[time-nuts] GPS disciplined Mars clock

jimlux jimlux at earthlink.net
Sat Jul 9 17:59:54 EDT 2016


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
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>




More information about the time-nuts mailing list