Warner Losh imp at bsdimp.com
Tue Jan 17 14:36:28 EST 2012

Keep in mind that my prognostication was a "what would happen if" sort of thing. The people identified would need to change. They all fall into the 'care which way the earth is pointing' category. They are a tiny fraction of a fraction of 1% and would need to reengineer their operations if this change were to happen. My guess as to what would happen is just that, a guess. It shouldn't be taken as an engineering statement "since I don't think much bad will happen, this will be OK" but rather "if this were to happen, these folks must change."


On Jan 17, 2012, at 11:27 AM, Rob Seaman wrote:

> Steve Allen wrote:


>> Warner Losh hath writ:

>>> [*] Unless I'm an astronomer or care which way the earth is pointing to sub-minute accuracy.


>> The GPS system, and the other GNSS, must know that in order to operate.

>> The satellite tracking code, the VLBI code, the LLR code have all been

>> written and operated in the presence of leap seconds. The absence of

>> leap seconds could compromise the infrastructure that supports GPS.


> See Stephen Malys's* presentation and paper:

> - http://www.cacr.caltech.edu/futureofutc/program/presentations/AAS_11-675_Malys.pptx.pdf

> - http://www.cacr.caltech.edu/futureofutc/preprints/32_AAS_11-675_Malys.pdf


> From his summary slide:


> • DoD GPS Monitor Stations, the ‘starting point’ for all GPS Positioning, Navigation and Timing (PNT) are located on the Rotating Earth


> • A regular source of UT1-UTC predictions will continue to be needed for NGA, GPS and other DoD Satellite Operations


> • Allowing UT1-UTC to grow beyond the current 1 sec limit

> • Will require resources to modify existing ICDs and operational software

> • Offers no benefits to NGA or GPS Operations


> Rob


> * Senior Scientist for Geodesy and Geophysics, InnoVision Basic and Applied Research Office, National Geospatial- Intelligence Agency

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