90 lines
3.7 KiB
Diff
90 lines
3.7 KiB
Diff
From efbae189bc3eb2b7c1efbe79ed6e2ab7b22cae24 Mon Sep 17 00:00:00 2001
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From: Paul Eggert <eggert@cs.ucla.edu>
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Date: Tue, 30 Jun 2020 16:39:43 -0700
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Subject: [PATCH 18/47] Cite Mirmalek on Martian timekeeping
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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* theory.html (Time and time zones on other planets):
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Update discussion of Martian timekeeping and cite Mirmalek 2020.
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(Thanks to Michelle Bastian for a pointer to Mirmalek’s earlier work.)
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---
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theory.html | 31 +++++++++++++++++++++----------
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1 file changed, 21 insertions(+), 10 deletions(-)
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diff --git a/theory.html b/theory.html
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index 1a5b568..22b9815 100644
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--- a/theory.html
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+++ b/theory.html
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@@ -1327,17 +1327,21 @@ They sometimes disagree.
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<section>
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<h2 id="planets">Time and time zones on other planets</h2>
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<p>
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-Some people's work schedules
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-use <a href="https://en.wikipedia.org/wiki/Timekeeping_on_Mars">Mars time</a>.
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+Some people's work schedules have used
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+<a href="https://en.wikipedia.org/wiki/Timekeeping_on_Mars">Mars time</a>.
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Jet Propulsion Laboratory (JPL) coordinators kept Mars time on
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and off during the
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<a href="https://en.wikipedia.org/wiki/Mars_Pathfinder">Mars
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-Pathfinder</a> mission.
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+Pathfinder</a> mission (1997).
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Some of their family members also adapted to Mars time.
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Dozens of special Mars watches were built for JPL workers who kept
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-Mars time during the Mars Exploration Rovers mission (2004).
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-These timepieces look like normal Seikos and Citizens but use Mars
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-seconds rather than terrestrial seconds.
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+Mars time during the
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+<a href="https://en.wikipedia.org/wiki/Mars_Exploration_Rover">Mars
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+Exploration Rovers (MER)</a> mission (2004–2018).
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+These timepieces looked like normal Seikos and Citizens but were adjusted
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+to use Mars seconds rather than terrestrial seconds, although
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+unfortunately the adjusted watches were unreliable and appear to have
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+had only limited use.
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</p>
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<p>
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@@ -1345,6 +1349,8 @@ A Mars solar day is called a "sol" and has a mean period equal to
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about 24 hours 39 minutes 35.244 seconds in terrestrial time.
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It is divided into a conventional 24-hour clock, so each Mars second
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equals about 1.02749125 terrestrial seconds.
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+(One MER worker noted, "If I am working Mars hours, and Mars hours are
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+2.5% more than Earth hours, shouldn't I get an extra 2.5% pay raise?")
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</p>
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<p>
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@@ -1360,12 +1366,12 @@ called Mars Coordinated Time (<abbr>MTC</abbr>).
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<p>
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Each landed mission on Mars has adopted a different reference for
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solar timekeeping, so there is no real standard for Mars time zones.
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-For example, the
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-<a href="https://en.wikipedia.org/wiki/Mars_Exploration_Rover">Mars
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-Exploration Rover</a> project (2004) defined two time zones "Local
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+For example, the MER mission defined two time zones "Local
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Solar Time A" and "Local Solar Time B" for its two missions, each zone
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designed so that its time equals local true solar time at
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approximately the middle of the nominal mission.
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+The A and B zones differ enough so that an MER worker assigned to
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+the A zone might suffer "Mars lag" when switching to work in the B zone.
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Such a "time zone" is not particularly suited for any application
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other than the mission itself.
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</p>
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@@ -1414,7 +1420,12 @@ Sources for time on other planets:
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Michael Allison and Robert Schmunk,
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"<a href="https://www.giss.nasa.gov/tools/mars24/help/notes.html">Technical
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Notes on Mars Solar Time as Adopted by the Mars24 Sunclock</a>"
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- (2018-12-13).
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+ (2020-03-08).
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+ </li>
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+ <li>
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+ Zara Mirmalek,
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+ <em><a href="https://mitpress.mit.edu/books/making-time-mars">Making
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+ Time on Mars</a></em>, MIT Press (March 2020), ISBN 978-0262043854.
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</li>
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<li>
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Jia-Rui Chong,
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--
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1.8.3.1
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