[amsat-bb] Re: Shuttle keps?

Joe Fitzgerald jfitzgerald at alum.wpi.edu
Thu Dec 21 08:53:00 PST 2006

MM wrote:

> The posted nasa keps are calculated before lanuch and
> do not seem to match very well. 

Not sure which site you are looking at, but NASA provides us with 
remarkably good data updated as the mission goes on at:


During last night's RAFT deployment party at AA2TX's place, we had some 
confusion over which element set to use.  We had our kids in the next 
room watching NASA TV, and they were asked to give us a yell when the 
Shuttle's cameras showed them crossing the coast of Australia.  When we 
heard the yell, InstantTrack's map, using an element set from the site 
above, showed the spacecraft not even one pixel away from the coast.

The same page shows the time (and if you are interested, the vector) of 
each orbital maneuver, as well as predicted keps before and after. For 
example there is a maneuver at 18:53 UTC today adding 2 feet per second 
in the direction of the orbit. I'm guessing that this maneuver is to get 
a little clearance from FCAL/ANDE scheduled to be deployed a half hour 

Before 18:53 21 DEC 06 UTC:

1 29647U 06055A   06354.96118119  .00014500  00000-0  95600-4 0  9004
2 29647  51.6315 304.5708 0017119   8.1770 351.9673 15.81496875  1739

After 18:53 21 DEC 06 UTC:
1 29647U 06055A   06355.84582753  .00014500  00000-0  95600-4 0  9012
2 29647  51.6335 299.9800 0018958  11.5381 348.6216 15.81158211  1879

Note that as the speed of the shuttle increases, the mean motion 
decreases and subsequent passes will be later than they would have been 
otherwise.  Get that relationship wrong and I know a certain guy from 
Annapolis who will make sure to set you straight! ;-)

-Joe KM1P

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