[time-nuts] Re: Project Great

[Bernd Neubig]

-----Jim wrote-----

I wouldn't actually think there's a Cs on ISS.  What purpose would it serve?  We as time-nuts think "of course you'd have a precise source of time", but really, there's not much need for timing on ISS on a scale smaller than seconds, if that.  NTP to timestamp files, for instance.

You are probaly right about the actual situation. However there is the ESA ACES project idling since years without being launched yet:
"ACES is an ESA ultra-stable clock experiment, a time and frequency mission to be flown on the Columbus module of the ISS (International Space Station), in support of fundamental physics tests. The mission objectives are both scientific and technological and is of great interest to two main scientific communities:
• The Time and Frequency (T&F) community; which aims to use ACES as a tool for high precision Time and Frequency metrology
• The Fundamental Physics community; which will benefit from the use of ACES data for accurate tests of general relativity.

See https://earth.esa.int/web/eoportal/satellite-missions/i/iss-aces

The ACES development was initiated in the 1990s. However, the decision to complete the development of the project has been achieved only at the ESA council at Ministerial Level of November 2008.
The launch was planned in 2018, but,  as said, the clock ensemble (which BTW includes two AXTAL OCXO 100 MHz) is still sitting on the test bench and waiting and waiting.

Best regards
Bernd