On Mon 2007-01-15T08:53:19 -0700, Rob Seaman hath writ: > Any comments on the practicality of space-rating such timepieces?
GPS uses rubidium cells, and Galileo will. I've seen ruminations about flying a cesium resonator and an ion trap on ISS with a goal of redefining the SI second by allowing a long term calibration of the "continually probe-able on earth" ion against the "it always falls down on earth" cesium. > Also - what are the actual use cases requiring a common time scale, > rather than establishing a separate Martian civil cesium standard and > simply tracking the deltas? Robert A. Nelson. Look up his numerous presentations on a Mars version of GPS in CGSIC, PTTI, etc., and more recently IAU in Prague http://tycho.usno.navy.mil/IAU31/nelson.ppt (Which, by the way, includes the calculation that deviation between Mars coordinate time and Earth coordinate time is about 25 ms peak to peak.) -- Steve Allen <[EMAIL PROTECTED]> WGS-84 (GPS) UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99858 University of California Voice: +1 831 459 3046 Lng -122.06014 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
