[LEAPSECS] The leap second, deep space and how we keep time -Brooks

[Matsakis, Demetrios]

The marketplace.org article quotes Bob Tjoelker as saying his team, and deep-space missions in general, can handle leap seconds.   I've known Bob Tjoelker for years.   He's a super-scientist designing super-clocks.  Since some of those clocks are space-qualified, he is literally a rocket scientist.   But it should also be noted that the marketplace.org article did not point out that most of us are not at his level.   Also, they chose not to quote him about concerns he expressed about other systems.

As an example, last week some GPS receivers (of different models) apparently implemented the coming leap second as soon as GPS  began broadcasting its leapsecond-pending flag.  While their jumps could have been due to something else, and the receivers did not jump with the last leap second, the coincidence raises strong suspicions that the receivers were misprogrammed.    This failure was discovered because the receivers' associated NTP servers gave out the wrong time.  For reference see http://lists.ntp.org/pipermail/pool/2015-January/007272.html.

Equally unfortunate is that 30 servers in the NTP pool inserted a leap second last Dec 31.  Even if a DNS-based reference helps with some of these issues, there would remain a host of other opportunities for failure, such as systems mis-programmed so they insert leap seconds after 23:59:59 local time instead of UTC.

As always these are my personal opinions, and not those of my employer or the US Government.   In that sense I note that NASA is very good at proactively preventing mistakes, and I suspect this consideration contributed to its anti-leapsecond position, which itself contributed the American government's decision to support the proposal calling for the elimination of future leap seconds after the suitable waiting period.

-----Original Message-----
From: LEAPSECS [mailto:leapsecs-bounces at leapsecond.com] On Behalf Of Brooks Harris
Sent: Sunday, January 25, 2015 11:35 AM
To: Leap Second Discussion List
Subject: [LEAPSECS] The leap second, deep space and how we keep time -Brooks

The leap second, deep space and how we keep time http://www.marketplace.org/topics/world/leap-second-deep-space-and-how-we-keep-time

Much less stupid than many popular reports...

-Brooks
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