Mars -> Earth time

It's been reported in many places that the MER teams
are operating on "Mars time"..i.e., days that are
~24 hrs. and 39 minutes long.

Does anyone know the details of how the discrepancy is
made up? I.E., do the clocks that the teams look at display?
Did they create a 25th "hour" in the day that's only ~39
minutes long? Did they keep a 24-hour clock, but make the hour
longer? And if the latter, did they add extra minutes to
each hour, add extra seconds to each minute, make the
second longer, or what?

It seems unlikely that they would want to tamper with the
second, minute, or hour, as those are all units that can
be used in basic engineering caculations. Altering those
could cause problems.

On Thu, 15 Jan 2004 17:08:34 +0000 (UTC), Epawtows
wrote:

It's been reported in many places that the MER teams
are operating on "Mars time"..i.e., days that are
~24 hrs. and 39 minutes long.

Does anyone know the details of how the discrepancy is
made up?

Whether to divide the Mars day like Earths (with each time period just
a hair longer) or to add extra minutes onto the end of the day is a
tricky question that has been debated in various settings over time with
no clear winner. My inclination is that retaining the second as a fixed
increment makes the most sense, with engineering calculations carried
out, Un*x style, with everything converted to standard seconds.

http://marsrovers.jpl.nasa.gov/spotl..._20040108.html
implies that the "Mars watches" are using slowed time, as it talks about
adding weights, not changing gear tooth counts. This makes a certain
amount of sense when you are concerned with Mars solar time for a
solar-powered rover. These, however, are mostly being used for purposes
where second by second accuracy is not critical. I don't know whether
this approach carries over to engineering calculations, hopefully some
other poster with more detailed information will answer.

** James **

Epawtows wrote:

It's been reported in many places that the MER teams
are operating on "Mars time"..i.e., days that are
~24 hrs. and 39 minutes long.

Does anyone know the details of how the discrepancy is
made up? I.E., do the clocks that the teams look at display?
Did they create a 25th "hour" in the day that's only ~39
minutes long? Did they keep a 24-hour clock, but make the hour
longer? And if the latter, did they add extra minutes to
each hour, add extra seconds to each minute, make the
second longer, or what?

AIUI, the clocks simply go to 24:39 or so, then wrap round.
Altering the second just gets messy, and there is no way to do it
cleanly changing the number of minutes or seconds without abominations
like "leap seconds".