbits)
In fact, the SpaceX proposal looks a lot like the Iridium concept in general, but with thousands of little satellites instead of dozens of larger ones (which probably makes the implementation very different).