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Shuttle computers can't count :-P

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  • Shuttle computers can't count :-P



    Shuttle Computers Find No End to 2006

    Posted on November 7, 2006 @ 02:36:25 EST
    Author Tariq Malik

    One year might as well be an eternity for NASA’s space shuttles, which – it turns out – have no automatic reset once the calendar hits Jan. 1, 2007.

    “The interesting thing about the shuttle computers and the ground computers that support the shuttle is that they were never envisioned to fly through a year-end changeover,” says NASA’s shuttle chief Wayne Hale here at the agency’s Johnson Space Center. “So the shuttle computers actually keep counting and they believe that it is Day 366 instead of Day 1 of the New Year.”
    More....

    NASA hopes to get its next space shuttle off the launch pad and back on the ground by the end of 2006 in order to avoid computer problems similar to those once ascribed to 'Y2K'. It is now considering moving the shuttle Discovery's planned lift-off ahead by one day, to 6 December.

    The space shuttle's computer software is about 30 years old and does not recognise when the calendar year switches. On 1 January 2007, for example, it will think it is day 366 of 2006 – a problem NASA calls 'year-end rollover'.

    To reset the time, the shuttle's main computers would have to be 'reinitialised', which would mean a period without navigation updates or vehicle control, a situation NASA obviously wants to avoid.

    NASA had already moved the shuttle's target launch date from 14 to 7 December – in part to avert the year-end issue and in part to allow shuttle workers to rest over the holidays. Now, it is considering moving lift-off one day earlier, to 6 December, to give launch teams another chance to get the shuttle off the ground before the new year.
    Last edited by Dr Mordrid; 7 November 2006, 23:54.
    Dr. Mordrid
    ----------------------------
    An elephant is a mouse built to government specifications.

    I carry a gun because I can't throw a rock 1,250 fps

  • #2
    I don't understand why the computer would even keep track of the date like that? I'd think they'd use an abritrary starting point as day "zero" (like when the computer is first booted up on the pad or something similar) and count upwards from there, or use the Julian day which is more useful for astronomical calculations than the conventional date.

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    • #3
      Got me. Anything's better than what it does now
      Dr. Mordrid
      ----------------------------
      An elephant is a mouse built to government specifications.

      I carry a gun because I can't throw a rock 1,250 fps

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      • #4
        Aww, don't quote only basic desription of what's happening - it sounds absolutelly trivial ("ok, so the computers will count, say, 370 days in a year...so?") untill reading the links, and on this machine (128mb of ram) this isn't trivial

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        • #5
          What does the amount of memory a system have have to do with a date roll-over problem? The shuttle main computers only have 1000 kilobytes of non-volatile memory which is used both to hold the software and act as RAM.

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          • #6
            Well, if you count far enough you need more memory to keep track, y'a know, smallint, int, hugeint, 1MB of ram ints etc.
            Join MURCs Distributed Computing effort for Rosetta@Home and help fight Alzheimers, Cancer, Mad Cow disease and rising oil prices.
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            • #7
              The amount of memory in a system is what led to the Y2K bug.

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