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