North American Air Defence Command
Found on C.S.Y2K, from Cory Hamasaki
John
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'I found this in rec.radio.amateur.space
Note the YY format in the NORAD two line element set.
The two line element set is the standard definition of a satellite
orbit and is used by all commercial, military, and amateur orbital
simulators.
There are hundreds of millions, billions (US billions) of dollars of
software distributed in the hundreds of thousands of computers that
track the satellites and control the pointing of antennas for
communications, voice, digital, images, etc.
NORAD, the North American Air Defence Command, based in the hollowed out Cheyenne Mountain, shown in the movie "War Games", tracks the satellites and issues the two line element sets. When these element sets fail, lots of very high tech communications will also fail.
The element sets describe the position and vector of the satellite at
a specific starting time. The orbital simulator uses Newtonian
mechanics to predict the future (or past) position of the satellite,
this is called "Flying the bird" <not to be mistaken with 'giving the
bird', which Frank seems to be fond of giving me.> or "propagating
the orbit".
Again, like all these Y2K issues, this ain't a big deal. Simply
change the definition of the standard NORAD two card element set to
include the century or implement windowing in all the hundreds of
thousands of orbital simulators all over the world. Oh, no one knows
where they are? Oh, there are databases of these things with the YY and DD and the fractional day as keyed fields? Too bad for the high tech world.
Here's another thrill ride. Analytic Graphics Corporation pressed
and gave out 75,000 freeware copies of their $10,000 Satellite Tool
Kit. Every one of these copies is not Y2K compliant and they're all
over the world, some are doing critical work.
Oh, and the seed year and day isn't just for the report and -28 year
windowing won't work. The orbital simulators take into account the
absolute time and the effect that the Moon's gravitation has on
perturbating the satellite's orbit.'
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