Re: [LEAPSECS] Comments on Civil Time decision tree

From: Randy Kaelber <>
Date: Mon, 26 Sep 2005 15:47:49 -0700

On Mon, Sep 26, 2005 at 10:35:15PM +0200, Poul-Henning Kamp wrote:
> In message <>, I wrote:

> >That's the way we do it for interplanetary stuff now. Data from
> >spacecraft are typically returned in spacecraft clock time (SCLK, which is
> >pronounced "sclock") and then translated to whatever time base you want it
> >in. Right now, the clock on Mars Odyssey (as I type this) should be
> >reading 2/0812228033. Dealing with things like leap seconds, local time
> >conventions, and other time conversions are all handled here on Earth.
> But that strategy breaks down for human space flight ?

I don't really see why it would. Humans on Mars would probably hold to a
Martian solar day to do work much in the same way the mission ops did with
the rovers. The science data would likely all still be mapped to a clock
associated with the spacecraft. Most manned Mars mission plans I've seen
involve multiple spacecraft (landers, orbiters, rovers) and I imagine each
would have its own onboard clock. Some of those would involve
coordination, I'm sure, but we do coordinated observations between
different missions all the time anyway, and I believe that experience
directly translates. When all is said and done, resolving small time
differences ranks relatively low on the list of challenges of
interplanetary manned space flight.

As an aside, most of the people who were/are on Mars Rover teams that I
talked to really liked the extra 30+ minutes a day. The only thing they
didn't like was when mundane earthbound things conflicted (It's 4 am, but
I don't want to eat at Denny's and I really need to get to the bank.) with
their Martian schedule. Astronauts on Mars would not have that problem.

Randy Kaelber                              
Scientific Software Engineer
Mars Space Flight Facility, Department of Geological Sciences
Arizona State University, Tempe, Arizona, USA
Received on Mon Sep 26 2005 - 15:48:45 PDT

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