Re: Routers... in Space!
" Interplanetary comms relies on a massive dish/array at one end (for ease of logistics, we tend to keep that one on earth), and a small dish at the other "
To elaborate, the distance to Neptune (Pluto's orbit is irregular) is about 30AU. A dish near Jupiter (5AU) would spend roughly half of its time on the wrong side of its orbit and would actually be further away than Earth, so let's assume you have several. Even at its closest point, it is still 25AU from Neptune and to be worth doing, the dishes around Jupiter would need to be at least 5/6 of the diameter of the one on Earth. (They need to subtend the same solid angle.) Then they have to re-transmit the message back, but that's a much easier problem because the transmitter can be only 1/36 of the power of the one near Neptune and still deliver the same signal strength to Earth.
Move the intermediate to Saturn, at 10AU, and you need only 2/3 of the diameter of a dish on Earth, but you've got to get all the dishes out as far as Saturn *and* the retransmission needs to be four times more powerful.
It would appear that the economics are overwhelmingly weighted in favour of a single hop to a bloody enormous dish on Earth, where construction costs are essentially free (by comparison), power consumption (for transmission back to the craft) is no object, and there's always the options of technological upgrades and repairs whilst the mission is in progress.
Biting the hand that feeds IT
