[amsat-bb] Tracking Non Earth Orbit Spacecraft......how?

Nico Janssen hamsat at xs4all.nl
Tue Oct 18 13:45:36 UTC 2016


Don't worry too much about frequent updates of ephemerides. Deep
space spacecraft don't experience as many perturbations as satellites
in low Earth orbit, like (variable) atmospheric drag.

If you really want to dive into serious orbit modeling and tracking,
also for deep space, you should have a look at the General Mission
Analysis Tool (GMAT):


On 18-10-16 00:24, Zach Leffke wrote:
> Thanks for the response Nico.  Pete, WA6WOA, also recommend I take a 
> look at the Horizons system as well.  I gave it a quick once over, and 
> actually logged into the telnet interface and played around a bit.  It 
> definitely looks like the type of thing I'm looking for.  Next step 
> for me is to learn the API and figure out how to integrate with my 
> existing Python tools.  Also, changing how I think about satellite 
> orbits and tracking algorithms is also probably a requirement for me 
> (I'm an EE type, not an AOE type, so probably time to learn a little 
> more about how these tracking algorithms actually work).
> Not being familiar with the system yet (or deep space tracking in 
> general), my only concern at the moment is the frequency with which 
> they update the system.  TLEs get updated pretty regularly and need to 
> be refreshed by the client software.  My cursory examination of the 
> HORIZONS system seems to indicate that they give ephemerides that 
> cover much longer windows, possibly indicating that they don't update 
> the data as frequently? Hopefully there is something about Deep Space 
> tracking that is different, not requiring such frequent updates.  I 
> have a sense that I'm not thinking about 'scale' correctly yet.  Like 
> maybe these objects are so far out, that errors that might creep into 
> the SGP4+TLE algorithms relatively quickly (requiring the weekly or 
> bi-weekly updates) take a lot longer to creep up and matter with the 
> deep space trajectories.
> My concern here is primarily related to the Cube Quest Challenge 
> stuff.  I think this is being launched as part of the Orion mission to 
> the Moon in the next couple years.  Can we expect ephemeris data to be 
> quickly added to the HORIZONS system soon after launch and after the 
> TLI burn for the Orion mission?  Maybe I'm just wrong about how 
> frequently they update the info.  Since this system is being run by 
> JPL, I'm assuming (maybe hoping?) that the datasets on HORIZONS get 
> updated every time they conduct ranging operations on active missions 
> with the DSN (kind of like TLEs get updated every time NORAD does 
> RADAR tracking for things closer in)?  Hopefully, this will then 
> include the Orion Mission relatively quickly so that the community can 
> quickly pull the tracking data required to compute pointing angles for 
> their ground stations to monitor the CQC bird.
> Thanks for the pointers folks.  In only a few emails, I've got some 
> great stuff to look into, and a whole new area to look into and learn 
> about!  Fun stuff!  Keep them coming!
> Thanks,
> Zach, KJ4QLP
> Research Associate
> Ted & Karyn Hume Center for National Security & Technology
> Virginia Polytechnic Institute & State University
> Work Phone: 540-231-4174
> Cell Phone: 540-808-6305

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