[time-nuts] GPS disciplined Mars clock
Bob Camp
kb8tq at n1k.org
Sat Jul 9 23:56:11 UTC 2016
Hi
Obviously time for a Kickstarter campaign to put a set of observatories on Mars ….
Bob
> On Jul 9, 2016, at 5:59 PM, jimlux <jimlux at earthlink.net> wrote:
>
> 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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