Re: 2-line elements in Year 2000.

JAY RESPLER (jrespler@InJersey.com)
Sun, 14 Sep 1997 22:41:41 -0400 (EDT)

> The Elements' Date (year) epoch is only 2-digits at present; (starting in
> 1957 I presume). Also needs to be changed to 4-digits. Some software will
> get confused with year '99' (1999) Keps, and using them to try to work out
> year '00' (2000) pass predictions. Also there will be a repeat in the year
> 2057 for any object that was launched in 1957 and that is still in orbit.

Sorry, but is someone suggesting how to change elements without knowing 
that there is nothing launched in 57 that is still in orbit?

> Orbit numbers are now wrapping around on some early high-rev objects. Need
> another two (maybe 3) digits at least, to allow for a 15 Revs per day object
> staying in space for 500 years.

Anything with MM of 15 will not stay in orbit for 500 years. 
Personally, I'll worry about how to handle elements 500 years from now as 
the date gets closer    :)


> There needs to be a proper system for issuing pre-launch Keplers. Proper
> numbering. Proper object Identification. Or an agreement that the Object

It is impossible to have 'proper number or object Id' before launch.
By definition, they are only assigned after launch.

> I don't like '.TLE' because I find that a lot of people call '.TLE' files
> 'TELEMETRY FILES' when they are actually talking about NASA / NORAD 2-line
> Kepler Elements Files.

I have never heard this. From probably the first time I saw TLEs, I read 
that they stood for Two Line Elements.  I don't see how anyone can use 
TLEs for any time without knowing what they are. Knowing that, why would 
they call them something else?


> Present NORAD 2-line Kepler Element Data Format: > 
>    Mir
>    1 16609U 86017A   96276.19408002  .00000915  00000-0  16289-4 0  6923
>    2 16609  51.6519 304.8165 0012480 224.8931 251.6678 15.62085522606724
> 
> Proposed 3-line Kepler Element Data Format (3 lines of 64 characters):
>    Mir
>    1 0016609U 000692 19860017A   1996276.1940800200  +.0000091500 9
>    2 0016609  000692 051.6519 304.8165 .0012480 224.8931 251.6678 9
>    3 0016609  000692 15.6208552200 00060672 +.00000-0 +.16289-4 0 9
>    4 0016609  000692 Orbit boost due 1996-10-08 approx.

Doesn't the present format look much simpler than the proposed one?

Currently elements are over 1 meg in size. Is it realized that this could 
double that? Is that desirable?


Jay Respler
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              JRespler@InJersey.com  
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