[amsat-bb] drafting sputnik-1 tle
andy thomas
andythomasmail at yahoo.co.uk
Sun Sep 23 02:46:46 PDT 2007
Looking at my previous posting I can see that the RAE
data is different from the data on the SEESAT site as
I am trying to put it into tle format.
As suggested, it'll be great to run it as a simulation
using contemporary keps exactly 50 years old.
I remember some years ago writing a simple prediction
program using some of the TLE data and getting a print
out from NASA identifying the elements in the two line
set, and now I see it's reproduced on the amsat'org
website.
But I do not know how to calculate the RAAN, the Mean
Anomolay and the Checksum, and I make an assumption of
zero drag.
So far I have:
SPUTNIK-1
1 000001U 57 1 A 57277.8 .CCCCCCCC 000000-0
000000-0 0 Z
2 00000165.1000 III.IIII 052000 58.000 MMMM.MMMM
14.92723492 Z
The bits I don'tknow how to calculate are:
.CCCCCCCC this is the drag factor - can it just be
set to zero initially?
III.IIII this is the infamous RAAN - I gather it is
calulated from the Mean Motion and a reference time
but don't know any more
MMM.MMMM this is the Mean anomoly and again I wonder
if it can't just be set to zero at least at first?
Finally Z which is line checsksum - I don't easily
understand the definition "the sum of all integer
characters on a line plus a 1 for each negaitve sign -
it's the modulo-10 of the sume ofthedigits and
negative signs" (I might get there and will try when
I've done the rest).
Would appreciate it if amsatters who are better
mathematicians than I am, could conclude the TLE, then
I plan to use STS+ in time simulation mode to run it.
73 de andy G0SFJ
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