[tz] Sol 5000 for Opportunity

Marshall Eubanks marshall.eubanks at gmail.com
Sun Feb 18 14:54:56 UTC 2018

On Sun, Feb 18, 2018 at 2:27 AM, Steve Allen <sla at ucolick.org> wrote:

> On Sun 2018-02-18T00:08:25-0700 Brian Inglis hath writ:
> > Pretty presumptuous of the IAU to use Universal: they /should/ know
> better.
> Alas, Universal Time of 1928 is a subdivision of the already approved
> Universal Day, and that derives from the Victorian-era knowledge of
> astronomy and speech patterns of the 1884 International Meridian
> Conference.  Of regrettable things left over from time-keeping
> history, that is not the worst, and the Germans did explicitly avoid
> it by choosing Weltzeit as their term.
> If Mars denizens decide to choose a single legal time scale that is
> constructed from an amalgam of precision time and planetary rotation
> then it will also need leaps of some sort.  Hopefully they will avoid
> the attempt to bend a pre-existing time distribution system into doing
> two different time scales, and simply distribute their calendar days
> as one of several polynomial offsets from their underlying precision
> time and frequency distribution system.

Only if it drifts. Our planet's  UT1 drifts with respect to atomic time not
because of measurement errors, but because of internal exchanges of angular
predominately due to fluid motions in the liquid outer core. Mars has a
fluid outer core; whether or not it actually undergoes
significant long period drifts in planetary spin rate remains to be seen.
Hopefully, this will be answered by the
Insight lander set to go to Mars at the next launch window.

(Note - Like Viking and Pathfinder, Insight will not have a DSAC, but will
use round trip range and Doppler to measure Mars rotation rate with respect
to terrestrial Atomic Time.)


> --
> Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
> UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat
> +36.99855
> 1156 High Street               Voice: +1 831 459 3046         Lng
> -122.06015
> Santa Cruz, CA 95064           http://www.ucolick.org/~sla/   Hgt +250 m
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