On Fri 2007-01-12T18:35:55 +0000, Tony Finch hath writ: > According to the slides linked from Dave Mills's "Timekeeping in the > Interplanetary Internet" page, they are planning to sync Mars time to UTC. > http://www.eecis.udel.edu/~mills/ipin.html
Neverminding the variations on Mars with its rather more eccentric orbit, the deviations from uniformity of rate of time on earth alone create an annual variation of almost 2 ms between TT and TDB. This is also ignoring variations in time signal propagation through the solar wind when Mars is near superior conjunction. To some applications 2 ms in a year is nothing. From an engineering standpoint a variation of 2 ms in a year on Mars is certainly better than any time scale that could be established there in lieu of landing a cesium chronometer. To other applications 2 ms in a year may be intolerably large. So the question remains: At what level do distributed systems need access to a time scale which is uniform in their reference frame? And my question: Can something as naive as POSIX time_t really serve all such applications, even the ones on earth, for the next 600 years? -- 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
