It occurs to me that the signal from these old spacecraft beyond the orbit of Pluto are very faint and often buried in the quantum noise. The spacecraft get their signal to Earth by constantly repeating themselves. The same signal is received again-and-again until enough of it is integrated to rise above the background noise. This is unlike Cassini or MER where the DSN can get a complete signal on the first pop. If cost is based upon an hourly basis then these old spacecraft are expensive to listen to. However the assumption of charging on an hourly basis is nonsense. The DSN exists to service funded spacecraft like Cassini and MER. The DSN only uses its resources on old spacecraft when it is between performing its funded tasks. This is "full cost accounting" gone haywire.

Gary