Re: Why is that accuracy necessary?
"you bounce a signal off it from the DSN on Earth and measure, on Earth, how long that took using a really good clock"
An extension of the problem is you don't always know with exact certainty how long the "bounce" process took (i.e. the time taken for the onboard computer to receive the ping, process it, trigger a transmission back). Even if you know with certainty how many cpu cycles that took, you're timing is based on the clock frequency of the onboard cpu, which isn't accurate enough either.
Biting the hand that feeds IT
