From efbae189bc3eb2b7c1efbe79ed6e2ab7b22cae24 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Tue, 30 Jun 2020 16:39:43 -0700 Subject: [PROPOSED] Cite Mirmalek on Martian timekeeping MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * theory.html (Time and time zones on other planets): Update discussion of Martian timekeeping and cite Mirmalek 2020. (Thanks to Michelle Bastian for a pointer to Mirmalek’s earlier work.) --- theory.html | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/theory.html b/theory.html index 1a5b568..22b9815 100644 --- a/theory.html +++ b/theory.html @@ -1327,17 +1327,21 @@ They sometimes disagree.

Time and time zones on other planets

-Some people's work schedules -use Mars time. +Some people's work schedules have used +Mars time. Jet Propulsion Laboratory (JPL) coordinators kept Mars time on and off during the Mars -Pathfinder mission. +Pathfinder mission (1997). Some of their family members also adapted to Mars time. Dozens of special Mars watches were built for JPL workers who kept -Mars time during the Mars Exploration Rovers mission (2004). -These timepieces look like normal Seikos and Citizens but use Mars -seconds rather than terrestrial seconds. +Mars time during the +Mars +Exploration Rovers (MER) mission (2004–2018). +These timepieces looked like normal Seikos and Citizens but were adjusted +to use Mars seconds rather than terrestrial seconds, although +unfortunately the adjusted watches were unreliable and appear to have +had only limited use.

@@ -1345,6 +1349,8 @@ A Mars solar day is called a "sol" and has a mean period equal to about 24 hours 39 minutes 35.244 seconds in terrestrial time. It is divided into a conventional 24-hour clock, so each Mars second equals about 1.02749125 terrestrial seconds. +(One MER worker noted, "If I am working Mars hours, and Mars hours are +2.5% more than Earth hours, shouldn't I get an extra 2.5% pay raise?")

@@ -1360,12 +1366,12 @@ called Mars Coordinated Time (MTC).

Each landed mission on Mars has adopted a different reference for solar timekeeping, so there is no real standard for Mars time zones. -For example, the -Mars -Exploration Rover project (2004) defined two time zones "Local +For example, the MER mission defined two time zones "Local Solar Time A" and "Local Solar Time B" for its two missions, each zone designed so that its time equals local true solar time at approximately the middle of the nominal mission. +The A and B zones differ enough so that an MER worker assigned to +the A zone might suffer "Mars lag" when switching to work in the B zone. Such a "time zone" is not particularly suited for any application other than the mission itself.

@@ -1414,7 +1420,12 @@ Sources for time on other planets: Michael Allison and Robert Schmunk, "Technical Notes on Mars Solar Time as Adopted by the Mars24 Sunclock" - (2018-12-13). + (2020-03-08). + +
  • + Zara Mirmalek, + Making + Time on Mars, MIT Press (March 2020), ISBN 978-0262043854.
  • Jia-Rui Chong, -- 2.17.1