Hi You might be surprised by how well the CSAC does in orbit. There have been a lot of cases over the years where a device has done much better once it is away from “poking fingers” like pressure and other semi-random stuff ….
Bob > On Dec 8, 2018, at 1:49 PM, jimlux <[email protected]> wrote: > > On 12/8/18 10:12 AM, Peter Monta wrote: >> If a little eccentricity makes for a good test of relativity, wouldn't a >> lot of eccentricity be even better? :-) >> Does anyone know what clock facilities are on the Parker solar probe? >> Atomic clock? And a drag-free mode would have been great too, but I doubt >> that was included. > > Extremely unlikely.. I know one of the PIs for Parker, I'll ask him. > If anything, they would fly a USO (a really good crystal in a temperature > stabilized enclosure). > > I'm flying an atomic clock (a CSAC), launching next week, but it will be in a > circular orbit, and I'll bet the gravity variations are small enough that > they are less than the uncertainty. > > The other problem is that you need to *measure* that atomic clock against > something. The best I can do with my CSAC is compare its 1pps against a > Novatel OEM-6 single frequency GPS 1pps, and an onboard 100 MHz oscillator - > none of them are outstanding by timenuts standards. > > (CSAC is around 1E-12 at 1000-10000 seconds - see > http://www.leapsecond.com/pages/csac/ > > It's about an order of magnitude worse than a PRS-10 Rb) > > Tom, with his herd of clocks, can leave some at home and take some with him, > and compare them upon return. > > I would imagine that someone looks at the behavior of the atomic clocks on > the GPS satellites in excruciating detail. The signals from GPS are > incredibly well studied, and have been recorded at carefully maintained > ground sites for decades with high quality reference clocks. > > > There are folks developing and flying a Deep Space Atomic Clock (DSAC), a > trapped Hg-ion, which is substantially better. Launch is currently March > 2019 (on the Falcon Heavy) It's a bit of a beast: 17.5kg, 17.4 liters (a bit > bigger than their original goal of 1kg, 1 liter, <grin>) and 44 watts. > > It's supposedly going to be in the 1E-14 range at 1000 seconds, and 1E-15 at > 100,000 seconds. > > It will be in LEO, but maybe you can see the variation from the Moon and Sun? > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
