What time is it on the ISS?

Discussion in 'Physics' started by amilton542, Mar 14, 2014.

  1. amilton542

    Thread Starter Active Member

    Nov 13, 2010
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    I've been watching this documentary called "Live from Space", and it's primarily about living on the ISS (International Space Station) and I found it interesting when they started referring to what time it was back at home.

    But what time does it make it on the ISS?
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
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    they use gmt, or coordinated univeral time.
     
  3. WBahn

    Moderator

    Mar 31, 2012
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    This is a problem that ships at see face (only the ISS is a more extreme example). The answer is quite arbitrary but comes out of asking what is important about keeping track of "time" to begin with. That answer will differ for a cruise ship versus a long-cruise submarine. For something like the ISS, the only reasonable answer is a location-independent time reference such as GMT, Coordinated Universal Time, GPS time or something similar. The differences between these is well-defined and can be taken into account when and where it matters.
     
  4. #12

    Expert

    Nov 30, 2010
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    A less technical point of view...It's any time you want it to be, but it would be a healthy choice to use a 24 hour day in order to avoid confusing the diurnal cycle of a normal human.
     
  5. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    The ISS is quite different from vessels because even sailing with True course 090 / 270 (east / west bound) they would not cross a full time zone in less than one day.

    Ships keep the time corresponding to the time zone where they are in.

    As they cross, they change the time and if necessary, the date (jumping ahead or backwards) as well. By sheer coincidence, I had my birthday's repeated once (double celebration) and many years later, elegantly skipped. Tell me about keeping accounts even...

    Since the prevailing system is to keep the service on board organized in periods of 4 hours (mostly in the bridge and engine room if if it is not unattended) the 3 night watches, each one sets back / advances the time 20 minutes each. Log books reflect the change at the start of each period. Simple but good enough for disoriented people to wake up too soon or too late...

    Time ago, there was a site where to ask specific questions (not in FAQ lists) to NASA's staff. They took care to reply quite quickly.
     
    Last edited: Mar 18, 2014
  6. WBahn

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    Mar 31, 2012
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    Certainly the speed of the ISS makes using the "local" time zone completely impractical since it crosses a time zone in something on the order of six minutes or so.

    Vessels can cross time zones in less than a day in the higher latitudes, but it is still slow enough that it is reasonable, depending on context, to use local time.
     
  7. strantor

    AAC Fanatic!

    Oct 3, 2010
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    Careful there, bringing up submarines runs a high risk of elevating #12's blood pressure to an uhealthy level

    (Personal jab @ #12) ;)
     
  8. #12

    Expert

    Nov 30, 2010
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    I have no experience with submarines. I only assume they are cramped and smelly and spend most of their time wondering how to keep busy with no wars to fight. No reason to get my blood pressure up. :D
     
    strantor likes this.
  9. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    My experience in Antarctica (or for the case in Ushuaia) says that when the sun stays many hours (if not all the time) above (or below) the horizon, better you keep a time reference to follow. Otherwise you risk to get your habits (sleep basically) confused. :eek:

    Staying awake is not the biggest problem but working hard after few days of doing that, IS a problem. :(

    Not directly but somehow distantly related, the film "Insomnia" came to my mind. I enjoyed it twice.

    Have a good sleep!
     
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