On 7/9/16 1:40 PM, Joe Fitzgerald wrote:
On 7/9/2016 3:00 PM, jimlux wrote:
TAI my friend, TAI...
Hmm, gravitational time dilation it might complicate things ... I
suppose it depends on whether your Mars clock is on the surface of Mars,
Earth or somewhere else.
On 7/9/2016 3:34 PM, Hal Murray wrote:
How good is the data on the rotation rate for Mars? Is it good enough so
that they would need leap seconds?
Without an ocean or significant atmosphere I bet the rotation rate would
be more predictable than Earth - once good measurements were made. The
dearth of observatories on Mars suggests the current error bars on
current rate estimates pretty wide.
I'd guess the rate estimate is quite good. Wikipedia says
88,775.24409 seconds/sol
We can do very good ranging to MER and MSL. Phoenix didn't carry a
direct to earth transponder.
We can also do ranging from rovers to MRO, and then from MRO to Earth.
I don't know how much ranging we've done at UHF, though. The radio
wasn't really designed for it, so the math gets a bit complex, and I'm
not sure you can back out all the higher order terms. The UHF radio on
MRO does have a USO driving it, so it's timing performance should be
quite good in "open loop record" mode.
The uncertainty in the MRO range & range rate is probably less than for
the rovers, because the SNR is much better (big multi-meter antenna on
MRO helps a lot).
Fun to think about that's for sure.
-Joe
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